A catalyst and a method of preparing the same

Abstract

The present disclosure relates to a catalyst comprising: a compound of Formula (I), M Y --- (I), wherein M is a transition metal cation, the transition metal selected from the group consisting of cobalt (Co), iron (Fe), and nickel (Ni), copper (Cu), cerium (Ce), lanthanum (La), zinc (Zn), palladium (Pd), tungsten (W), molybdenum (Mo) and combinations thereof, and Y is an anion selected from phosphate (PO4 3-) or phosphide (P3-); and an activated carbon substrate, wherein the compound is disposed on the activated carbon substrate. The present disclosure also relates to a method of preparing said catalyst, the method comprising the steps of: a) mixing a salt of M with a phosphorus source in a solvent to form a precursor solution; b) applying the precursor solution on the activated carbon substrate; and c) heating the precursor solution and the activated carbon substrate for a period of about 0.25 ms to about 10 s to form said catalyst. The present disclosure further relates to a catalyst obtained or obtainable by the method as disclosed herein, and an electrode comprising the catalyst as disclosed herein.

Description

[0001] A CATALYST AND A METHOD OF PREPARING THE SAME

[0002] Cross-Reference to Related Applications

[0003] This application claims priority to Singapore application no. 10202402140X filed with the Intellectual Property Office of Singapore on 18 July 2024, the contents of which is hereby incorporated by reference in its entirety for all purposes.

[0004] Technical Field

[0005] The present disclosure generally relates to catalysts, and more particularly relates to electrocataly sts. The present disclosure also relates to methods of producing said catalysts and electrodes comprising said catalysts.

[0006] Background Art

[0007] Hydrogen, the lightest element, is a promising alternative energy storage and carrier agent due to its high gravimetric energy density of 120 MJ kg1at 298 K. Generating hydrogen from water is an environmentally conscious approach for energy usage and storage, mitigating climate change and supporting economic and technological developments. Tn water electrolysis, two simultaneous halfreactions occur: hydrogen evolution reaction (HER) and oxygen evolution reaction (OER). However, OER is more complex, requiring more reaction steps to transfer four electrons (compared to two for HER), and has sluggish kinetics and higher energy barriers for forming oxygcn-containing intermediates. Improving OER performance enhances the efficiency of water electrolysis and benefits clean energy applications, such as metal-air batteries and fuel cells. Typical benchmark OER catalysts include precious metal-based IrOz and RuOz that exhibit excellent catalytic performance . However, transition metal oxide catalysts, such as CoOx, NiOxand FeOx, are more stable in alkaline media as well as affordable. Other transition metal salts, such as nitrides, sulfides, phosphides, and phosphates, have shown outstanding electrocatalytic properties for OER, attributed to facilitating the formation of active metal oxides or hydroxides and enabling long term stability

[0008] Various strategies have been implemented to improve OER catalytic activities, including combining different metals and anion species, phase engineering, and exploiting synergistic effects with the catalyst support, such as enhanced electron and ion transport and improved wettability^ with the electrolyte. For example, mixing Fe with more electronegative Co and Ni lowers the oxygen binding energies, resulting in smaller reaction overpotential values, and facilitates the reconstruction into oxyhydroxides, increasing the number of electrocatalytically active sites and improving electronic conductivity.

[0009] It was previously demonstrated that substituting Fe into the otherwise inactive spinel COAI2O4 forms CoFeo.25Al175O4, a highly active and stable catalyst that expedited surface reconstruction into Co oxyhydroxides and stimulated a two-step deprotonation process at lower overpotentials, thereby augmenting oxygen generation. In another study, it was revealed that incorporating Fe into nickel oxyhydroxide altered the interactions between active oxygen species and OH groups, influencing the OER reaction pathway.

[0010] Transition metal phosphate (Pi) catalysts have been used for OER applications, and typically involve crystalline materials prepared through high-temperature processes such as hydrothermal and furnace annealing, which require extended periods, or through rapid thermal shocks occurring over short durations. For instance, a previous synthesis of multicomponent transition metal Pi particles was done using an aerosol fly-through process, wherein particles passed through a furnace held at 900 °C for subsecond timeframes. The resulting CoFcNiMnMoPi particles exhibited low overpotential and Tafcl slope values of 227 mV at 10 mA cm2and 74 mV dec '. respectively, showing better performance than commercial IrO: anode for OER. An oil-phase method was used to form ultrathin flakes of amorphous mesoporous NiCoPi, using a NiCo oleate precursor and tetradecylphosphonic acid as the P source, heated at 300 °C for about 1.5 hours under inert argon. Although the amorphous mesoporous NiCoPi catalyst exhibited a decent overpotential of 327 mV at 10 mA cm2and Tafel slope of 73.7 mV dec for OER, the multistep synthesis approach is tedious, and the NiCo oleate precursor must be prepared separately.

[0011] In addition, phosphides have also attracted significant attention due to their efficient and remarkable catalytic activity (HER and OER). Typical synthesis methods for phosphides includes solvothermal method, gas-solid reaction, thermal decomposition, clcctrodcposition, and laser annealing. For example, a vanadium -doped CoOOH on carbon cloth was obtained through hydrothermal synthesis and subsequently converted to V-C0P2 after phosphorization. The obtained V-C0P2 exhibits remarkable acidic overall water splitting activity, achieving 1.47 V at 10 mA cm-2.

[0012] However, it is challenging for current methods to control the crystal structure and stoichiometric ratio of metal to phosphorus. Based on the ratios of metal / phosphorus (M:P), metal phosphides are categorized into metal-rich phosphides (M:P > 1 , e g., M2P. M3P), monophosphides (M:P = 1), and phosphorus-rich metal phosphides (NEP < 1, e g., MP2, MP3). Phosphorus-rich metal phosphides normally exhibit worse electrical conductivity' compared to metal-rich metal phosphides because the P atoms with strong electronegativity’ can limit electron delocalization in metal sites.

[0013] Thus, there is a need to provide a catalyst that overcomes, or at least ameliorates one or more of the disadvantages described above.

[0014] Summary

[0015] Tn an aspect of the present disclosure, there is provided a catalyst comprising: a compound of Formula (I),

[0016] M Y — (I), wherein:

[0017] M is a transition metal cation, the transition metal selected from the group consisting of cobalt (Co), iron (Fe), and nickel (Ni), copper (Cu), cerium (Ce), lanthanum (La), zinc (Zn). palladium (Pd), tungsten (W), molybdenum (Mo) and combinations thereof, and

[0018] Y is an anion selected from phosphate (PO? ) or phosphide (P3); and an activated carbon substrate, wherein the compound is disposed on the activated carbon substrate.

[0019] Advantageously, the catalyst may’ exhibit more active sites as compared to conventional catalysts, as well as superior electron transport. Further advantageously, the presence of the activated carbon substrate may aid in enhancing the wetting properties (when used as an electrode in an electrochemical cell) with the electrolyte, which may result in enhanced mass transport of charged ionic species during electrocatalysis. In another aspect of the present disclosure, there is provided a method of preparing a catalyst comprising: a compound of Formula (1),

[0020] M Y — (I), wherein:

[0021] M is a transition metal cation, the transition metal selected from the group consisting of cobalt (Co), iron (Fe), nickel (Ni), copper (Cu), cerium (Ce), lanthanum (La), zinc (Zn), palladium (Pd), tungsten (W), molybdenum (Mo) and combinations thereof, and

[0022] Y is an anion selected from phosphate (PO ) and or phosphide (P3); and an activated carbon substrate, wherein the compound is disposed on the activated carbon substrate, the method comprising the steps of: a) mixing a salt of M with a phosphorus source in a solvent to form a precursor solution; b) applying the precursor solution on the activated carbon substrate; and c) heating the precursor solution and the activated carbon substrate for a period of about 0.25 ms to about 10 s to form said catalyst.

[0023] Advantageously , the method as disclosed herein may be performed quickly, and may be completed within seconds. Further advantageously, the disclosed method may readily give access to catalysts with different amorphous or crystalline structures, as well as be readily adapted to utilize different transition metal salts. The method may also advantageously utilize cheap, non-toxic, and widely available starting materials. Heating the precursor solution together with the activated carbon substrate may advantageously result in hcat-induccd bonding of the compound to the activated carbon substrate, which may minimize electrical contact resistance between the compound and activated carbon substrate via intimate contact. This may also advantageously result in the compound being coated thinly and homogeneously on the activated carbon substrate, which may allow the catalyst to exhibit an increased number of active sites, and superior electron transport.

[0024] In a further aspect of the present disclosure, there is provided a catalyst obtained or obtainable by the method as disclosed herein.

[0025] In another aspect of the present disclosure, there is provided an electrode comprising the catalyst as disclosed herein.

[0026] Advantageously, the catalyst may exhibit excellent perfomiance as an OER electrode, with an overpotential as low as 235 mV to drive a current density of 10 mA cm-2, a Tafel slope as low as 32.2 mV dec1, rapid OER surface kinetics, charge transfer resistance values as low as 0.22 Q. and overpotential remaining robust at 250 mV even after 100 hours of chronopotentiometry at the current density' of 10 mA cm .

[0027] Definitions

[0028] Unless otherwise defined herein, scientific and technical terms used in this application shall have the meanings that arc commonly understood by those of ordinary skill in the art. Generally, nomenclature used in connection with, and techniques of, chemistry described herein, are those well-known and commonly used in the art. Unless the context requires otherwise or specifically stated to the contrary, integers, steps, or elements of the invention recited herein as singular integers, steps or elements clearly encompass both singular and plural forms of the recited integers, steps or elements.

[0029] The word “substantially” does not exclude “completely” e.g. a composition which is “substantially free” from Y may be completely free from Y. Where necessary, the word “substantially” may be omitted from the definition of the invention.

[0030] As used herein, the term "amorphous" refers to a solid form of a molecule, atom, and / or ions that is not crystalline.

[0031] As used herein, the term “hierarchically porous”, or also sometimes referred to using the acronym “HP”, refers to the presence of at least two different pore sizes, wherein the pores arc macroporcs, mesopores, or micropores. Macropores are generally known as, and in accordance with the IUPAC nomenclature, pores with a diameter of greater than 50 nm, mesopores as pores having a diameter of greater than 2 nm and up to 50 nm, and micropores as pores with a diameter of up to 2 nm. The pore size distribution can be measured by methods known to a person skilled in the art, such as the Barrett-Joyner- Halenda (BJH) method.

[0032] As used herein, the term “superhydrophilic” refers to an attribute of a substrate whereby the contact angle between a water droplet (when placed on a surface of the substrate) and the surface of the substrate is smaller than about 10°.

[0033] As used herein, the term “homogeneous” refers to a compound having uniform composition throughout its entire chemical structure. When used in reference to a coating on a substrate, it refers to the coating having a uniform composition.

[0034] As used herein in the specification and in the claims, the phrase "at least," in reference to a list of one or more elements, should be understood to mean at least one element selected from any one or more of the elements in the list of elements, but not necessarily including at least one of each and every element specifically listed within the list of elements and not excluding any combinations of elements in the list of elements. This definition also allows that elements may optionally be present other than the elements specifically identified within the list of elements to which the phrase "at least one" refers, whether related or unrelated to those elements specifically identified. Thus, as a non-limiting example, "at least one of A and B" (or, equivalently, "at least one of A or B," or, equivalently "at least one of A and / or B") can refer, in one embodiment, to at least one, optionally including more than one, A, with no B present (and optionally including elements other than B); in another embodiment, to at least one, optionally including more than one, B, with no A present (and optionally including elements other than A); in yet another embodiment, to at least one, optionally including more than one, A, and at least one, optionally including more than one, B (and optionally including other elements); etc.

[0035] Unless specified otherwise, the terms "comprising" and "comprise", and grammatical variants thereof, are intended to represent "open" or "inclusive" language such that they include recited elements but also permit inclusion of additional, unrccitcd elements.

[0036] As used herein, the term "about", in the context of concentrations of components of the formulations, typically means + / - 5% of the stated value, more typically + / - 4% of the stated value, more typically + / - 3% of the stated value, more typically, + / - 2% of the stated value, even more typically + / - 1% of the stated value, and even more typically + / - 0.5% of the stated value. Throughout this disclosure, certain embodiments may be disclosed in a range format. It should be understood that the description in range format is merely for convenience and brevity and should not be construed as an inflexible limitation on the scope of the disclosed ranges. Accordingly, the description of a range should be considered to have specifically disclosed all the possible sub-ranges as well as individual numerical values within that range. For example, description of a range such as from 1 to 6 should be considered to have specifically disclosed sub-ranges such as from 1 to 3, from 1 to 4, from 1 to 5, from 2 to 4, from 2 to 6, from 3 to 6 etc., as well as individual numbers within that range, for example, 1, 2, 3, 4, 5, and 6. This applies regardless of the breadth of the range.

[0037] Certain embodiments may also be described broadly and generically herein. Each of the narrower species and subgeneric groupings falling within the generic disclosure also form part of the disclosure. This includes the generic description of the embodiments with a proviso or negative limitation removing any subject matter from the genus, regardless of whether or not the excised material is specifically recited herein.

