Oxyhydroxide non-metal-doped electrocatalyst, method for manufacturing same, and water electrolysis battery or air battery comprising same

Abstract

One embodiment of the present invention provides an electrocatalyst comprising a hybrid composite including MXene and layered double hydroxide (LDH), wherein the hybrid composite is partially doped with fluorine. The electrocatalyst of the present invention can be used as a catalyst material of a positive electrode in a metal air battery or an anion exchange membrane water electrolysis system, and has excellent electrochemical performance and stability.

Description

Oxyhydroxide nonmetal-doped electrocatalyst, method for manufacturing the same, and water electrolytic cell or air cell containing the same

[0001] The present invention relates to an electrocatalyst, and more specifically, to an oxyhydroxide nonmetal doped electrocatalyst that can be used in electrochemical energy conversion devices such as water electrolysis cells and metal-air batteries.

[0002] In the development of electrochemical energy conversion and storage devices such as water electrolysis cells and metal-air batteries, the development of high-efficiency oxide electrode materials capable of overcoming poor catalytic kinetics and high overpotential by effectively inducing the four-electron oxygen evolution reaction (OER) must be prioritized.

[0003] In the case of ruthenium oxide (RuO2) and iridium oxide (IrO2), which are conventionally used as water oxidation electrodes, their low economic feasibility and poor stability act as major obstacles to the commercialization of electrochemical devices.

[0004] To overcome this, research on two-dimensional bimetallic double-layer hydroxides, which can provide many active sites through synergistic effects between heterogeneous metal elements, unique electronic structure, large interlayer distance, and large specific surface area, is actively continuing.

[0005] However, these bimetallic double-layer hydroxides have limitations such as low electrical conductivity, strong self-cohesion, high energy barriers for active site formation, and long-term operational stability.

[0006] In addition, in the case of metal-air batteries, there is a problem in that bifunctionality regarding OER and oxygen reduction reaction (ORR) for charging and discharging must be ensured.

[0007] [Prior Art Literature]

[0008] (Patent Document 0001) Republic of Korea Registered Patent Publication No. 10-2470597

[0009] The present invention provides a non-metal-doped bimetal double-layer hydroxide-MXene hybrid catalyst that ensures excellent performance and stability in electrochemical energy conversion and storage devices, such as water electrolysis cells and metal-air batteries, as a method to solve the problems of the aforementioned prior art.

[0010] The technical problems that the present invention aims to solve are not limited to those mentioned above, and other unmentioned technical problems will be clearly understood by those skilled in the art to which the present invention belongs from the description below.

[0011] To achieve the above technical problem, one embodiment of the present invention provides an electrocatalyst.

[0012] A hybrid composite comprising MXene and a layered double hydroxide according to one embodiment of the present invention is included, wherein the hybrid composite is characterized by having a partially doped surface of fluorine.

[0013] In an embodiment of the present invention, the hybrid composite may be an electrocatalyst characterized by having a structure in which the layered double hydroxide is grown on the MXene.

[0014] According to an embodiment of the present invention, excellent water oxidation oxygen generation reaction activity and stability can provide a major turning point in the market for next-generation energy conversion and storage systems, such as water electrolysis cells and metal-air batteries.

[0015] The effects of the present invention are not limited to the effects described above, and should be understood to include all effects that can be inferred from the configuration of the invention described in the detailed description of the invention or the claims.

[0016] FIG. 1 is a drawing showing an electrocatalyst according to one embodiment of the present invention.

[0017] FIG. 2 is a schematic diagram of the synthesis process of an electrocatalyst according to one embodiment of the present invention.

[0018] Figure 3 is a diagram showing the XRD diffraction patterns of LDH / MX and LDH.

[0019] FIG. 4 is a diagram showing the XRD diffraction patterns of an electrocatalyst and a reference material according to one embodiment of the present invention.

[0020] Figure 5a is a TEM image of MXene.

[0021] Figure 5b is a Raman spectrum image of MXene.

[0022] Figure 6a is an SEM image of LDH / MX.

[0023] Figure 6b is an elemental distribution diagram of LDH / MX EDS.

[0024] Figure 7a is a low-magnification SEM image of LDH.

[0025] Figure 7b is a high-magnification SEM image of LDH.

[0026] FIG. 8a is an SEM image of an electrocatalyst according to one embodiment of the present invention.

[0027] FIG. 8b is a TEM image of an electrocatalyst according to one embodiment of the present invention.

[0028] FIG. 8c is an HR-TEM image of an electrocatalyst according to one embodiment of the present invention.

[0029] FIG. 8d is an HR-TEM image of an electrocatalyst according to one embodiment of the present invention.

[0030] FIG. 8e is an HR-TEM image of an electrocatalyst according to one embodiment of the present invention.

[0031] FIG. 8f is an HR-TEM image of an electrocatalyst according to one embodiment of the present invention.

[0032] FIG. 8g is a diagram showing the elemental distribution of an electrocatalyst in EDS according to one embodiment of the present invention.

[0033] FIG. 9a is a figure showing high-resolution XPS spectra (Ni 2p) of an electrocatalyst, LDH / MX, and LDH according to one embodiment of the present invention.

[0034] FIG. 9b is a figure showing high-resolution XPS spectra (Fe 2p) of an electrocatalyst, LDH / MX, and LDH according to one embodiment of the present invention.

[0035] FIG. 9c is a diagram showing the high-resolution XPS spectrum (Ti 2p) of an electrocatalyst, LDH / MX, according to one embodiment of the present invention.

[0036] FIG. 9d is a diagram showing the high-resolution XPS spectrum (F 1s) of an electrocatalyst, LDH / MX, according to one embodiment of the present invention.

[0037] Figure 10 is a diagram showing the repeated OER polarization curve for MXene.

[0038] FIG. 11a is a polarization curve on a glassy carbon substrate electrode for an electrocatalyst, LDH / MX, F-LDH, LDH, and RuO2 according to one embodiment of the present invention.

[0039] FIG. 11b is a Tafel slope diagram for an electrocatalyst, LDH / MX, F-LDH, LDH, and RuO2 according to one embodiment of the present invention.

[0040] FIG. 11c is a polarization curve on a nickel foam substrate electrode for an electrocatalyst, LDH / MX, F-LDH, LDH, and RuO2 according to one embodiment of the present invention.

[0041] FIG. 11d is an electrochemical impedance spectrum for an electrocatalyst, LDH / MX, F-LDH, LDH, and RuO2 according to one embodiment of the present invention.

[0042] FIG. 11e is a TOF graph for an electrocatalyst, LDH / MX, F-LDH, LDH, and RuO2 according to one embodiment of the present invention.

[0043] FIG. 11f is a diagram showing the results of long-term operation stability evaluation and repeated measurement stability evaluation for an electrocatalyst, LDH / MX, F-LDH, LDH, and RuO2 according to one embodiment of the present invention.

[0044] FIG. 12 is a graph of the Tafel slope on a nickel foam substrate electrode for an electrocatalyst, F-LDH, LDH / MX, and LDH according to one embodiment of the present invention.

[0045] FIG. 13a shows 10 mA / cm² according to the substrate electrode for an electrocatalyst, F-LDH, LDH / MX, and LDH according to an embodiment of the present invention. 2 This is a comparison diagram of the overvoltage slope at.

[0046] FIG. 13b is a diagram comparing the Tafel slope according to the substrate electrode for an electrocatalyst, F-LDH, LDH / MX, and LDH according to one embodiment of the present invention.

[0047] Figure 14a is a diagram of the electrochemical active area (ECSA) of LDH.

[0048] Figure 14b is an electrochemical active area (ECSA) diagram of LDH / MX.

[0049] Figure 14c is a diagram of the electrochemical active area (ECSA) of F-LDH.

[0050] FIG. 14d is a diagram of the electrochemical active area (ECSA) of an electrocatalyst according to one embodiment.

[0051] Figure 14e is a comparison diagram of the electrochemical active area (ECSA) of the comparative example and the example.

[0052] Figure 14f is the ECSA reference current density-applied voltage polarization curve of the comparative example and the example.

[0053] Figure 15a is a contact angle analysis diagram of LDH / MX.

[0054] FIG. 15b is a contact angle analysis diagram of an electrocatalyst according to one embodiment of the present invention.

[0055] FIG. 15c is a contact angle analysis diagram of an electrocatalyst according to one embodiment of the present invention supported in 1M KOH.

[0056] FIG. 16a is a TEM image of an electrocatalyst according to one embodiment of the present invention supported in 1M KOH.

[0057] FIG. 16b is an HR-TEM image of an electrocatalyst according to one embodiment of the present invention supported in 1M KOH.

[0058] FIG. 16c is a TEM image of an electrocatalyst according to one embodiment of the present invention after driving an OER reaction in 1M KOH.