[0038] Brief Description of Drawings

[0039] The accompanying drawings illustrate disclosed embodiments and serve to explain the principles of the disclosed embodiments. It is to be understood, however, that the drawings are designed for purposes of illustration only, and not as a definition of the limits of the invention.

[0040] Fig. l

[0041] Fig. 1 is an empirical plot of infrared temperature versus heating time during Joule heating set at 22 V and 20 A.

[0042] Fig. 2a

[0043] Fig. 2a is a schematic representation of a method to form a catalyst according to an embodiment via Joule heating.

[0044] Fig. 2b

[0045] Fig. 2b is a scanning electron microscopy (SEM) micrograph of an embodiment of the present invention (CoFcNiPi@ACC), at 1 pm scale. The inset is of the same embodiment but at 100 nm scale.

[0046] Fig. 2c

[0047] Fig. 2c is a high resolution-transition electron microscopy micrograph of the embodiment of Fig. 2b at 5 nm scale. The inset is a selected area electron diffraction (SAED) micrograph of the same embodiment at 5 1 / nm scale.

[0048] Fig. 2d

[0049] Fig. 2d is a series of wide-angle x-ray scattering (WAXS) spectra of a comparative embodiment (uncoated activated carbon cloth (ACC)) and embodiments of the present invention (CoPi@:ACC, CoFePi@ACC and CoFeNiPi@ACC).

[0050] Fig. 2e

[0051] Fig. 2e is a high-angle annular dark-field scanning transmission electron microscopy (HAADF-STEM) image of an embodiment of the present invention (CoFeNiPi@ACC) and its corresponding energy dispersive spectroscopy (EDS) maps of said embodiment after Joule heating. Fig. 3a

[0052] Fig. 3a is an image showing the water contact angle measurement of a comparative embodiment (carbon cloth) before contact.

[0053] Fig. 3b

[0054] Fig. 3b is an image showing the water contact angle measurement of a comparative embodiment (carbon cloth) after contact.

[0055] Fig. 3c

[0056] Fig. 3c is an image showing the water contact angle measurement of an embodiment of the present invention (heat-treated and KOH-activated carbon cloth) before contact.

[0057] Fig. 3d

[0058] Fig. 3d is an image showing the water contact angle measurement of an embodiment of the present invention (heat-treated and KOH-activated carbon cloth) after contact.

[0059] Fig. 4

[0060] Fig. 4 is a bar chart showing the measurements of a comparative embodiment (individual uncoated ACC fibers) and an embodiment of the present invention (CoFeNiPi@ACC fibers) after Joule heating.

[0061] Fig. 5a

[0062] Fig. 5a is a SEM micrograph showing the relatively smooth surface of an embodiment of the present invention (CoPi@ACC) after Joule heating for 100 ms at -420 °C at 1 pm scale.

[0063] Fig. 5b

[0064] Fig. 5b is a SEM micrograph showing the relatively smooth surface of an embodiment of the present invention (CoPi@ACC) after Joule heating for 100 ms at ~420 °C at 100 nm scale.

[0065] Fig. 5c

[0066] Fig. 5c is a SEM micrograph showing the relatively smooth surface of an embodiment of the present invention (CoFePi@ACC) after Joule heating for 100 ms at -420 °C at 1 pm scale.

[0067] Fig. 5d

[0068] Fig. 5d is a SEM micrograph showing the relatively smooth surface of an embodiment of the present invention (CoFePi@ACC) after Joule heating for 100 ms at -420 °C at 100 nm scale.

[0069] Fig. 6a

[0070] Fig. 6a is a series of Co 2p XPS spectra of an embodiment of the present invention (CoFeNiPi@ACC) as- made and after 24 hours of chronopotentiometry.

[0071] Fig. 6b

[0072] Fig. 6b is a series of Fe 2p XPS spectra of an embodiment of the present invention (CoFeNiPi@ACC) as-made and after 24 hours of chronopotentiometry.

[0073] Fig. 6c

[0074] Fig. 6c is a series of Ni 2p XPS spectra of an embodiment of the present invention (CoFeNiPi@ACC) as- made and after 24 hours of chronopotentiometry. Fig. 6d

[0075] Fig. 6d is a senes of O Is XPS spectra of an embodiment of the present invention (CoFeNiPi@ACC) as- made and after 24 hours of chronopotcntiomctry.

[0076] Fig. 6e

[0077] Fig. 6e is a series of P 2p XPS spectra of an embodiment of the present invention (CoFeNiPi@ACC) as- made and after 24 hours of chronopotentiometry.

[0078] Fig. 6f

[0079] Fig. 6f is a series of C Is XPS spectra of an embodiment of the present invention (CoFeNiPi@ACC) as- made and after 24 hours of chronopotentiometry.

[0080] Fig. 7a

[0081] Fig. 7a is a series of iR-corrected OER polarization curves of amorphous samples of embodiments of the present invention (CoFeNiPi@ACC, CoFePi@ACC, CoPi@ACC) and comparative embodiments (RUO2@ACC, and uncoated ACC) in 1.0 M KOH.

[0082] Fig. 7b

[0083] Fig. 7b is a series of bar charts showing the overpotential of embodiments of the present invention (CoFeNiPi@ACC, CoFePi@ACC, CoPi@ACC) at current densities of 10, 50, and 100 mA cm \

[0084] Fig. 7c

[0085] Fig. 7c is a scries of Tafel plots of embodiments of the present invention (CoFcNiPi@ACC, CoFePi@ACC, CoPi@ACC) and a comparative embodiment (RuO2@ACC).

[0086] Fig. 7d

[0087] Fig. 7d is a series of Nyquist plots of embodiments of the present invention (CoFeNiPi@ACC, CoFcPi@ACC, CoPi@ACC) and a comparative embodiment (RuO2@ACC). Inset is the equivalent resistance circuit.

[0088] Fig. 7e

[0089] Fig. 7e is a series of plots of Cai values (Aj / 2 versus CV scan rate) of embodiments of the present invention (CoFcNiPi@ACC, CoFcPi@ACC, CoPi@ACC) and a comparative embodiment (RuO2@ACC).

[0090] Fig. 7f

[0091] Fig. 7f is a plot of overpotential required to drive 10 mA cm2against Tafel slope for an embodiment of the present invention (CoFeNiPi@ACC) and various comparative embodiments (TiO2|Co2P4Oi2, NiCoPi, CoNiPi@V-Co4N, NiCoFeMnMoPi, V-FePz / FePCX, NiFePi, Nii.5Sn@triMPO4, Co2(OH)2(HPO4)2 / NF, and Coi.6Nio.4P40i2-C).

[0092] Fig. 7g

[0093] Fig. 7g is a chronopotcntiomctry curve of an embodiment of the present invention (CoFeNiPi@ACC) over 100 hours at a constant current density of 10 mA cm2.

[0094] Fig. 8a

[0095] Fig. 8a is a series of polarization curves of various embodiments of the present invention (CoFeNiPi@ACC, FePi@ACC, CoPi@ACC, and NiPi@ACC). Fig. 8b

[0096] Fig. 8b is a series of polarization curves of various embodiments of the present invention (CoFcNiPi@ACC, CoFcPi@ACC, CoNiPi@ACC, and FcNiPi@ACC).

[0097] Fig. 9

[0098] Fig. 9 is a spectrum showing the WAXS patterns of an embodiment of the present invention (CoFeNi- P@ACC) Joule heated for 250 ms and 500 ms.

[0099] Fig. 10a

[0100] Fig. 10a is a series of polarization curves of various embodiments of the present invention (CoFeNiPi@ACC, CoFeNi-P@ACC-250, and CoFeNi-P@ACC-500).

[0101] Fig. 10b

[0102] Fig. 10b is a series of Tafel slopes of various embodiments of the present invention (CoFeNiPi@ACC, CoFeNi-P@ACC-250, and CoFeNi-P@ACC-500).

[0103] Fig. Ila

[0104] Fig. I la is a series of cyclic voltammetry (CV) plots of an embodiment of the present invention (CoPi@ACC) measured between 1.05 to 1.15 V at various scan rates from 20 to 120 mV s’1.

[0105] Fig. 11b

[0106] Fig. 11b is a series of cyclic voltammetry (CV) plots of an embodiment of the present invention (CoFcPi@ACC) measured between 1.05 to 1.15 V at various scan rates from 20 to 120 mV s’1.

[0107] Fig. 11 c

[0108] Fig. 11c is a series of cyclic voltammetry (CV) plots of an embodiment of the present invention (CoFeNiPi@ACC) measured between 1.05 to 1.15 V at various scan rates from 20 to 120 mV s’1.

[0109] Fig. 12

[0110] Fig. 12 is a series of polarization curves of various embodiments of the present invention (CoFeNiPi@ACC, CoFePi@ACC, CoPi@ACC) as a function of electrochemical surface area (ECSA)

[0111] Fig. 13

[0112] Fig. 13 is a series of polarization curves of an embodiment of the present invention (CoFeNiPi@ACC) and precursors to said embodiment coated on ACC (Precursor@ACC), activated and after immersion in 1 M KOH for 3 hours.

[0113] Fig. 14

[0114] Fig. 14 is a chronopotentiometry’ curve for a precursor to an embodiment of the present invention (Precursor@ACC) over 6 hours at a constant current density of 10 mA cm2.

[0115] Fig. 15a

[0116] Fig. 15a is a senes of CV plots showing the pseudocapacitive behaviors in the first and second CV cycles of various embodiments of the present invention (CoPi@ACC, CoFcPi@ACC, CoNiPi@ACC and CoFeNiPi@ACC) at a scan rate of 10 mV s1.

[0117] Fig. 15b

[0118] Fig. 15b is a series of Raman spectra of an embodiment of the present invention (CoFeNiPi@ACC) as- made, upon activation, and after chronopotentiometry for 24 hours and 100 hours. Fig. 15c

[0119] Fig. 15c is a series of figures showing the EDS line scan analysis of an embodiment of the present invention (CoFeNiPi@ACC) after chronopotentiometry for 24 hours.

[0120] Fig. 16

[0121] Fig. 16 is a series of Raman spectra of various embodiments of the present invention (CoPi@ACC, CoFePi@ACC) in the activated state.

[0122] Fig. 17a

[0123] Fig. 17a is an EDS line scan analysis of an embodiment of the present invention (CoFeNiPi@ACC) in the as-made state after Joule heating.

[0124] Fig. 17b

[0125] Fig. 17b is an EDS line scan analysis of an embodiment of the present invention (CoFeNiPi@ACC) after chronopotentiometry at a constant current density of 10 mA / cm2for 100 hours.

[0126] Fig. 18

[0127] Fig. 18 is a series of WAXS spectra of an embodiment of the present invention (CoFeNiPi@ACC) after chronopotentiometry' at a constant current density of 10 mA cm ’ over 24 hours and 100 hours.

[0128] Fig. 19a

[0129] Fig. 19a is an SEM image of an embodiment of the present invention (CoFcPi@ACC) after chronopotentiometiy' at a constant current density of 10 mA cm2for 24 hours at 1 pm scale.

[0130] Fig. 19b

[0131] Fig. 19b is an SEM image of an embodiment of the present invention (CoFcPiri ACC) after chronopotcntiomctry at a constant current density of 10 mA cm2for 24 hours at 100 nm scale.

[0132] Fig. 19c

[0133] Fig. 19c is an SEM image of an embodiment of the present invention (CoFePi@ACC) after chronopotentiometiy' at a constant current density of 10 mA cm2for 100 hours at 1 pm scale.

[0134] Fig. 19d

[0135] Fig. 19d is an SEM image of an embodiment of the present invention (CoFePi@:ACC) after chronopotentiometi ' at a constant current density of 10 mA cm2for 100 hours at 100 nm scale.

[0136] Fig. 20a

[0137] Fig. 20a is a Co 2p XPS spectra of an embodiment of the present invention (CoFeNiPi@ACC) after 100 hours of chronopotentiometry.

[0138] Fig. 20b

[0139] Fig. 20b is a Fe 2p XPS spectra of an embodiment of the present invention (CoFeNiPi@:ACC) after 100 hours of chronopotcntiomctry.

[0140] Fig. 20c

[0141] Fig. 20c is a Ni 2p XPS spectra of an embodiment of the present invention (CoFeNiPi@ACC) after 100 hours of chronopotentiometry. Fig. 20d

[0142] Fig. 20d is an 0 Is XPS spectra of an embodiment of the present invention (CoFeNiPi@ACC) after 100 hours of chronopotcntiomctry.

[0143] Fig. 20e

[0144] Fig. 20e is a P 2p XPS spectra of an embodiment of the present invention (CoFeNiPi@ACC) after 100 hours of chronopotentiometry.

[0145] Fig. 21a

[0146] Fig. 21a is a series of polarization curves of an embodiment of the present invention (CoFeNiPi@ACC) in TMAOH and KOH.

[0147] Fig. 21b

[0148] Fig. 21b is a series of Tafel slopes of an embodiment of the present invention (CoFeNiPi@ACC) in

[0149] TMAOH and KOH

[0150] Fig. 22a

[0151] Fig. 22a is an SEM image of an embodiment of the present invention (CoFeNiP@ACC) formed after Joule heating for 0.25 seconds, magnification at xl0,000.