[0059] FIG. 16d is an HR-TEM image of an electrocatalyst according to one embodiment of the present invention after driving an OER reaction in 1M KOH.

[0060] FIG. 17 is a figure showing the Raman spectra of LDH / MX, an electrocatalyst (F-LDH / MX) according to one embodiment of the present invention, and F-LDH / MX after an OER reaction in 1M KOH.

[0061] FIG. 18a is the Ni 2p XPS spectrum of LDH / MX, an electrocatalyst (F-LDH / MX) according to one embodiment of the present invention, F-LDH / MX supported on 1M KOH, and F-LDH / MX after OER reaction in 1M KOH.

[0062] FIG. 18b is the Fe 2p XPS spectrum of LDH / MX, an electrocatalyst (F-LDH / MX) according to one embodiment of the present invention, F-LDH / MX supported on 1M KOH, and F-LDH / MX after OER reaction in 1M KOH.

[0063] FIG. 18c is the O 1s XPS spectrum of LDH / MX, an electrocatalyst (F-LDH / MX) according to one embodiment of the present invention, F-LDH / MX supported on 1M KOH, and F-LDH / MX after OER reaction in 1M KOH.

[0064] Figure 19a is the Ni 2p XPS spectrum of F-LDH after OER reaction in LDH, F-LDH, and 1M KOH.

[0065] Figure 19b is the Fe 2p XPS spectrum of F-LDH after OER reaction in LDH, F-LDH, and 1M KOH.

[0066] Figure 19c is the O 1s XPS spectrum of F-LDH after the OER reaction in F-LDH and 1M KOH.

[0067] Figure 19d is the F 1s XPS spectrum of F-LDH after the OER reaction in 1M KOH.

[0068] FIG. 20a is the Ni 2p XPS spectrum of F-LDH and an electrocatalyst according to one embodiment of the present invention after an OER reaction in 1M KOH.

[0069] FIG. 20b is the Fe 2p XPS spectrum of F-LDH and an electrocatalyst according to one embodiment of the present invention after an OER reaction in 1M KOH.

[0070] Figure 21a shows the Ni 2p XPS spectra of LDH / MX before and after 1M KOH loading and after the OER reaction.

[0071] Figure 21b shows the Fe 2p XPS spectra of LDH / MX before and after 1M KOH loading and after the OER reaction.

[0072] Figure 21c shows the O 1s XPS spectra of LDH / MX before and after 1M KOH loading and after the OER reaction.

[0073] FIG. 22a is an OER polarization curve according to pH of LDH, F-LDH, LDH / MX, and an electrocatalyst according to one embodiment of the present invention.

[0074] FIG. 22b is a graph showing the change in current density according to pH of LDH, F-LDH, LDH / MX, and an electrocatalyst according to one embodiment of the present invention.

[0075] Figure 23a shows the driving polarization curves of AEMWE cells for F-LDH / MX || Pt / C and RuO2 || Pt / C with the same commercial reduction electrode (Pt / C).

[0076] Figure 23b is a diagram showing the long-term operation stability evaluation results of an AEMWE cell with F-LDH / MX || Pt / C using the same commercial reduction electrode (Pt / C).

[0077] Figure 23c is a diagram showing the Faraday efficiency of an AEMWE cell with F-LDH / MX || Pt / C using the same commercial reduction electrode (Pt / C).

[0078] FIG. 24a is a schematic diagram of the operation of a zinc-air battery including an electrocatalyst according to one embodiment of the present invention.

[0079] Figure 24b is a diagram showing the open circuit voltages of F-LDH / MX || Pt / C and RuO2 || Pt / C.

[0080] Figure 24c shows the polarization curves of F-LDH / MX || Pt / C and RuO2 || Pt / C.

[0081] Figure 24d is a comparison of power densities of F-LDH / MX || Pt / C and RuO2 || Pt / C.

[0082] Figure 24e is a long-term charge / discharge stability evaluation diagram of F-LDH / MX || Pt / C.

[0083] Figure 25 is a diagram of the long-term charge / discharge stability evaluation of RuO2|| Pt / C.

[0084] The present invention will be described below with reference to the attached drawings. However, the present invention may be implemented in various different forms and is therefore not limited to the embodiments described herein. Furthermore, in order to clearly explain the present invention in the drawings, parts unrelated to the explanation have been omitted, and similar parts throughout the specification have been given similar reference numerals.

[0085] Throughout the specification, when it is stated that a part is "connected (connected, in contact, combined)" with another part, this includes not only cases where they are "directly connected," but also cases where they are "indirectly connected" with other members interposed between them. Furthermore, when it is stated that a part "includes" a certain component, this means that, unless specifically stated otherwise, it does not exclude other components but rather allows for the inclusion of additional components.

[0086] The terms used herein are merely for describing specific embodiments and are not intended to limit the invention. Singular expressions include plural expressions unless the context clearly indicates otherwise. In this specification, terms such as “comprising” or “having” are intended to indicate the presence of the features, numbers, steps, actions, components, parts, or combinations thereof described in the specification, and should be understood as not precluding the existence or addition of one or more other features, numbers, steps, actions, components, parts, or combinations thereof.

[0087] Embodiments of the present invention will be described in detail below with reference to the attached drawings.

[0088]

[0089] An electrocatalyst according to one embodiment of the present invention will be described.

[0090] FIG. 1 is a drawing showing an electrocatalyst according to one embodiment of the present invention.

[0091] An electrocatalyst according to one embodiment of the present invention, with reference to FIG. 1, comprises a hybrid composite comprising MXene and a layered double hydroxide (LDH), wherein the hybrid composite is partially doped with fluorine (F).

[0092] The present invention relates to a high-efficiency oxidation electrode material capable of effectively inducing an oxygen evolution reaction (hereinafter OER), and provides an electrocatalyst that can be used as an electrode material in, for example, a water electrolysis cell or a metal-air battery.

[0093] In particular, by 2D / 2D hybridization of a two-dimensional bimetallic layered double hydroxide (LDH) that exhibits high activity in water oxidation reactions and MXene, a two-dimensional material with excellent electrical conductivity, strong interfacial interactions and enhanced ion diffusion can be induced, thereby providing an electrode material capable of providing efficient active sites.

[0094] In particular, the present invention enables the induction of a highly efficient water oxidation generation reaction by additionally adopting fluorine (F) doping. This will be described later.

[0095] In an embodiment of the present invention, the hybrid composite may have a structure in which a layered double hydroxide is grown on a MXene, in the form of a heterostructure of MXene and a layered double hydroxide.

[0096] The above MXene is Ti3C2T x It corresponds to a two-dimensional material with high electrical conductivity represented by the chemical formula.

[0097] At this time, the above T may be one or more selected from O, OH, and F.

[0098] The above layered double hydroxide (LDH) refers to a divalent metal cation having six OH groups in an octahedral form. - It is surrounded by, and some of the divalent metal cations are substituted by trivalent metal cations, corresponding to a hydroxide having a two-dimensional layered structure in which the surface carries a positive charge. At this time, the positive charge on the surface of the layered double hydroxide structure is due to anions (A) existing between the layered structures. m- It can be offset by ).

[0099] At this time, the chemical formula of the layered double hydroxide is, [M 2+ 1-x M 3+ x (OH)2] x+ [(A m- )] x / m It can be expressed as [nH2O]. In the above chemical formula, M is a divalent cation. 2+ It can be composed of metals such as Co, Mg, Ni, Cu, and Zn, and M is a trivalent cation 3+ It can be composed of metals such as Al, Fe, V, Ti, and Ga. In addition, A inserted between the layers m- is Cl - , NO 3- , SO4 2- Various organic and inorganic anions can be formed. In addition, in the above chemical formula, x is a number greater than 0 and less than 1, m is an integer from 1 to 4, and n is a number from 0.1 to 15.

[0100] At this time, it may be preferable for the MXene in the composite to be included in an amount of 5 to 10 wt%, and for the surface-doped fluorine to be included in an amount of 10 to 30 wt%, preferably 20 wt%. If the content of the MXene is lower than the range described above, a decrease in stability due to self-aggregation and a decrease in activity due to poor electrical properties may occur, and if the content of the MXene is excessive, poor catalytic properties may appear because it fails to provide sufficient oxygen evolution reaction active sites. In addition, if the fluorine doping is performed at a level lower than the range described above, poor catalytic properties may appear because it fails to provide sufficient oxygen evolution reaction active sites, and if the fluorine doping is excessive, it may impair the stability of the catalyst material.

[0101]

[0102] Next, a method for manufacturing an electrocatalyst according to one embodiment of the present invention will be described.