[0152] Fig. 22b

[0153] Fig. 22b is an SEM image of an embodiment of the present invention (CoFeNiP@ACC) formed after Joule heating for 0.5 seconds, magnification at xl0,000.

[0154] Fig. 22c

[0155] Fig. 22c is an SEM image of an embodiment of the present invention (CoFeNiP@ACC) formed after Joule heating for 2.5 seconds, magnification at xl0,000.

[0156] Fig. 22d

[0157] Fig. 22d is a series of WAXS spectra of an embodiment of the present invention (CoFeNiP@ACC) formed after Joule heating for 0.25, 0.5, and 2.5 seconds.

[0158] Fig. 23

[0159] Fig. 23 is a series of iR-corrected OER polarization curves for an embodiment of the present invention (CoFeNiP@ACC) in the crystalline fonn after Joule heating for 0.25, 0.5, and 2.5 seconds.

[0160] Fig. 24a

[0161] Fig. 24a is an SEM image with a scale bar of 100 nm of an embodiment of the present invention (CoCuFeNiPdP) obtained by laser annealing at 4 W and 2.5 ms dwell time.

[0162] Fig. 24b

[0163] Fig. 24b is an SEM image with a scale bar of 100 nm of an embodiment of the present invention (CoCuFeNiPdP) obtained by laser annealing at 4 W and 5 ms dwell time.

[0164] Fig. 24c

[0165] Fig. 24c is an SEM image with a scale bar of 100 nm of an embodiment of the present invention (CoCuFeNiPdP) obtained by laser annealing at 4 W and 10 ms dwell time. Fig. 24d

[0166] Fig. 24d is an SEM image with a scale bar of 1000 nm of an embodiment of the present invention (CoCuFeNiPdP) obtained by laser annealing at 4 W and 15 ms dwell time.

[0167] Fig. 24e

[0168] Fig. 24e is an SEM image with a scale bar of 100 nm of an embodiment of the present invention (CoCuFeNiPdP) obtained by laser annealing at 6 W and 2.5 ms dwell time.

[0169] Fig. 24f

[0170] Fig. 24f is an SEM image with a scale bar of 100 nm of an embodiment of the present invention (CoCuFeNiPdP) obtained by laser annealing at 6 W and 5 ms dwell time.

[0171] Fig. 24g

[0172] Fig. 24g is a series of WAXS spectra of an embodiment of the present invention (CoCuFeNiPdP) obtained by laser annealing at powers ranging from 2 to 6 W and dwell times from 2.5 to 15 ms.

[0173] Fig. 25a

[0174] Fig. 25a is a series of WAXS spectra of an embodiment of the present invention (CoCuFeNiWP@ACC- 100ms) and (CoCuFeNiW-P@ACC-500ms) formed after Joule heating for 0.1 and 0.5 seconds.

[0175] Fig. 25b

[0176] Fig. 25b is a series of iR-corrected OER polarization curves for an embodiment of the present invention (CoCuFcNiWP@:ACC-100ms) and (CoCuFcNiW-P@ACC-500ms) formed after Joule heating for 0.1 and 0.5 seconds.

[0177] Fig. 25c

[0178] Fig. 25c is a series of Tafel plot for an embodiment of the present invention (CoCuFeNiWP@ACC-100ms) and (CoCuFcNiW-P@ACC-500ms) formed after Joule heating for 0.1 and 0.5 seconds.

[0179] Detailed Disclosure of Optional Embodiments

[0180] Provided herein is a catalyst comprising: a compound of Formula (I),

[0181] M Y — (I), wherein:

[0182] M is a transition metal cation, the transition metal selected from the group consisting of cobalt (Co), iron (Fe), and nickel (Ni), copper (Cu), cerium (Ce), lanthanum (La), zinc (Zn), palladium (Pd), tungsten (W), molybdenum (Mo) and combinations thereof, and

[0183] Y is an anion selected from phosphate (PO43) or phosphide (P3): and an activated carbon substrate, wherein the compound is disposed on the activated carbon substrate.

[0184] Advantageously, the catalyst may exhibit excellent performance as an OER electrode, with a low overpotential, a small Tafel slope, rapid OER surface kinetics, low charge transfer resistance values and high stability. The inventors have surprisingly found that this may be due to the direct formation of an amorphous metal phosphate structure, the pre-oxidation of transition metal cation precursors to higher oxidation states, fast charge transfer kinetics, and the facilitation of metal oxyhydroxide species formation through self-reconstruction during the OER.

[0185] The inventors have also surprisingly found that the phosphate group (Pi), a bulky, oppositely charged entity with nucleophilic properties, may act as an effective proton acceptor, which may advantageously facilitate key proton transfer steps in OER, influence water adsorption dynamics and stabilize reaction intermediates such as HOO* by modifying the electronic and geometric properties of the metal adsorption site. The inventors have further surprisingly found that Pi may enhance chemical stability, increase the metal oxidation state, advantageously leading to enhanced electron transfer kinetics, boost the total number active sites, and facilitate the reconstruction process into oxyhydroxides. Tire inventors have also surprisingly found that the presence of phosphorus vacancies may also increase the number of long- pair electrons, which may advantageously result in enhanced electrical conductivity. In addition, phosphorus vacancies provide abundant active sites, which may enhance to the catalytic performance. Further, the intrinsic structural disorder may enhance ion diffusion and facilitate self-reconstruction into an amorphous oxyhydroxide structure.

[0186] The inventors have surprisingly found that the presence of an activated carbon substrate may enhance wetting properties with the electrolyte (when the catalyst is formed into an electrode in an electrochemical cell), which may result in enhanced mass transport of charged ionic species during electrocatalysis.

[0187] The atomic ratio of M to Y may be in a range of about 1 : 0.5 to about 1:5, from about 1 : 0.5 to about 1:4.5, from about 1:0.5 to about 1:4, from about 1:0.5 to about 1:3.5, from about 1:0.5 to about 1:3.1, from about 1:0.5 to about 1:3, from about 1:0.5 to about 1:2.5, from about 1:0.5 to about 1:2, from about 1:0.5 to about 1 : 1.5, from about 1 :0.5 to about 1 : 1 , or from about 1 : 1 to about 1 :5, from about 1 : 1 .5 to about 1 :5, from about 1:2 to about 1:5, from about 1:2.5 to about 1:5, from about 1:3 to about 1:5, from about 1:3.1 to about 1:5, from about 1:3.5 to about 1:5, from about 1:4 to about 1:5, from about 1:4.5 to about 1:5, or about 1:0.5, about 1: 1, about 1: 1.5, about 1:2, about 1:2.5, about 1:3, about 1:3.1, about 1:3.5, about 1:4.0, about 1:4.5, about 1:5.0, or any value or range therein. It is to be appreciated that the above ranges should be interpreted as including and supporting any sub-ranges or discrete values (which may or may not be a whole number) that are within the stated range(s).

[0188] M may be a combination of transition metal cations as shown in Formula (II),

[0189] [M1M2M3M4M5ln-—(II).

[0190] In some embodiments, M1, M2, M3, M4or M5may each individually be present at an atomic ratio in a range of about 0.05 to about 0.95, from about 0.05 to about 0.90, from about 0.05 to about 0.85, from about 0.05 to about 0.80, from about 0.05 to about 0.75, from about 0.05 to about 0.70, from about 0.05 to about 0.65, from about 0.05 to about 0.61, from about 0.05 to about 0.60, from about 0.05 to about 0.55, from about 0.05 to about 0.50, from about 0.05 to about 0.45, from about 0.05 to about 0.43, from about 0.05 to about 0.40, from about 0.05 to about 0.39, from about 0.05 to about 0.35, from about 0.05 to about 0.34, from about 0.05 to about 0.30, from about 0.05 to about 0.25, from about 0.05 to about 0.22, from about 0.05 to about 0.20, from about 0.05 to about 0.15, from about 0.05 to about 0.10, or from about 0.10 to about 0.95, from about 0.15 to about 0.95, from about 0.20 to about 0.95, from about 0.22 to about 0.95, from about 0.25 to about 0.95, from about 0.30 to about 0.95, from about 0.34 to about 0.95, from about 0.35 to about 0.95, from about 0.39 to about 0.95, from about 0.40 to about 0.95, from about 0.43 to about 0.95, from about 0.45 to about 0.95, from about 0.50 to about 0.95, from about 0.55 to about 0.95, from about 0.60 to about 0.95, from about 0.61 to about 0.95, from about 0.65 to about 0.95, from about 0.70 to about 0.95, from about 0.75 to about 0.95, from about 0.80 to about 0.95, from about 0.85 to about 0.95, from about 0.90 to about 0.95, or about 0.05, about 0.10, about 0.15, about 0.20, about 0.22, about 0.25, about 0.30, about 0.34, about 0.35, about 0.39, about 0.40, about 0.43, about 0.45, about 0.50, about 0.55, about 0.60, about 0.61, about 0.65, about 0.70, about 0.75, about 0.80, about 0.85, about 0.90, about 0.95.

[0191] It is to be appreciated that the above ranges should be interpreted as including and supporting any subranges or discrete values (which may or may not be a whole number) that are within the stated range(s).

[0192] Alternatively, M3, M4or M5may each individually be absent.

[0193] In some embodiments, M may be selected from the group consisting of Co, CoFe, CoFeNi, CoCuFeNiPd , CoCuFeNiMo, and CoCuFeNiW.

[0194] The compound may be amorphous. The compound may be crystalline. Advantageously, an amorphous compound may exhibit enhanced OER performance due to the intrinsic activity improvement of amorphous compounds. The inventors have surprisingly found that this may be due to more active sites being found in an amorphous compound as compared to a crystalline compound Further advantageously, an amorphous compound may be able to be reconstructed into an oxyhydroxide more quickly than a crystalline compound.

[0195] The compound may be disposed on the activated carbon substrate in the form of a film. Advantageously, the compound being in the form of a film may allow it to form a homogeneous layer on the activated carbon substrate, thus facilitating electron transport and exhibiting superior OER properties. The film may have a thickness in a range of about 50 nm to about 1000 nm, from about 50 nm to about 950 nm, from about 50 nm to about 900 nm, from about 50 nm to about 850 nm, from about 50 nm to about 800 nm, from about 50 nm to about 750 nm, from about 50 nm to about 700 nm, from about 50 nm to about 650 nm, from about 50 nm to about 600 nm, from about 50 nm to about 550 nm, from about 50 nm to about 500 nm, from about 50 nm to about 450 nm, from about 50 nm to about 400 nm, from about 50 nm to about 350 nm, from about 50 nm to about 300 nm, from about 50 nm to about 250 nm, from about 50 nm to about 200 nm, from about 50 nm to about 165 nm, from about 50 nm to about 150 nm, from about 50 nm to about 100 nm, or from about 100 nm to about 1000 nm, from about 150 nm to about 1000 nm, from about 165 nm to about 1000 nm, from about 200 nm to about 1000 nm, from about 250 nm to about 1000 nm, from about 300 nm to about 1000 nm, from about 350 nm to about 1000 nm, from about 400 nm to about 1000 nm, from about 450 nm to about 1000 nm, from about 500 nm to about 1000 nm, from about 550 nm to about 1000 nm, from about 600 nm to about 1000 nm, from about 650 nm to about 1000 nm, from about 700 nm to about 1000 nm, from about 750 nm to about 1000 nm, from about 800 nm to about 1000 nm, from about 850 nm to about 1000 nm, from about 900 nm to about 1000 nm, from about 950 nm to about 1000 nm, or about 50 nm, about 100 nm, about 150 nm, about 165 nm, about 200 nm, about 250 nm, about 300 nm, about 350 nm, about 400 nm, about 450 nm, about 500 nm, about

[0196] 550 nm, about 600 nm, about 650 nm, about 700 nm, about 750 nm, about 800 nm, about 850 nm, about 900 nm, about 950 nm, about 1000 nm, or any value or range therein. It is to be appreciated that the above ranges should be interpreted as including and supporting any sub-ranges or discrete values (which may or may not be a whole number) that are within the stated range(s).