[0103] A method for manufacturing an electrocatalyst according to one embodiment of the present invention comprises: a step of preparing a MXene dispersion solution (S100); a step of preparing a layered double hydroxide precursor solution (S200); a step of mixing and reacting the MXene dispersion solution and the precursor solution to produce a MXene-layered double hydroxide hybrid composite (S300); and a step of mixing and reacting the composite with a fluorine precursor to produce a fluorine partially doped hybrid composite (S400).

[0104] First, prepare a MXene dispersion solution (S100).

[0105] The above MXene is Ti3C2T x It corresponds to a two-dimensional material having high electrical conductivity represented by the chemical formula, and the fact that T can be one or more selected from O, OH, F is the same as above.

[0106] There are no special restrictions on the solvent included in the above solution, and for example, NMP (N-methyl pyrrolidone) can be used.

[0107] The above MXene may be, for example, obtained by adding MAX phase particles to a hydrofluoric acid solution and performing selective etching to obtain a MXene dispersion solution.

[0108] Next, a layered double hydroxide precursor solution is prepared (S200).

[0109] The double hydroxide precursor solution may be in the form of a hydrate of a metal element included in the layered double hydroxide. For example, in an embodiment of the present invention to be described later in which Ni and Fe are adopted as metal elements, the precursors used were Ni(NO3)2·6H2O and Fe(NO3)3·9H2O, respectively. Additionally, the precursor solution may further include urea as an additive.

[0110] Next, after preparing the complex, fluorine doping is performed (S300, S400).

[0111] In the above S300 step, the composite is manufactured through a hydrothermal synthesis method. The layered double hydroxide precursor solution and the MXene solution described above are mixed and then reacted. The reaction may be carried out under an inert gas atmosphere, and the temperature range may preferably be 80°C to 130°C.

[0112] In addition, in step S400 above, for fluorine doping, a fluorine precursor such as NH4F may be used, and the reaction may be carried out under an inert gas atmosphere, and the temperature range to induce surface doping is preferably 120°C to 180°C, more preferably 150°C. In addition, compared to the composite prepared in step S300 above, it is preferable that the fluorine precursor be mixed and reacted in a mass ratio of 1:4 to 6 (complex:fluorine precursor).

[0113]

[0114] Meanwhile, the present invention is characterized primarily by the fact that the heterostructure composite described above is fluorine-doped. The fluorine doping increases oxygen vacancies and promotes activation into oxyhydroxide (-OOH), thereby inducing a high-efficiency water oxidation oxygen evolution reaction, so that the finally obtained catalyst can provide a water electrolysis cell or metal-air battery with excellent performance.

[0115] The electrocatalyst according to one embodiment of the present invention produced through the above fluorine doping (Example 2, F-LDH / MX to be described later) exhibits a lower Tafel slope and overpotential compared to Example 1 (LDH / MX) in which fluorine doping was not performed, confirming that it is an excellent electrocatalyst for oxygen evolution.

[0116]

[0117] The present invention will be explained in more detail below through manufacturing examples, comparative examples, and experimental examples. However, the present invention is not limited to the following manufacturing examples and experimental examples.

[0118]

[0119] Example: Synthesis of LDH / MX and F-LDH / MX

[0120] FIG. 2 is a schematic diagram of the synthesis process of an electrocatalyst according to an embodiment of the present invention. Hereinafter, the synthesis process of an embodiment of the present invention will be described with reference to FIG. 2.

[0121]

[0122] (1) MXene synthesis

[0123] The MXene used in the experiment was prepared by placing 2.0 g of Ti3AlC2 particles into 20 mL of hydrofluoric acid solution and carrying out the reaction at 50 °C for 36 hours to perform selective Al etching. Afterward, the material was washed by centrifuging several times with deionized water and freeze-dried.

[0124] Subsequently, MXine (MX) was synthesized by mixing 0.6g of powdered sample with 12mL of dimethyl sulfoxide (DMSO) at room temperature for 18 hours and ultrasonically dispersing for 4 hours, followed by washing with deionized water through several centrifugations.

[0125]

[0126] (2) LDH / MXene (LDH / MX) synthesis

[0127] The synthesized MXene above was prepared by dispersing 10 mL of MXene dispersion (7 mg / mL) in 30 mL of N-methyl pyrrolidone (NMP). Separately, Ni(NO3)2·6H2O (3 mmol), Fe(NO3)3·9H2O (1.5 mmol), and urea (12.0 g) were prepared by dissolving them in 20 mL of deionized water.

[0128] The two solutions were mixed and the reaction was carried out for 5 hours at 100°C under an Ar atmosphere. Afterward, the heterostructure complex LDH / MX (Example 1) was synthesized by washing through several centrifugations using deionized water.

[0129]

[0130] (3) Synthesis of partially fluorinated LDH / MXene (F-LDH / MX)

[0131] The above-described synthesized LDH / MX and NH4F (mass ratio LDH / MX:NH4F=1:5) were prepared. F-LDH / MX (Example 2) was synthesized by carrying out the reaction in a tubular electric furnace at 150°C for 2 hours in an Ar atmosphere with NH4F positioned upstream.

[0132]

[0133] Comparative Example: LDH and F-LDH

[0134] As a comparative example, the previously prepared MXene (hereinafter MX, Comparative Example 1), LDH synthesized without a MXene support (Comparative Example 2), and F-LDH (Comparative Example 3) were prepared.

[0135] LDH and F-LDH were prepared using the same method, excluding the MXene precursor solution in the LDH / MX synthesis step.

[0136]

[0137] Experimental Example 1: Confirmation of structural changes in catalysts according to examples and comparative examples

[0138] SEM, TEM, XRD, and Raman analysis were performed for structural analysis of Examples 1 to 2 and Comparative Examples 1 to 3.

[0139] Figure 3 is a diagram showing the XRD diffraction patterns of LDH / MX and LDH.

[0140] FIG. 4 is a diagram showing the XRD diffraction patterns of an electrocatalyst and a reference material according to one embodiment of the present invention.

[0141] In the XRD comparing LDH (Comparative Example 2) and LDH / MX (Example 1) of Figure 3 above, only the peak indicating LDH was observed due to the low content of MXene.

[0142] On the other hand, as shown in Figure 4 above, in the XRD of F-LDH / MX (Example 2), peaks indicating LDH at 12.64°, 34.25°, and 61.19° appeared, along with new peaks indicating cubic FeF3 and (NH4)(NiF3) and (NH4)3FeF6 at 14.84°, 28.63°, 29.91°, 45.76°, 50.00°, 52.26°, 59.49°, and 64.30°. Through this, it was confirmed that a partial fluorination reaction successfully occurred on the surface of F-LDH / MX.

[0143]

[0144] Figure 5a is a TEM image of MXene, and Figure 5b is a Raman spectrum image of MXene.

[0145] Figure 6a is an SEM image of LDH / MX, and Figure 6b is an elemental distribution diagram of LDH / MX in EDS.

[0146] In FIG. 5a above, the (0110) plane of Ti3C2MXene was identified through a multi-layered two-dimensional MXene nanosheet structure and a lattice spacing of 0.269 nm, and in FIG. 5b above, it was confirmed through Raman spectra that two-dimensional Ti3C2MXene (Comparative Example 1) with various functional groups was synthesized.

[0147] In addition, through Figures 6a and 6b above, it was confirmed that LDH with a thickness of 20 nm grew in a direction perpendicular to the MXene in LDH / MX (Example 1), and it was confirmed that the elements constituting it consist of Fe, Ni, C, Ti, and O.

[0148]

[0149] Figure 7a is a low-magnification SEM image of LDH, and Figure 7b is a high-magnification SEM image of LDH.

[0150] As shown in Figure 7 above, it was confirmed that the manufactured LDH (Comparative Example 2) has a two-dimensional plate-like structure.

[0151]

[0152] FIG. 8a is an SEM image of an electrocatalyst (Example 2) according to one embodiment of the present invention, FIG. 8b is a TEM image, FIG. 8c to 8f are HR-TEM images, and FIG. 8g is an EDS elemental distribution diagram.

[0153] In Figures 8a and 8b above, the three-dimensional shape formed through 2D / 2D hybridization can be confirmed without significant difference in nano-shape in the SEM and TEM images of F-LDH / MX (Example 2) after surface partial fluorination of LDH / MX.

[0154] In addition, in FIGS. 8c to 8f, FeNi-LDH of the (012) plane, (NH4)(NiF3) of the (204) plane, FeF3 of the (333) plane, and (NH4)3(FeF6) of the (400) plane can be identified through interplanar lattice distances corresponding to 0.250 nm, 0.209 nm, 0.199 nm, and 0.224 nm, respectively, and it can be confirmed that this is consistent with the XRD (Fig. 4a) results.

[0155] In addition, through the elemental distribution image shown in Figure 8g, it was confirmed that the elements constituting F-LDH and MXene, F, Fe, Ni, C, Ti, and O, are evenly distributed.