[0197] The compound may be disposed on the activated carbon substrate as particles. The particles may each independently have a particle size in a range of about 0.01 pm to about 10.0 pm, from about 0.01 pm to about 9.5 pm, from about 0.01 pm to about 9.0 pm, from about 0.01 pm to about 8.5 pm, from about 0.01 pm to about 8.0 pm, from about 0.01 pm to about 7.5 pm, from about 0.01 pm to about 7.0 pm, from about 0.01 pm to about 6.5 pm, from about 0.01 pm to about 6.0 pm, from about 0.01 pm to about 5.5 pm, from about 0.01 pm to about 5.0 pm, from about 0.01 pm to about 4.5 pm, from about 0.01 pm to about 4.0 pm, from about 0.01 pm to about 3.5 pm, from about 0.01 pm to about 3.0 pm, from about 0.01 pm to about 2.5 pm, from about 0.01 pm to about 2.0 pm, from about 0.01 pm to about 1.5 pm, from about 0.01 pm to about 1.0 pm. from about 0.01 pm to about 0.5 pm, from about 0.01 pm to about 0.1 pm, from about 0.01 pm to about 0.05 pm, or from about 0.05 pm to about 10.0 pm, from about 0.1 pm to about 10.0 pm, from about 0.5 pm to about 10.0 pm, from about 1.0 pm to about 10.0 pm, from about 1.5 pm to about 10.0 pm, from about 2.0 pm to about 10.0 pm, from about 2.5 pm to about 10.0 pm, from about 3.0 pm to about 10.0 pm, from about 3.5 pm to about 10.0 pm, from about 4.0 pm to about 10.0 pm, from about 4.5 pm to about 10.0 pm, from about 5.0 pm to about 10.0 pm, from about 5.5 pm to about 10.0 pm, from about 6.0 pm to about 10.0 pm, from about 6.5 pm to about 10.0 pm, from about 7.0 pm to about 10.0 pm. from about 7.5 pm to about 10.0 pm, from about 8.0 pm to about 10.0 pm, from about 8.5 pm to about 10.0 pm, from about 9.0 pm to about 10.0 pm, from about 9.5 pm to about 10.0 pm, or about 0.01 pm, about 0.05 pm, about 0.1 pm, about 0.5 pm, about 1.0 pm, about 1.5 pm, about 2.0 pm, about 2.5 pm, about 3.0 pm, about 3.5 pm, about 4.0 pm, about 4.5 pm, about 5.0 pm, about 5.5 pm, about 6.0 pm, about 6.5 pm, about 7.0 pm, about 7.5 pm, about 8.0 pm, about 8.5 pm, about 9.0 pm, about 9.5 pm, about 10.0 pm, or any value or range therein. It is to be appreciated that the above ranges should be interpreted as including and supporting any sub-ranges or discrete values (which may or may not be a whole number) that are within the stated range(s).

[0198] The compound disposed on the activated carbon substrate may be bonded to the activated carbon substrate via heat-induced bonding as compared to the compound being physically adhered or coated onto the activated carbon substrate as a discrete layer or coating after the compound is formed. Advantageously, the compound being bonded to the activated carbon substrate via heat-induced bonding may minimise electrical contact resistance via intimate contact with each other, thus leading to advantageous OER properties. The improved contact lowers resistance for electrons to transfer from active catalyst to carbon scaffold for the electrical circuit.

[0199] The compound may be disposed on the activated carbon substrate homogeneously. Advantageously, a homogeneous coating of the compound on the activated carbon substrate may facilitate electron transport within the compound, thus leading to better OER performance.

[0200] The activated carbon substrate may be hydrophilic. The activated carbon substrate may be superhydrophilic. The activated carbon substrate may be highly porous. Advantageously, a superhydrophilic and / or highly porous activated carbon substrate may facilitate mass transport during OER. The inventors have surprisingly found that this is due to the fast elimination of generated bubbles under high current densities, which prevents charged ionic species from being blocked from the active catalytic sites.

[0201] The activated carbon substrate may be hierarchically porous. The activated carbon substrate may be selected from the group consisting of an activated carbon cloth or a hydrophilic carbon paper (Toray Carbon Paper 060). The activated carbon cloth may be lab- synthesized or a carbon cloth that is activated in a laboratory (as discussed below).

[0202] There is also provided a method for producing said catalyst. While existing methods can take hours to produce conventional OER catalysts, the present method may provide such catalysts within seconds, and facilitate the synthesis of phosphates or phosphides with different crystalline structures by simply controlling the reaction temperature and heating dwell. The method is universal and can be readily adapted to create amorphous or cry stalline metal phosphates / phosphides by using different transition metal salts, which would allow optimization of the overall catalytic perfonnance and stability for water electrocatalysis, as well as other forms of green energy production and storage.

[0203] Provided herein is a method of preparing a catalyst comprising: a compound of Formula (I),

[0204] M Y — (I), wherein:

[0205] M is a transition metal cation, the transition metal selected from the group consisting of cobalt (Co), iron (Fe), nickel (Ni), copper (Cu), cerium (Ce), lanthanum (La), zinc (Zn), palladium (Pd), tungsten (W), molybdenum (Mo) and combinations thereof, and

[0206] Y is an anion selected from phosphate (PO ) and or phosphide (P3); and an activated carbon substrate, wherein the compound is disposed on the activated carbon substrate the method comprising the steps of: a) mixing a salt of M with a phosphorus source in a solvent to form a precursor solution; b) applying the precursor solution on the activated carbon substrate; and c) heating the precursor solution and the activated carbon substrate for a period of about 0.25 ms to about 10 s to form said catalyst.

[0207] Advantageously, the method as disclosed herein may be performed quickly, and may7be completed within seconds. Further advantageously, the disclosed method may readily give access to catalysts with different amorphous or crystalline structures, as well as be readily adapted to utilize different transition metal salts. The method may also advantageously utilize cheap, non-toxic, and widely available starting materials.

[0208] The phosphorus source in said mixing step a) may be selected from the group consisting of phytic acid and phosphoric acid.

[0209] The salt of M in said mixing step a) may be a salt selected from the group consisting of halides, sulfates, acetates and nitrides.

[0210] Tire solvent of said mixing step a) may be selected from the group consisting of ethanol, hydrochloric acid (HC1), water, and combinations thereof. The inventors have surprisingly7found that the selection of a solvent from this group may advantageously provide excess Cl’ anions for solubilization of the transition metal salt, therefore facilitating the formation of the precursor solution.

[0211] Tn some embodiments where M is a combination of at least two transition metals, the precursor solution formed in said mixing step a) is then a mixture of their corresponding salts. In such cases, M may be a combination of transition metal cations as shown in Formula (II), [MWNTNTM5]1’- —(II).

[0212] The precursor solution applied on the activated carbon substrate in said applying step b) is then the mixture of the two or more transition metal salts and not as separate transition metal salts formed in separate precursor solutions.

[0213] For example, M1, M2, M3, M4or M5may each individually be present in the precursor solution at an atomic ratio in a range of about 0.05 to about 0.95, from about 0.05 to about 0.90, from about 0.05 to about 0.85, from about 0.05 to about 0.80, from about 0.05 to about 0.75, from about 0.05 to about 0.70, from about 0.05 to about 0.65, from about 0.05 to about 0.61, from about 0.05 to about 0.60, from about 0.05 to about 0.55, from about 0.05 to about 0.50, from about 0.05 to about 0.45, from about 0.05 to about 0.43, from about 0.05 to about 0.40, from about 0.05 to about 0.39, from about 0.05 to about 0.35, from about 0.05 to about 0.34, from about 0.05 to about 0.30, from about 0.05 to about 0.25, from about 0.05 to about 0.22, from about 0.05 to about 0.20, from about 0.05 to about 0.15, from about 0.05 to about 0.10, or from about 0.10 to about 0.95, from about 0.15 to about 0.95, from about 0.20 to about 0.95, from about 0.22 to about 0.95, from about 0.25 to about 0.95, from about 0.30 to about 0.95, from about 0.34 to about 0.95, from about 0.35 to about 0.95, from about 0.39 to about 0.95, from about 0.40 to about 0.95, from about 0.43 to about 0.95, from about 0.45 to about 0.95, from about 0.50 to about 0.95, from about 0.55 to about 0.95, from about 0.60 to about 0.95, from about 0.61 to about 0.95, from about 0.65 to about 0.95, from about 0.70 to about 0.95, from about 0.75 to about 0.95, from about 0.80 to about 0.95, from about 0.85 to about 0.95, from about 0.90 to about 0.95, or about 0.05, about 0.10, about 0.15, about 0.20, about 0.22, about 0.25, about 0.30, about 0.34, about 0.35, about 0.39, about 0.40, about 0.43, about 0.45, about 0.50, about 0.55, about 0.60, about 0.61, about 0.65, about 0.70, about 0.75, about 0.80, about 0.85, about 0.90, about 0.95. It is to be appreciated that the above ranges should be interpreted as including and supporting any sub-ranges or discrete values (which may or may not be a whole number) that are within the stated range(s).

[0214] The precursor solution may be applied on the activated carbon substrate in said step b) at a loading in a range of about 5.0 mg to about 10.0 mg, from about 5.0 mg to about 9.5 mg, from about 5.0 mg to about 9.0 mg, from about 5.0 mg to about 8.5 mg, from about 5.0 mg to about 8.0 mg, from about 5.0 mg to about 7.5 mg, from about 5.0 mg to about 7.0 mg, from about 5.0 mg to about 6.5 mg, from about 5.0 mg to about 6.0 mg, from about 5.0 mg to about 5.5 mg, or from about 5.5 mg to about 10.0 mg, from about 6.0 mg to about 10.0 mg, from about 6.5 mg to about 10.0 mg, from about 7.0 mg to about 10.0 mg, from about 7.5 mg to about 10.0 mg, from about 8.0 mg to about 10.0 mg, from about 8.5 mg to about 10.0 mg, from about 9.0 mg to about 10.0 mg, from about 9.5 mg to about 10.0 mg, or about 5.0 mg, about 5.5 mg, about 6.0 mg, about 6.5 mg, about 7.0 mg, about 7.5 mg, about 8.0 mg, about 8.5 mg, about 9.0 mg, about 9.5 mg, about 10.0 mg, or any value or range therein. It is to be appreciated that the above ranges should be interpreted as including and supporting any sub-ranges or discrete values (which may or may not be a whole number) that are within the stated range(s).

[0215] The heating step c) may be conducted at a temperature in a range of about 300 °C to about 4000 °C, from about 300 °C to about 3800 °C, from about 300 °C to about 3600 °C, from about 300 °C to about 3400 °C, from about 300 °C to about 3200 °C, from about 300 °C to about 3000 °C, from about 300 °C to about 2800 °C, from about 300 °C to about 2600 °C, from about 300 °C to about 2400 °C, from about 300 °C to about 2200 °C, from about 300 °C to about 2000 °C, from about 300 °C to about 1800 °C, from about 300 °C to about 1600 °C, from about 300 °C to about 1400 °C, from about 300 °C to about 1200 °C, from about 300 °C to about 1000 °C, from about 300 °C to about 900 °C, from about 300 °C to about 800 °C, from about 300 °C to about 700 °C, from about 300 °C to about 600 °C, from about 300 °C to about 500 °C, from about 300 °C to about 400 °C, or from about 400 °C to about 4000 °C, from about 500 °C to about 4000 °C. from about 600 °C to about 4000 °C, from about 700 °C to about 4000 °C, from about 800 °C to about 4000 °C, from about 900 °C to about 4000 °C, from about 1000 °C to about 4000 °C, from about 1200 °C to about 4000 °C, from about 1400 °C to about 4000 °C, from about 1600 °C to about 4000 °C, from about 1800 °C to about 4000 °C, from about 2000 °C to about 4000 °C, from about 2200 °C to about 4000 °C, from about 2400 °C to about 4000 °C, from about 2600 °C to about 4000 °C, from about 2800 °C to about 4000 °C, from about 3000 °C to about 4000 °C, from about 3200 °C to about 4000 °C, from about 3400 °C to about 4000 °C, from about 3600 °C to about 4000 °C, from about 3800 °C to about 4000 °C, or about 300 °C, about 400 °C, about 500 °C, about 600 °C, about 700 °C, about 800 °C, about 900 °C, about 1000 °C, about 1200 °C, about 1400 °C, about 1600 °C, about 1800 °C, about 2000 °C, about 2200 °C, about 2400 °C, about 2600 °C, about 2800 °C, about 3000 °C, about 3200 °C, about 3400 °C, about 3600 °C, about 3800 °C, about 4000 °C, or any value or range therein. It is to be appreciated that the above ranges should be interpreted as including and supporting any sub-ranges or discrete values (which may or may not be a whole number) that arc within the stated rangc(s).