[0156]

[0157] FIGS. 9a to 9d are drawings showing high-resolution XPS spectra of an electrocatalyst, LDH / MX, and LDH according to an embodiment of the present invention (Fig. 9a: Ni 2p, Fig. 9b: Fe 2p, Fig. 9c: Ti 2p, Fig. 9d: F 1s).

[0158] Through the high-resolution XPS spectra of Comparative Example 2 (LDH) and Examples 1 and 2 (LDH / MX and F-LDH / MX) in Figure 9 above, it can be confirmed that charge redistribution occurred due to strong interfacial interactions between LDH and MXene, and new peaks indicating Ni-F and Fe-F bonds appeared after surface partial fluorination.

[0159] This means that the strong electron affinity of fluorine can induce high oxidation states of Ni and Fe, thereby exhibiting effective OER characteristics. In addition, the surface partial fluorination reaction was successfully induced through the Ti-F peak and F 1s spectrum, along with the aforementioned Ni-F and Fe-F bonding in F-LDH / MX (Example 2), and the intermediate adsorption characteristics for OER were improved by effectively inducing high valence states of metal elements.

[0160]

[0161] Experimental Example 2: Analysis of Electrochemical OER Activity and Mechanism

[0162] Evaluation and comparative analysis of electrochemical OER activity with commercial catalyst RuO2 (Comparative Example 4) for the synthesized examples and comparative examples were performed in a 1M KOH electrolyte.

[0163] Figure 10 is a diagram showing the repeated OER polarization curve for MXene.

[0164] In the above Figure 10, it was confirmed that MXene does not exhibit activity for electrochemical OER and acts as a conductive substrate that causes changes in the electronic structure of LDH.

[0165]

[0166] FIG. 11 shows (a) polarization curve on a glassy carbon substrate electrode, (b) Tafel slope, (c) polarization curve on a nickel foam substrate electrode, (d) electrochemical impedance spectrum, (e) TOF graph, and (f) long-term operation stability evaluation and repeated measurement stability evaluation results for an electrocatalyst according to one embodiment of the present invention, LDH / MX, a comparative example, and RuO2.

[0167] FIG. 12 is a graph of the Tafel slope on a nickel foam substrate electrode for an electrocatalyst, F-LDH, LDH / MX, and LDH according to one embodiment of the present invention.

[0168] FIG. 13a shows 10 mA / cm² according to the substrate electrode for an electrocatalyst, F-LDH, LDH / MX, and LDH according to an embodiment of the present invention. 2 This is a comparison diagram of the overvoltage slope at.

[0169] FIG. 13b is a diagram comparing the Tafel slope according to the substrate electrode for an electrocatalyst, F-LDH, LDH / MX, and LDH according to one embodiment of the present invention.

[0170] In Fig. 11, F-LDH / MX (Example 2) exhibits the strongest redox peak near the 1.43 V vs. RHE potential, which is consistent with the results observed in XPS, Ni 2+ From Ni 3+ / 4+ It refers to the change in the oxidation number of the element.

[0171] In Fig. 11a, which is an activity evaluation coated on a glassy carbon substrate electrode for precise evaluation of the catalyst's own activity, 10 mA / cm² 2 Based on the overpotential at [location], high activity was observed in the order of F-LDH / MX (251mV), F-LDH (286mV), LDH / MX (302mV), RuO2 (352mV), and LDH (360mV).

[0172] In addition, the Tafel slopes in Figure 11b also showed excellent activity in the order of F-LDH / MX (40.28mV / dec), F-LDH (77.14mV / dec), LDH / MX (88.74mV / dec), RuO2 (112.09mV / dec), and LDH (115.86mV / dec).

[0173] In particular, as can be seen in FIG. 11c and FIG. 12 and FIG. 13, when evaluating the performance of commercially widely used nickel foam as a substrate electrode, it showed superior activity compared to glassy carbon substrate electrodes.

[0174] The charge transfer resistance calculated through the electrochemical impedance spectrum of Figure 11d was also F-LDH / MX (24.97Ω), F-LDH (48.77Ω), LDH / MX (112.5Ω), and LDH (1157Ω), showing that Example 2 (F-LDH / MX) exhibited the best charge transfer behavior.

[0175]

[0176] FIGS. 14a to 14e are comparative drawings of the electrochemical active area (ECSA) for an electrocatalyst, F-LDH, LDH / MX, and LDH according to an embodiment of the present invention.