[0216] The precursor solution and activated carbon substrate may be heated in said heating step c) for a period in a range of about 0.25 ms to about 10 seconds, from about 0.25 ms to about 9 seconds, from about 0.25 ms to about 8 seconds, from about 0.25 ms to about 7 seconds, from about 0.25 ms to about 6 seconds, from about 0.25 ms to about 5 seconds, from about 0.25 ms to about 4 seconds, from about 0.25 ms to about 3 seconds, from about 0.25 ms to about 2 seconds, from about 0.25 ms to about 1 seconds, from about 0.25 ms to about 900 ms, from about 0.25 ms to about 800 ms, from about 0.25 ms to about 700 ms, from about 0.25 ms to about 600 ms, from about 0.25 ms to about 500 ms, from about 0.25 ms to about 450 ms, from about 0.25 ms to about 400 ms, from about 0.25 ms to about 350 ms, from about 0.25 ms to about 300 ms, from about 0.25 ms to about 250 ms, from about 0.25 ms to about 200 ms, from about 0.25 ms to about 150 ms, from about 0.25 ms to about 100 ms, from about 0.25 ms to about 90 ms, from about 0.25 ms to about 80 ms, from about 0.25 ms to about 70 ms, from about 0.25 ms to about 60 ms, from about 0.25 ms to about 50 ms, from about 0.25 ms to about 40 ms, from about 0.25 ms to about 30 ms, from about 0.25 ms to about 20 ms, from about 0.25 ms to about 10 ms, from about 0.25 ms to about 9 ms, from about 0.25 ms to about 8 ms, from about 0.25 ms to about 7 ms, from about 0.25 ms to about 6 ms, from about 0.25 ms to about 5 ms, from about 0.25 ms to about 4.5 ms, from about 0.25 ms to about 4 ms, from about 0.25 ms to about 3.5 ms, from about 0.25 ms to about 3 ms, from about 0.25 ms to about 2.5 ms, from about 0.25 ms to about 2 ms, from about 0.25 ms to about 1.5 ms, from about 0.25 ms to about 1 ms, from about 0.25 ms to about 0.75 ms, from about 0.25 ms to about 0.50 ms, or from about 0.50 ms to about 10 seconds, from about 0.75 ms to about 10 seconds, from about 1 ms to about 10 seconds, from about 1.5 ms to about 10 seconds, from about 2 ms to about 10 seconds, from about 2.5 ms to about 10 seconds, from about 3 ms to about 10 seconds, from about 3.5 ms to about 10 seconds, from about 4 ms to about 10 seconds, from about 4.5 ms to about 10 seconds, from about 5 ms to about 10 seconds, from about 6 ms to about 10 seconds, from about 7 ms to about 10 seconds, from about 8 ms to about 10 seconds, from about 9 ms to about 10 seconds, from about 10 ms to about 10 seconds, from about 20 ms to about 10 seconds, from about 30 ms to about 10 seconds, from about 40 ms to about 10 seconds, from about 50 ms to about 10 seconds, from about 60 ms to about 10 seconds, from about 70 ms to about 10 seconds, from about 80 ms to about 10 seconds, from about 90 ms to about 10 seconds, from about 100 ms to about 10 seconds, from about 150 ms to about 10 seconds, from about 200 ms to about 10 seconds, from about 250 ms to about 10 seconds, from about 300 ms to about 10 seconds, from about 350 ms to about 10 seconds, from about 400 ms to about 10 seconds, from about 450 ms to about 10 seconds, from about 500 ms to about 10 seconds, from about 600 ms to about 10 seconds, from about 700 ms to about 10 seconds, from about 800 ms to about 10 seconds, from about 900 ms to about 10 seconds, from about 1 seconds to about 10 seconds, from about 2 seconds to about 10 seconds, from about 3 seconds to about 10 seconds, from about 4 seconds to about 10 seconds, from about 5 seconds to about 10 seconds, from about 6 seconds to about 10 seconds, from about 7 seconds to about 10 seconds, from about 8 seconds to about 10 seconds, from about 9 seconds to about 10 seconds, or about 0.25 ms, about 0.50 ms, about 0.75 ms, about 1 ms, about 1.5 ms, about 2 ms, about 2.5 ms, about 3 ms, about 3.5 ms, about 4 ms, about 4.5 ms, about 5 ms, about 6 ms, about 7 ms, about 8 ms, about 9 ms, about 10 ms, about 20 ms, about 30 ms, about 40 ms, about 50 ms, about 60 ms, about 70 ms, about 80 ms, about 90 ms, about 100 ms, about 150 ms, about 200 ms, about 250 ms, about 300 ms, about 350 ms, about 400 ms, about 450 ms, about 500 ms, about 600 ms, about 700 ms, about 800 ms, about 900 ms, about 1 seconds, about 2 seconds, about 3 seconds, about 4 seconds, about 5 seconds, about 6 seconds, about 7 seconds, about 8 seconds, about 9 seconds, about 10 seconds, or any value or range therein. It is to be appreciated that the above ranges should be interpreted as including and supporting any sub-ranges or discrete values (which may or may not be a whole number) that are within tire stated range(s).

[0217] The inventors have surprisingly found that heating the precursor solution together with the activated carbon substrate may advantageously lead to the formation of a thin layer of the compound that may homogeneously be coated on the activated carbon substrate, which may lead to advantageous properties such as superior electron transport, as well as an increased number of active sites. The inventors have also surprisingly found that by heating the precursor solution together with the activated carbon substrate, the compound and the activated carbon substrate may be bonded together via heat-induced bonding, which may advantageously minimize electrical contact resistance via intimate contact and lead to improved OER performance.

[0218] The heating step c) may take place via Joule heating or laser annealing. The inventors have surprisingly found that Joule heating may produce a catalyst comprising an amorphous compound as a film, while laser annealing may produce a catalyst comprising a crystalline compound as particles, which may be phosphide in VfP form. The inventors have also surprisingly found that when the temperature of heating step c) is higher than about 500 °C, and / or when the heating period is higher than about 100 ms, the catalyst formed may be cry stalline.

[0219] Where Joule heating is used, the Joule heating may take place at a voltage of about 20V to about 30V, or at a power of about 50 W to about 400 W.

[0220] The Joule heating may take place at a dwell time in a range of about 0.05 seconds to about 10.0 seconds, from about 0.05 seconds to about 9.5 seconds, from about 0.05 seconds to about 9.0 seconds, from about 0.05 seconds to about 8.5 seconds, from about 0.05 seconds to about 8.0 seconds, from about 0.05 seconds to about 7.5 seconds, from about 0.05 seconds to about 7.0 seconds, from about 0.05 seconds to about 6.5 seconds, from about 0.05 seconds to about 6.0 seconds, from about 0.05 seconds to about 5.5 seconds, from about 0.05 seconds to about 5.0 seconds, from about 0.05 seconds to about 4.5 seconds, from about 0.05 seconds to about 4.0 seconds, from about 0.05 seconds to about 3.5 seconds, from about 0.05 seconds to about 3.0 seconds, from about 0.05 seconds to about 2.5 seconds, from about 0.05 seconds to about 2.0 seconds, from about 0.05 seconds to about 1.5 seconds, from about 0.05 seconds to about 1.0 seconds, from about 0.05 seconds to about 0.9 seconds, from about 0.05 seconds to about 0.8 seconds, from about 0.05 seconds to about 0.7 seconds, from about 0.05 seconds to about 0.6 seconds, from about 0.05 seconds to about 0.5 seconds, from about 0.05 seconds to about 0.4 seconds, from about 0.05 seconds to about 0.3 seconds, from about 0.05 seconds to about 0.2 seconds, from about 0.05 seconds to about 0.1 seconds, or from about 0.1 seconds to about 10.0 seconds, from about 0.2 seconds to about 10.0 seconds, from about 0.3 seconds to about 10.0 seconds, from about 0.4 seconds to about 10.0 seconds, from about 0.5 seconds to about 10.0 seconds, from about 0.6 seconds to about 10.0 seconds, from about 0.7 seconds to about 10.0 seconds, from about 0.8 seconds to about 10.0 seconds, from about 0.9 seconds to about 10.0 seconds, from about 1.0 seconds to about 10.0 seconds, from about 1.5 seconds to about 10.0 seconds, from about 2.0 seconds to about 10.0 seconds, from about 2.5 seconds to about 10.0 seconds, from about 3.0 seconds to about 10.0 seconds, from about 3.5 seconds to about 10.0 seconds, from about 4.0 seconds to about 10.0 seconds, from about 4.5 seconds to about 10.0 seconds, from about 5.0 seconds to about 10.0 seconds, from about 5.5 seconds to about 10.0 seconds, from about 6.0 seconds to about 10.0 seconds, from about 6.5 seconds to about 10.0 seconds, from about 7.0 seconds to about 10.0 seconds, from about 7.5 seconds to about 10.0 seconds, from about 8.0 seconds to about 10.0 seconds, from about 8.5 seconds to about 10.0 seconds, from about 9.0 seconds to about 10.0 seconds, from about 9.5 seconds to about 10.0 seconds, or about 0.05 seconds, about 0.1 seconds, about 0.2 seconds, about 0.3 seconds, about 0.4 seconds, about 0.5 seconds, about 0.6 seconds, about 0.7 seconds, about 0.8 seconds, about 0.9 seconds, about 1.0 seconds, about 1.5 seconds, about 2.0 seconds, about 2.5 seconds, about 3.0 seconds, about 3.5 seconds, about 4.0 seconds, about 4.5 seconds, about 5.0 seconds, about 5.5 seconds, about 6.0 seconds, about 6.5 seconds, about 7.0 seconds, about 7.5 seconds, about 8.0 seconds, about 8.5 seconds, about 9.0 seconds, about 9.5 seconds, about 10.0 seconds, or any value or range therein. It is to be appreciated that the above ranges should be interpreted as including and supporting any sub-ranges or discrete values (which may or may not be a whole number) that are within the stated range(s).

[0221] Where laser annealing is used, the laser annealing may be performed with a COz laser, an IR laser, or a visible excitation laser. Laser annealing may cause the heating step c) to advantageously be performed at a higher temperature and shorter dwell time as compared to Joule heating.

[0222] The laser annealing may take place at a power of about 1 W to about 100 W, or at a power of about 1W to about 20 W.

[0223] The laser annealing step may take place at a dwell time in a range of about 0.25 ms to about 250 ms, from about 0.25 ms to about 200 ms, from about 0.25 ms to about 150 ms, from about 0.25 ms to about 100 ms, from about 0.25 ms to about 90 ms, from about 0.25 ms to about 80 ms, from about 0.25 ms to about 70 ms, from about 0.25 ms to about 60 ms, from about 0.25 ms to about 50 ms, from about 0.25 ms to about 40 ms, from about 0.25 ms to about 30 ms, from about 0.25 ms to about 20 ms, from about 0.25 ms to about 10 ms, from about 0.25 ms to about 9 ms, from about 0.25 ms to about 8 ms, from about 0.25 ms to about 7 ms, from about 0.25 ms to about 6 ms, from about 0.25 ms to about 5 ms, from about 0.25 ms to about 4.5 ms, from about 0.25 ms to about 4 ms, from about 0.25 ms to about 3.5 ms, from about 0.25 ms to about 3 ms, from about 0.25 ms to about 2.5 ms, from about 0.25 ms to about 2 ms, from about 0.25 ms to about 1.5 ms, from about 0.25 ms to about 1 ms, from about 0.25 ms to about 0.75 ms, from about 0.25 ms to about 0.50 ms, or from about 0.50 ms to about 250 ms, from about 0.75 ms to about 250 ms, from about 1 ms to about 250 ms, from about 1.5 ms to about 250 ms, from about 2 ms to about 250 ms, from about 2.5 ms to about 250 ms, from about 3 ms to about 250 ms, from about 3.5 ms to about 250 ms, from about 4 ms to about 250 ms, from about 4.5 ms to about 250 ms, from about 5 ms to about 250 ms, from about 6 ms to about 250 ms, from about 7 ms to about 250 ms, from about 8 ms to about 250 ms, from about 9 ms to about 250 ms, from about 10 ms to about 250 ms, from about 20 ms to about 250 ms, from about 30 ms to about 250 ms, from about 40 ms to about 250 ms, from about 50 ms to about 250 ms, from about 60 ms to about 250 ms, from about 70 ms to about 250 ms, from about 80 ms to about 250 ms, from about 90 ms to about 250 ms, from about 100 ms to about 250 ms, from about 150 ms to about 250 ms, from about 200 ms to about 250 ms, or any value or range therein. It is to be appreciated that the above ranges should be interpreted as including and supporting any sub-ranges or discrete values (which may or may not be a whole number) that arc within the stated rangc(s).

[0224] Provided herein is a catalyst obtained or obtainable by the method as disclosed herein The catalyst may be as defined above. Provided herein is an electrode comprising the catalyst as disclosed herein. The catalyst may be as defined above.

[0225] The electrode may be used in applications such as water splitting, metal air batteries, supercapacitors, and fuel cells.

[0226] Examples

[0227] Non-limiting examples of the invention and comparative examples will be further described in greater detail by reference to specific examples, which should not be construed as in any way limiting the scope of the invention.

[0228] Example 1: Preparation of catalysts

[0229] All chemicals are used as received. Iron(IIT) chloride (fcCl v6l PO. reagent grade, 97%), nickel(TI) chloride hexahydrate (NiC12’6H2O, ACS reagent, 98%), cobalt(II) chloride hexahydrate (COCI2 6H2O, ReagentPlus), commercial R11O2 (99.9 trace metals basis), phytic acid solution (50% (w / w) in water) and tetramethylammonium hydroxide solution (TMAOH, 25 wt% in water) were purchased from Sigma- Aldrich (United States of America). Absolute ethanol (EtOH) and hydrochloric acid fuming (HO, 37%) was purchased from Supelco (United States of America). KOH (99.99%) was supplied by Aladdin Scientific (United States of America). Commercial AvCarb carbon cloth (AvCarb 1071 HCB) was purchased from Fuel Cell Earth (United States of America) and used after activation treatment.

[0230] Activation of carbon cloth

[0231] The carbon cloth was first immersed in 7 M KOH solution at room temperature for 24 hours and then dried in a vacuum oven at 60 °C. Subsequently, the KOH-infused carbon cloth was pyrolyzed under nitrogen at 800 °C for 2 hours (ramp rate of 5 °C / min) and naturally cooled. The heat-treated KOH-infused carbon cloth was rinsed thoroughly with deionized water until a pH of ~7 was reached. Finally, the activated carbon cloth (ACC) was rinsed with EtOH and dried at ambient temperature in a vacuum oven overnight before use.

[0232] Deposition of precursor solutions

[0233] Metal salts, phytic acid and 37% HC1 were dissolved in ethanol to prepare precursor solutions.

[0234] Using the CoFeNiPi@ACC for Joule heating as an example. 119 mg of CoC12’6H2O, 88 mg of FeC13-6H2O, and 149 mg ofNiC12'6H2O were separately dissolved in a mixed solvent comprising 9 mL of EtOH and 1 mL 37% HC1 in individual vials. Subsequently, 0.23 mL of phytic acid was added to each metal salt solution to form the metal salt / phytic acid precursor solution. By combining 1 mL aliquots of the respective metal salt / phytic acid precursor solutions, a ternary' metal salt / phytic acid precursor solution with total volume of 3 mL was obtained.

[0235] Using the CoCuFcNiPd@ACC for laser irradiation as another example. PdCh solution was prepared by dissolving 8.9 mg of PdCT in the mixture containing 0.9 ml of ethanol and 0.1 ml of 37%HC1 solution. 0.2 ml of PdCl2solution, 0.02 ml 0.05M FeCL ethanol solution, 0.02 ml of 0.05M CoCl2’6H2O ethanol solution, 0.02 ml of 0.05M CuCl2-2H2O ethanol solution and 0.06M NiCL’bHzO ethanol solution were mixed and metal precursors mixture was obtained. Then 23 pl of 50% phytic acid aqueous solution was added into above metal precursors mixture to form metal / phytic acid solution. Next, 0.3 mL of the ternary or quinary metal salt / phytic acid precursor solution was dropcast onto the ACC (25 mm length x 10 mm width), followed by drying at 60 °C on a hotplate. It is noted that the ternary precursor loading on the ACC substrate was approximately 6.8 ±1.3 mg, based on measurements from 5 samples.

[0236] Joule heating

[0237] A piece of the ACC deposited with the metal salt / phytic acid precursor was placed between two metal clips that were connected to a DC power source. The precusor samples were then electrically heated for 100 ms at -420 °C, measured with a Raytek Raynger 3i Plus thermal infrared sensor (Fig. 1). The dashed line represents the results obtained from polynomial regression analysis using the data points. The horizonal and vertical dashed-dotted lines indicate the estimated temperature for a 100 ms heating time is -420 °C. The loading of CoFeNiPi on the ACC substrate was approximately 4.6 ± 1.1 mg, based on measurements from 5 samples, after Joule heating.

[0238] Laser heating

[0239] A continuous wave 532 nm semiconductor laser was focused to a line beam profile with fiill-width- half-maximum (FWHM) of 0.1 mm by 0.4 mm. A piece of the ACC deposited with the metal salt / phytic acid precursor was placed in a custom-built chamber with a quartz window under flowing nitrogen and irradiated at laser powers of 1 to 12 W. The laser was scanned across the samples via dynamic sample stage motion for heating dwells of 0.25 to 250 ms.

[0240] Example 2: Characterization of phosphate (Pi)-based catalysts

[0241] Electrochemical measurements

[0242] All electrochemical measurements were performed using a CHI760E electrochemical workstation under ambient conditions with a standard thrcc-clcctrodc configuration. The setup was consisted of the CoFeNiPi@ACC sample as the working electrode, a platinum mesh as the counter electrode, and a calibrated Hg / HgO electrode as the reference electrode. All ACC-based working electrodes were sandwiched between two pieces of hydrophobic carbon papers to minimize the influence of capillary wetting effects and to isolate them from the platinum clamp holder. RuCh ink as a control was prepared by dispersing 5 mg of commercial RuO> in 1.0 mL of a solution mixture consisting of 0.75 mL EtOH, 0.23 mL deionized water, and 0.02 mL of 5 wt% Nafion solution. The mixture was ultrasonicated for 1 hour to obtain a homogenous ink. Approximately 0.2 mL of the RuO? ink was then dropcast onto the ACC substrate (-1 cm2area) and allowed to dry under ambient conditions prior to electrochemical measurements. To activate the electrocatalysts, cyclic voltammetry (CV) measurements in the potential range of 1.2 to 2.0 V versus reversible hydrogen electrode (RHE) were conducted at a scan rate of 100 mV s ' for 60 cycles.

[0243] All potentials were recorded with respect to the RHE and ( / / -compensated according to eq. (1),

[0244] ERHE - Eng / Hgo + 0. 0592 x pH — IR (1)

[0245] Linear sweep voltammetry experiments were conducted in an alkaline aqueous medium (1.0 M KOH) with a scan rate of 1 mV s ' . The overpotential (y) was determined by r / = — 1. 23 (V). The

[0246] Tafel slope values were determined from the polarization curves using eq. (2), where a, R. F, n, and T represent the overpotential, current density', exchange current density, charge transfer coefficient, gas constant, Faraday constant, number of charge carriers and temperature, respectively. The Tafel slope, represented by 2. 303RT / anF, were determined experimentally obtained by plotting the overpotential / against the logarithm of current density (log / ).

[0247] Electrochemical impedance spectroscopy (EIS) measurements were performed over a frequency range from 1 Hz to 100 kHz.

[0248] Electrochemical surface area (ECSA) values were obtained using the double-layer capacitance method. The double-layer capacitance (Cai) is calculated from CV measurements in non-Faradaic regions at scan rates ranging from 20 to 120 mV s ' based on eq. (3), (3) where ierepresents the charging current and v denotes the scan rate. U is calculated from CV measurements at multiple scan rates using eq. (4), (4) where / anodic an d / cathodic denote the anodic and cathodic current densities at open circuit voltage, respectively. Plotting icas a function of v generates a line with a slope equal to C'di. ECSA was calculated from eq. (5), (5) where Q represents the specific capacitance, typically assumed to have a value of 40 pF cm2in alkaline media.

[0249] The long-term stability of CoFeNiPi@ACC samples was evaluated through chronopotentiometry measurements for a total of 100 hours with a current density' of 10 mA cm2.

[0250] General characterization procedures

[0251] Wide-angle x-ray scattering (WAXS) measurements were performed using a Xcnocs NanoinXidcr instrument in transmission mode using Cu Karadiation source and Dectris Pilatus 3 detectors. All samples were held on the sample holder using Kapton tape

[0252] Scanning electron microscopy (SEM) images were taken on a JEOL 7600F field emission scanning electron microscope equipped with a half-in-lcns detector. Samples were mounted on carbon tape for SEM characterization.

[0253] Transmission electron microscopy (TEXT), selected area electron diffraction (SAED), high-angle annular dark field scanning TEM (HAADF-STEM), and energy-dispersive spectroscopy (EDS) were conducted using a JEOL-21 OOF electron microscope operating at 200 kV, equipped with a Gatan Ultrascan 1000XP CCD camera, Gatan Digiscan and STEM detectors, and an EDAX EDS detector. The metal phosphate@ACC sample was ground with an agate mortar and pestle and redispersed in 1 ml of EtOH. After ultrasonication for 30 seconds, the ethanolic solution was dropcast on a Mo-based grid for TEM characterization.

[0254] The EDS mapping was obtained with a windowless 100 mm2Oxford Ultim Max Silicon Drift Detector.

[0255] X-ray photoelectron spectroscopy (XPS) measurements were conducted using an AXIS Supra spectrometer (Kratos Analytical, UK) equipped with a hemispherical analyzer and a monochromatic Al Kci source (1487 eV) operating at 15 mA and 15 kV. The XPS data were obtained from an analysis area of 700 x 300 pm2at a take-off angle of 90°. Pass energies of 160 and 20 eV were used for survey and high resolutions scans, respectively, with a 3.1 V bias applied to prevent charge build-up on the samples.

[0256] Raman spectra were obtained using a WTTec Alpha300 RS with a 488 nm excitation laser source.

[0257] Water contact angles measurements were obtained using a Dataphysics OCA15 system.

[0258] Inductively coupled plasma optical emission spectroscopy (ICP-OES) was conducted using an Avio 550 Max ICP-OES (Perkin Elm er). Sample solutions were measured after being filtered through a 0.22 pm PTFE filter. An ICP multi -element standard solution IV (Supelco) was used for calibration.

[0259] Characterization of CoFeNiPi&ACC catalyst

[0260] As mentioned in Example 1, a precursor solution (2) in the fonn of CoFeNiPi precursor solution containing phytic acid was dropcasted on an activated carbon substrate (1) in the form of activated carbon cloth fibers to form the CoFeNiPi precursor solution on the activated carbon cloth fibers (3), which is then subjected to transient Joule heating to form amorphous CoFeNiPi coated on activated carbon cloth fibers (CoFeNiPi@ACC) (4), as depicted in the schematic in Fig. 2a. Chloride salts of Co, Ni and Fe were mixed with phytic acid (as the P source) in EtOH and HO acid (providing excess CU for solubilization), and then deposited on the superhydrophilic ACC by drop-casting

[0261] The precursors underwent rapid thermal treatment via resistive Joule heating at -420 °C for a dwell time of 100 ms, leading to interdiffusion of metal cations and the formation of metal -phosphate (M-Pi) bonds to fonn the CoFeNiPi@ACC catalyst (4). As a result of the moderate heating temperature, short heating time and rapid quenching, the resulting CoFeNiPi@ACC exhibited aunifonn coating thickness of -165 nm (Figs. 2b and 4) with an amorphous structure (Figs. 2c and 2d).

[0262] To illustrate the superhydrophilicity of the ACC, water contact angle measurements were conducted on ACC and unactivated carbon cloth. The water droplet contact angle on the unactivated carbon cloth remained -139.8° even after a waiting time of 26 seconds (Figs. 3a and 3b), indicating its hydrophobic nature. In contrast, water droplets completely wet the surface of ACC in less than 0.2 seconds (Figs. 3c and 3d), confirming that ACC is superhydrophilic. It should be noted that the superhydrophilic nature of ACC not only improves the precursor coating but also enhances wetting properties with the electrolyte, potentially leading to enhanced mass transport of charged ionic species during electrocatalysis.

[0263] Electron microscopy and X-ray scattering were employed to evaluate the film morphology, structure, and composition of CoFeNiPi@ACC. Scanning electron microscopy (SEM) images in Fig. 2b show a relatively smooth CoFeNiPi surface morphology, albeit with regular pits and short cracks (see inset), likely due to some degree of thermal-induced contraction after quenching. The high-resolution transmission electron microscopy (HR-TEM) image in Fig. 2c reveals only long-range, well-aligned graphitic carbon sheets, with the notable absence of other crystalline lattice fringes. This observation was corroborated by the selected area electron diffraction (SAED) pattern (inset in Fig. 2c), exhibiting two diffuse rings ascribed to the ACC fibers and indicated the amorphous nature of the resulting CoFeNiPi layer.

[0264] As a control experiment, similar surface morphologies were observed for single metal Co phosphate (CoPi@ACC) and binary metal CoFe phosphate (CoFePi@ACC) after Joule heating (Figs. 5a- 5d). The wide-angle X-ray scattering (WAXS) spectra of uncoated ACC, CoPi@ACC, CoFePi@ACC and CoFeNiPi@ACC were remarkably similar, showing only two broad peaks around the angular positions of 25° and 43°, attributed to graphitic carbon (Fig. 2d). Taken together, HR-TEM, SAED and WAXS unambiguously confirm the amorphous nature of metal phosphates on ACC fibers after Joule heating. Energy-dispersive spectroscopy (EDS) mapping analysis in high-angle annular dark field scanning TEM (HAADF-STEM) mode, shown in Fig. 2e, confirmed the homogeneous elemental distribution of Co, Fe, Ni, 0 and P on the ACC fiber. Table 1 shows that Co, Fe and Ni each have nearly equal atomic concentrations, ranging from 1 to 2 at.%, while the ratio of P to O is about 1:4.

[0265] Table 1. Atomic percentages of CoFcNiPift ACC as determined by HAADF-STEM EDS.

[0266] Element CoFeNiPi@ACC CoFeNiPi@ACC-24h

[0267] Ni 1.84 2.16

[0268] Co 1.73 1.60

[0269] Fe 2.36 2.12

[0270] P 18.29 4.12

[0271] 0 75.78 89.99

[0272] X-ray photoelectron spectroscopy (XPS) provided further insights into the valence and chemical bonding of all elements in the CoFeNiPi@:ACC samples, as shown in Figs. 6a-6f. The 2p core level spectra for Co (Fig. 6a), Fe (Fig. 6b), and Ni (Fig. 6c) were deconvoluted by applying appropriate constraints on their 2p3 / 2and 2pv2spin-orbit components. This included accounting for any overlapping LMM Auger signals from the other metals and the shake-up satellite features. Distinct peaks were observed for Co27Co3-O-P at binding energies of 783.5 and 781.9 eV, for Fe27Fe3-O-P at 710.5 and 713.5 eV, and forNi2+ / Ni3+-O-P at 856.7 and 857.7 eV in the 2p3 / 2region of Co 2p, Fe 2p, and Ni 2p, respectively. These observations confirm the formation of a mixed-metal phosphate structure, ft is interesting to note that the presence of phosphates with mixed oxidation states (2+ and 3+) indicates the oxidation of Co2+, Fe2+, and Ni2+species from the salt precursors during the Joule heating treatment.

[0273] The 0 Is spectrum in Fig. 6d shows a peak at 531.9 eV, suggesting the combined effect of C=O and non-bridging P=O groups, while a peak at 533 eV indicates the contribution of both C-0 and P-0 groups. The P 2p spectrum in Fig. 6c displays peaks at 134.5 eV and 135.4 eV, assigned to the P-O-mctal (metal phosphate) bond and PO3ion, respectively. Notably, the peak at —129 eV, associated with the metal-P (metal phosphide) bond, is absent, indicating that phosphate was the only species formed after the Joule heating treatment. The atomic concentrations of all elements closely matched those found in the EDS analysis, with metals ranging between 1 to 2 at.%, and the ratio of P to 0 was approximately 1:3.2 (Table 2). Finally, the carbon-oxygon bonds at binding energies of 285.5 eV, 286.7 eV and 288.9 eV were observed in the C is spectrum (Fig. 6f). These may be attributed to oxygen-containing hydrophilic groups (such as epoxide, carbonyl, and carboxyl) on the carbon fiber or to adventitious carbon contamination. Table 2. Atomic percentages of CoFeNiPi@:ACC as determined by XPS.

[0274] Example 3: Evaluation of phosphate (Pi)-based catalysts

[0275] Electrocatalytic PER evaluation

[0276] After confirming the amorphous structure and chemical states of the Joule heating-induced CoFcNiPi@ACC, its electrocatalytic performance for OER was evaluated in a 1.0 M KOH electrolyte using a standard three -electrode configuration. Fig. 7a displays the polarization curves of the ternary metallic phosphate CoFeNiPi@ACC and, for comparison, the amorphous metal phosphates of CoFePi@ACC and CoPi@ACC, both prepared by Joule heating, alongside the benchmark RuO2@ACC and uncoated ACC support. CoFeNiPi@ACC exhibited the best OER performance, requiring only an overpotential of 235 mV to drive a current density of 10 mA cm2. CoFePi@ACC followed closely with an overpotential of 257 mV, and CoPi@ACC was significantly higher at 389 mV. In contrast, the control RUO2@ACC required an overpotential of 332 mV to achieve the same current density'. This indicates that amorphous CoFeNiPi unproved the overpotential by almost 30% at 10 mA cm2compared to RuCK The summary' bar charts in Fig. 7b consistently show that CoFeNiPi@ACC required lower overpotentials of 258 and 267 mV to drive current densities of 50 and 100 mA cm2. respectively, compared to CoFePi@ACC (280 and 296 mV) and CoPi@ACC (410 and 430 mV). Although the uncoated ACC substrate exhibited negligible OER activity in the alkaline medium, its superhydrophilicity' and high porosity can facilitate mass transport and fast elimination of generated bubbles under high current densities, preventing charged ionic species from being blocked from the active catalytic sites. Moreover, an oxidation peak at around 1.35 V was observed in the polarization curve of amorphous CoFeNiPi@ACC, which can be attributed to the oxidation of either Co2or Ni2+.

[0277] Fig. 7c displays Tafel slope values extracted from the Tafel region of the linear sweep voltammetry curves, which were used to assess the OER activity kinetics. Both amorphous CoFeNiPi@ACC and CoFePi@ACC catalysts exhibited similar, low Tafel slopes of 32.2 and 32.3 mV dec1, respectively, indicating rapid OER surface kinetics. In contrast, the unary metallic CoPi@ACC showed a higher Tafel slope of 45.8 mV dec1. suggesting that the inclusion of Fe and Ni metal cations synergistically enhances the OER kinetics. Notably, the benchmark RuOz@ACC catalyst had the highest Tafel slope value of 1 18.9 mV dec1. Figs. 8a and 8b present the polarization curves of other amorphous unary and binary metallic phosphate combinations prepared via Joule heating, among which the amorphous CoFeNiPi@ACC catalyst consistently exhibits the highest OER activity. Further control experiments were conducted by Joule heating ternary' metal precursors for extended dwell times of 250 and 500 ms at higher temperatures of -820 and 1 140 °C, respectively, resulting in the formation of cry stalline materials as shown by the appearance of new reflections in Fig. 9. The polarization curve and Tafel slope plots presented in Figs. 10a and 10b clearly show that the CoFeNiPi@ACC catalyst, when Joule-heated for a shorter dwell of 100 ms, exhibited the lowest overpotential (267 mV at 100 mA cm2) and Tafel slope (32.2 mV dec ' ) for OER. Specifically, to drive a 100 mA cm2current density, the overpotential value of amorphous CoFeNiPi@ACC is the lowest (267 mV), compared to crystalline CoFeNi-P@ACC-250 (298 mV) and crystalline CoFeNi-P@ACC-500 (319 mV). Additionally, the amorphous CoFeNiPi@ACC has the lowest Tafel slope (32.2 mV dec1), compared to the crystalline CoFeNi-P@ACC-250 (37.8 mV dec1) and crystalline CoFeNi-P@ACC-500 (47.9 mV dec1). These excellent performance metrics are attributed to its amorphous structure, in contrast to its crystalline counterparts, which were heated for 250 ms (298 mV and 37.8 mV dec1) and 500 ms (319 mV and 47.9 mV dec1).

[0278] Electrochemical impedance spectroscopy (EIS) provided further insights into the surface reaction kinetics and charge carrier transfer of the amorphous metal phosphate catalysts. Fig. 7d shows the Nyquist plots and the equivalent circuit resistance (inset) for all amorphous metal phosphate catalysts over the frequency range from 1 Hz to 100 kHz. The ternary metallic phosphate FeCoNiPi@ACC exhibited the lowest charge transfer resistance (Rci) at 0.22 Q, compared to CoFePi@ACC at 0.57 fl and CoPi@ACC at 0.89 fl This underscores the significant roles of Fe and Ni in enhancing electroconductivity and facilitating surface charge transfer kinetics.

[0279] To corroborate that the enhanced OER performance of amorphous metal phosphates is due to intrinsic activity improvement, the electrochemical active surface areas (ECSA) were calculated using cyclic voltammetry (CV) curves in the non-Faradaic region measured at scan rates ranging from 20 to 120 mV s ' (Figs. 1 la to 11c). Fig. 7e displays the double-layer capacitance (Cdi) values of amorphous metal phosphate catalysts on the ACC substrate, obtained from the plots of Aj / 2 versus CV scan rate. Both CoFeNiPi@ACC and CoFePi@ACC exhibited similar Cdi values of 17.2 and 15.7 mF cm;. respectively, indicating comparable ECSA values of 430 and 392.5 CIUECSA2and similar numbers of active sites. Although CoPi@ACC had the highest Cdi at 65.9 mF cm \ corresponding to the highest ECSA of 1648 CHIECSA2and largest number of active sites, it exhibited the lowest OER activity. This underscores that the enhanced intrinsic activities of the amorphous multi-mctallic phosphate combinations, particularly CoFeNiPi@ACC, were responsible for their remarkable OER performance. Fig. 12 presents the specific activities normalized by ECSA ( / ECSA) of the amorphous metal phosphate catalysts. CoFeNiPi@ACC exhibited the highest specific activity of 0.129 mA cniEcsA~2at the OER overpotential of 270 mV, which was 3.5 and 117.3 times higher than CoFePi@ACC (0.037 mA emu s.-,:) and CoPi@ACC (0.0011 mA cnii r sA2). respectively.

[0280] Finally, long-term stability tests were conducted on the Joule-heated amorphous metal phosphates. Fig. 7g shows the chronopotentiometry experiment of the amorphous CoFeNiPi@ACC at a current density of 10 mA cm2. which maintained a relatively stable OER overpotential of 250 mV at the 100 hour timepoint. The robustness of the catalyst may have benefited from the formation of the amorphous metal phosphate structure and the oxidation of Co2+and Ni2+to higher valence states during Joule heating. To test this hypothesis, linear sweep voltammetry and chronopotentiometry experiments were perforated on the metal salts / phytic acid precursor coated on the ACC substrate (precursor@ACC). Fig. 13 displays the polarization curves for precursor@ACC samples in two states: upon activation and after immersion in 1 M KOH for 3 hours. Both samples showed pronounced oxidation peaks at 1.44 V, indicating the oxidation of cations from Ni2+to Ni3+. In contrast, this anodic peak is significantly less evident in the polarization curve of the amorphous CoFcNiPm ACC sample, suggesting that most metal cations were already in the 3+ state due to prior Joule heating process. While the precursor@ACC exhibited comparable polarization behavior to the amorphous metal phosphate catalyst (Fig. 13), the performance of the precursor working electrode degraded rapidly after the first 3 hours of chronopotentiomctry. indicating poor stability (Fig. 14). This degradation is attributed to the weak interaction forces within the precursor coating, causing physical disintegration during continuous OER operation in 1 M KOH. To test this hypothesis, both precursor@ACC and amorphous CoFeNiPi@ACC samples were immersed in 1 M KOH for 3 hours. ICP- OES analysis detected leached Fe species solely from the precursor@ACC sample (Table 3), confirming that Joule heating is essential for forming the amorphous phosphate structure, oxidizing metal cations, and stabilizing the coating through heat treatment at 420 °C for a brief 100 ms.

[0281] Surface reconstruction

[0282] The preoxidation of Co2+and Ni2+to higher valence states and the formation of Co and Ni oxyhydroxides are crucial steps in OER. The pseudocapacitive behaviors of amorphous metal phosphates were investigated by analyzing their CV profiles to determine the influence of the transient Joule heating process and composition on oxyhydroxide generation. Fig. 15a illustrates the first and second CV cycles conducted on CoPi@ACC, CoFcPi@ACC, CoNiPi@ACC, and CoFcNiPi@ACC overthe range from 0.85 to 1.55 V. Initially, all samples displayed larger pseudocapacitive charges in the first cycle than in the second, suggesting irreversible surface reconstruction and oxyhydroxide evolution. Tn addition, the pseudocapacitive charges were notably similar between CoPi@ACC and CoFePi@ACC, as well as between CoNiPi@ACC and CoFeNiPi@ACC.

[0283] For the CoPi@ACC catalyst, an anodic peak at 1.02 V observed in the first cycle indicates the oxidation of Co2+to CoOOH. Notably, this transformation occurred at a significantly lower potential compared to other reported Co-based oxides, indicating that Joule heating facilitated the preoxidation of Co2+to higher oxidation states. A second, smaller anodic peak at 1.01 V in the subsequent cycle suggested a lesser degree of surface reconstruction in CoPi@ACC. The addition of other metals shifted the anodic peaks for Co2+oxidation to 1.09 V in CoFePi@ACC and 1.05 V in CoNiPi@ACC. However, the absence of the Co oxidation peak in the second cycles of both CoFePi@ACC and CoNiPi@ACC suggested complete surface reconstruction involving Co. Additionally, in CoNiPi@ACC, another anodic peak at 1.38 V observed in the first cycle was attributed to the oxidation of Ni2+and formation of NiOOH, with a smaller subsequent peak at 1.32 V in the second cycle indicating a lesser degree of surface reconstruction involving Ni.

[0284] Unlike the single and binary metal-based phosphate cataly sts, CoFeNiPi@ACC exhibited only the 1.33 V and 1.40 V anodic peaks in the first cycle, attributed to Ni2+oxidation and no detectable peak for Co oxidation. This absence shows that substituting Co with Ni or Fe facilitates Co2+preoxidation. The result was further corroborated by the presence of Co3+in the XPS spectrum of Co 2p (Fig. 6a), confirming that Joule heating and the addition of Ni and Fe enhanced the preoxidation of Co2+. Similarly, the presence of smaller anodic peaks at 1.32 V and 1.36 V in the second cycle indicated reduced surface reconstruction.

[0285] Raman spectroscopy provided further insights into structural and compositional changes in the catalysts. Fig. 15b shows the Raman spectra of the amorphous CoFcNiPi@ACC in various states: as-made immediately right after Joule heating, upon activation, and after chronopotentiometry for 24 and 100 hours. The Raman spectrum of the as-made CoFeNiPi@ACC exhibited a strong reflection at 1020 cm1and another broad, low-intensity peak around 630 cm '. attributed to the symmetric stretching mode of PO4 and P-O-P symmetric-stretching mode, respectively. However, the activated CoFeNiPi@ACC sample displayed a significantly broader band in the 400 to 700 cm range, featuring component reflections corresponding to 7-CoOOI I (461, 514 and 661 cm ') and P-CoOOH (501 cm and 602 cm-1), FeOOH (696 cm2),.and NiOOH (475 and 557 cm2) The presence of y-CoOOH and P-CoOOH signals suggests some locally structured regions within the activated catalyst. After chronopotentiomctry for 24 and 100 hours, both the CoFeNiPi@ACC-24h and CoFcNiPi@ACC-100h exhibited a smoother broad band in the 450 to 700 cm1range (Fig. 15b). The Raman reflection at 1020 cm1had almost completely disappeared, indicating the breakdown of phosphate groups and surface restructuring into the respective oxyhydroxides. Fig. 16 shows that the Raman spectra of the unary and binary metal phosphates, CoPi and CoFePi, exhibited similar signals of y-CoOOH, P- CoOOH and FeOOH. Notably, the signal intensity of y-CoOOH at 661 cm is significantly reduced in the CoFePi and CoFeNiPi spectra, as Fe has been reported to inhibit the transformation from the OER-active 3-CoOOH to the less active y-CoOOH structure.

[0286] To determine the changes in elemental compositions and distributions, EDS analysis in line scan analysis was conducted on the amorphous CoFeNiPi@ACC catalyst in its Joule-heated as-made form and after chronopotcntiomctry at a constant current density of 10 mA cm2for 24 and 100 hours. The EDS line scan of the as-made CoFcNiPi@ACC revealed that oxygen varied between 60 to 70 at.%, and phosphorous between 20 to 30 at.% at the surface (Fig. 17a). After 24 hours of chronopotentiometry, the oxygen content increased to 80 to 90 at.%, and phosphorous decreased significantly to less than 10 at.%; indicating surface reconstruction and oxyhydroxide formation (Fig. 15c). Similar chemical compositions were observed after 100 hours of chronopotentiometry (Fig. 17b). WAXS analysis confirmed that the catalysts remained amorphous (Fig. 18), and SEM showed some surface roughening (Figs. 19a to 19d).

[0287] XPS analysis of the CoFeNiPi catalyst after 24 hours of chronopotentiometry verified the formation of CoOOH, FeOOH and NiOOH species on the electrocatalyst surface. High-resolution XPS spectra displayed in Fig. 6 reveal notable shifts to lower binding energies in the component peaks of Co 2p, Ni 2p and Fe 2p. Specifically, peaks at 779.8 eV, 712.6 eV and 857.0 eV are assigned to Co 2ps / 2 for Co3+-OOH (Fig. 6a), Fe 2p3« for Fe3+-OOH (Fig. 6b), and Ni 2ps / 2 for Ni3+-OOH (Fig. 6c), respectively. In the O Is spectrum, peaks at 532.6 eV, 531.0 eV and 528.9 eV correspond to C-O, M-OH, and M-O, respectively, indicating the predominant formation of active oxyhydroxides, NiOOH and CoOOH (Fig. 6d). In addition, a weak P-0 signal at 133.2 eV was observed in the P 2p spectrum, likely from residual oxidized phosphorus species doped into the ACC fiber (Fig. 6e). Quantitative XPS analysis showed that the phosphorus content on the ACC fiber surface decreased significantly to -0.43 at.%. (Table 2), contrasting with EDS results that showed a bulk phosphorous composition of -4.12 at.% (Table 1). This reduction in surface phosphate groups, accompanied by the formation of a substantial amount of active NiOOH and CoOOH, is attributed to dynamic surface reconstruction during OER. The changes in surface composition also suggest the release of some metal ions into the electrolyte during the reconstruction process. The above findings indicate that the phosphate group can promote tire formation of active oxyhydroxides, NiOOH and CoOOH. It should be mentioned that FeOOH is unlikely to actively participate in the OER, as FePi@ACC is the least active catalyst among all unary metallic phosphates as shown in Fig. 8. Further XPS analy sis of CoFeNiPi catalyst after 100 hours of chronopotentiometry confirmed that the signals of Co, Fe, Ni, O and P remained almost unchanged compared to the data of the 24-hour chronopotentiometry' sample (Figs. 20a to 20e).

[0288] The amorphous phosphate catalyst was also subjected to linear sweep voltammetry experiments in tetramethylammonium hydroxide (TMAOH) electrolyte to determine the OER pathway. The TMA+cation acts as a chemical probe to detect the presence of OF species, which arc considered key intermediates in the lattice oxygen mechanism (LOM) pathway. Fig. 21a shows the OER polarization curves and Fig 21b shows the Tafel slopes of CoFeNiPi@ACC in 1 .0 M TMAOH compared to that in 1 M KOH. Both CoFeNiPi@ACC samples exhibited highly similar OER polarization activities and kinetics, indicating negligible lattice oxygen contribution and suggesting that the OER pathway follows the adsorbate evolution mechanism (AEM). Example 4: Characterization of phosphide (P)-based catalysts

[0289] CoFeNiP@ACC was prepared according to the procedure described in Example 1, except with a dwell time ranging from 0.25s to 2.5s.

[0290] Fig. 22 shows SEM and WAXS data of crystalline CoFeNiP@ACC samples heated for a longer duration of 0.25 to 2.5 s. Figs. 22a, 22b, and 22c show the formation of crystalline nanoparticles on the carbon fibers, with typical nanoparticle sizes ranging from tens of nanometers to around 1 pm. The crystalline structure was corroborated by WAXS, as shown in Fig. 22d, suggesting a metal phosphide solid solution of M2P and M12P5 structures.

[0291] Fig. 23 shows the polarization curves of the resulting crystalline CoFcNiP@ACC samples for OER. The sample that was annealed for 0.25 s (CoFeNiP@ACC-0.25s) exhibited the lowest overpotential of 254 mV to drive a current density of 10 mA cm2. However, as the Joule heating dwell time increased, the catalytic activities of the respective CoFeNiP@ACC samples (CoFeNiP@ACC-0.5s and CoFeNiP@ACC-2.5s) decreased, requiring higher overpotentials of 263 and 289 mV to achieve current density of 10 mA cm2. This may be due to the increase in nanoparticle size and reduction in the number of active sites.

[0292] As an alternative to Joule heating, it was demonstrated that laser annealing at powers of 4 to 6 W and dwell times of 2.5 to 15 ms resulted in the formation of crystalline high entropy metal phosphide nanoparticlcs as M2P form (M: CoCuFcNiPd), as shown in the SEM (sec Figs. 24a to 24f) and WAXS data (see Fig. 24g).

[0293] Example 5:Quinary metal-phosphorus catalysts

[0294] Following the synthesis and characterization of ternary’ metal-phosphorus catalysts, a quinary metal salt / phytic acid precursor was used as described in Example 1 to produce CoCuFeNiW-P compound catalysts by Joule heating for 100 and 500 ms, respectively.

[0295] WAXS measurements (Fig. 25a) confirms that CoCuFeNiWPi@ACC and CoCuFeNiW-P@ACC- 500ms remained predominantly amorphous, thereby displaying the wide applicability of the method in synthesizing catalysts with five metals. Further, the polarization curves and the Tafel plots presented in Figs. 25b and 25c clearly for these catalysts remain in a competitive range and exhibit exemplary OER performance.

[0296] A summary of the electrocatalysts synthesized and characterized in the above Examples is found in Table 4.

[0297] Table 4: Structural and electrochemical properties of phosphorus -containing OER catalysts from Joule heating and laser annealing in alkaline media

[0298] Electrocatalyst Metal Precursor Structure T]iu / mV Tafel slope

[0299] Atomic Ratio (at. %) / mV dec1

[0300] CoPi@ACC Co: 100% Amorphous 389 45.8

[0301] CoFePi@ACC Co: 61%, Fe: 39% Amorphous 257 32.2

[0302] CoFeNiPi@ACC Co: 34%, Fe: 22%, Amorphous 235 32.2

[0303] Ni: 43

[0304] Comparative Examples

[0305] Comparative Example 1: Phosphorus-containing OER Catalysts

[0306] The OER performance of the Joule-heated amorphous CoFeNiPi@ACC was compared with other known phosphorus-containing OER catalysts, demonstrating its leading performance as characterized by low overpotential and small Tafel slope values (Fig. 7f and Table 5).

[0307] Table 5: Summary of the OER performance of comparative embodiments of phosphorus-containing electrocatalysts in alkaline media.

[0308] As can be seen from Table 5, the CoFeNiPi@ACC exhibited the lowest overpotential and Tafel slope values as compared to the other known electrocatalysts. It can thus be concluded that electrocatalysts of the present invention exhibit superior catalytic properties among other phosphorus-containing electrocatalysts.

[0309] Industrial Applicability

[0310] The present invention relates to catalysts for use in electrochemical reactions and methods of making such catalysts. Tire catalyst may be used in applications such as water splitting, metal air batteries, supercapacitors, and fuel cells.

[0311] It will be apparent that various other modifications and adaptations of the invention will be apparent to the person skilled in the art after reading the foregoing disclosure without departing from the spirit and scope of the invention and it is intended that all such modifications and adaptations come within the scope of the appended claims.

Claims

Claims1. A catalyst comprising: a compound of Formula (I), M Y — (I), wherein:M is a transition metal cation, the transition metal selected from the group consisting of cobalt (Co), iron (Fe), and nickel (Ni), copper (Cu), cerium (Ce), lanthanum (La), zinc (Zn), palladium (Pd), tungsten (W), molybdenum (Mo) and combinations thereof, andY is an anion selected from phosphate (POT ) or phosphide (P3); and an activated carbon substrate, wherein the compound is disposed on the activated carbon substrate.

2. The catalyst of claim 1, wherein the atomic ratio of M to Y is in the range of about 1:0.5 to about 1:5.

3. The catalyst of claim 1 or 2, wherein M is a combination of transition metal cations as shown in Formula (II),wherein M1and M2are each individually present at an atomic ratio in the range of about 0.05 to about 0.95, M _ M4, and M5are each individually absent or present at an atomic ratio in the range of 0.05 to about 0.95, and 5 < n < 15.

4. The catalyst of any one of claims 1 to 3, wherein the compound is amorphous or crystalline.

5. The catalyst of any one of claims 1 to 4, wherein the compound is disposed on the activated carbon substrate in the form of a film or as particles.

6. The catalyst of claim 5, wherein the film has a thickness of about 50 nm to about 1000 nm.

7. The catalyst of claim 5, wherein the particles each independently has a particle size of about 10 nm to about 10 pm.

8. The catalyst of any one of claims 1 to 7, wherein the compound disposed on the activated carbon substrate is bonded to the activated carbon substrate via heat-induced bonding.

9. The catalyst of any one of claims 1 to 8, wherein the compound is disposed on the activated carbon substrate homogeneously.

10. The catalyst of any one of claims 1 to 9, wherein M is selected from the group consisting of Co, CoFc, CoFeNi, CoCuFeNiPd, and FeCoNiCuMo 11. The cataly st of any one of claims 1 to 10, wherein the activated carbon substrate is superhydrophilic .

12. The catalyst of any one of claims 1 to 11, wherein the activated carbon substrate is hierarchically porous.

13. A method of preparing a catalyst comprising: a compound of Formula (I),M Y — (I), wherein:M is a transition metal cation, the transition metal selected from the group consisting of cobalt (Co), iron (Fe), nickel (Ni), copper (Cu), cerium (Ce), lanthanum (La), zinc (Zn), palladium (Pd), tungsten (W), molybdenum (Mo) and combinations thereof, andY is an anion selected from phosphate (PO ) and or phosphide (P3); and an activated carbon substrate, wherein the compound is disposed on the activated carbon substrate the method comprising the steps of: a) mixing a salt of M with a phosphorus source in a solvent to form a precursor solution; b) applying the precursor solution on the activated carbon substrate; and c) heating the precursor solution and the activated carbon substrate for a period of about 0.25 ms to about 10 s to form said catalyst.

14. The method of claim 13, wherein the phosphorus source in said mixing step a) is selected from the group consisting of phytic acid and phosphoric acid.

15. The method of claim 13 or 14, wherein the salt of M in said mixing step a) is a salt selected from the group consisting of halides, sulfates, acetates and nitrides.

16. The method of any one of claims 13 to 15, wherein said heating step c) is conducted at a temperature of about 300 °C to about 4000 °C.

17. The method of any one of claims 13 to 16, wherein about 5 mg to about 30 mg of the precursor is applied on the activated carbon substrate in said applying step b) .

18. The method of any one of claims 13 to 17, wherein the solvent of said mixing step a) is selected from the group consisting of ethanol, hydrochloric acid (HQ), water, and combinations thereof.

19. The method of any one of claims 13 to 18, wherein said heating step c) takes place via Joule heating or laser annealing.

20. The method of claim 19, wherein the Joule heating takes place at a voltage of about 10V to about 50V, or at a power of about 50 W to about 400 W.

21. The method of claim 19 or 20, wherein the Joule heating takes place at a dwell time of about 50ms to about 10 s.

22. The method of claim 22, wherein the laser annealing takes place with a laser at a power of about 1 W to about 100 W.

23. The method of claim 22, wherein the laser annealing is performed with a visible excitation laser or infrared laser.

24. The method of claim 19 or 23, wherein the laser annealing step takes place at a dwell time of about 0.25 ms to about 250 ms.

25. A catalyst obtained or obtainable by the method of any one of claims 14 to 24.

26. An electrode comprising the catalyst of any one of claims 1 to 13 and 25.

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