[0177] FIG. 14f is a current density-applied voltage polarization curve based on electrochemical active area (ECSA) for an electrocatalyst, F-LDH, LDH / MX, and LDH according to one embodiment of the present invention.

[0178]

[0179] Meanwhile, the excellent electrochemical OER activity of F-LDH / MX can also be confirmed in the turnover frequency (TOF) over time in Fig. 11e and the electrochemical active surface area (ECSA) in Figs. 14a to 14f.

[0180]

[0181] Figure 11f shows the polarization curves of F-LDH / MX before and after 1,000 cycles of cyclic voltametry (CV) measurement and the results of 30 hours of constant voltage measurement, which confirm the excellent long-term operation stability and repetitive operation stability of F-LDH / MX.

[0182]

[0183] FIG. 15a is a contact angle analysis diagram of LDH / MX, FIG. 15b is an electrocatalyst according to one embodiment of the present invention, and FIG. 15c is a contact angle analysis diagram of an electrocatalyst according to one embodiment of the present invention using 1M KOH.

[0184] In Fig. 15a, the contact angle of LDH / MX is 135°, whereas in Fig. 15b, the contact angle of F-LDH / MX is 78°, indicating hydrophilic surface characteristics due to partial surface fluorination.

[0185] In particular, when the contact angle of F-LDH / MX using 1M KOH, an AEMWE driving electrolyte, was analyzed (Fig. 15c), the contact angle was found to be 0° even without applying voltage, confirming strong hydrophilic surface characteristics. It can be inferred that these surface characteristics effectively act on the adsorption of hydroxyl groups in the electrolyte, charge transfer at the electrode / electrolyte interface, and bubble diffusion under high current conditions, leading to the manifestation of excellent OER characteristics.

[0186] FIGS. 16a and 16b are TEM and HR-TEM images of an electrocatalyst according to one embodiment of the present invention supported in 1M KOH, and FIGS. 16c and 16d are TEM and HR-TEM images after driving an OER reaction in 1M KOH.

[0187] Figure 17 shows the Raman spectra of LDH / MX, F-LDH / MX, and F-LDH / MX after OER reaction in 1M KOH.

[0188] In Figures 16a and 16b above, in the case of F-LDH / MX supported in 1M KOH, the metal fluoride phase disappears and transitions to an amorphous form occur, and in Figures 16c and 16d, TEM images before and after OER driving confirm that a lattice plane distance of 0.245 nm appears, referring to NiFeOOH in the oxyhydroxide form after current application, in the amorphous form before current application.

[0189] In addition, it can be confirmed that numerous holey defects are formed through the reconstruction of the surface structure of F-LDH / MX following an electrochemical oxidation reaction performed in 1M KOH.

[0190] This surface structure reconstruction can be further confirmed by the appearance of peaks indicating NiOOH and FeOOH in the Raman spectrum of Figure 17 after an electrochemical oxidation reaction performed in 1M KOH.

[0191] Figure 18 shows the (a) Ni 2p, (b) Fe 2p, and (c) O 1s XPS spectra of LDH / MX, F-LDH / MX, F-LDH / MX supported in 1M KOH, and F-LDH / MX after OER reaction in 1M KOH.

[0192] In addition, the XPS spectrum in Fig. 18 showed that the bond between the metal (Ni or Fe) and F of F-LDH / MX supported on 1M KOH was lost, and the surface structure was reconfigured into the form of an oxyhydroxide such as NiFeOOH through an additional electrochemical oxidation reaction.

[0193] Figure 19 shows the (a) Ni 2p, (b) Fe 2p, (c) O 1s, and (d) F 1s XPS spectra of F-LDH after OER reaction in LDH, F-LDH, and 1M KOH.

[0194] Figure 20 shows the (a) Ni 2p and (b) Fe 2p XPS spectra of F-LDH and F-LDH / MX after the OER reaction in 1M KOH.

[0195] Figure 21 shows the XPS spectra of (a) Ni 2p, (b) Fe 2p, and (c) O 1s before and after 1M KOH loading and OER reaction of LDH / MX.

[0196] Figure 22 shows (a) OER polarization curves according to pH and (b) a graph of current density change according to pH for LDH, F-LDH, LDH / MX, and F-LDH / MX.

[0197] In particular, through comparison with the above Figures 19 to 21, it can be confirmed that oxygen vacancies, which are increased due to charge redistribution and surface partial fluorination caused by interfacial interaction with MXene, can promote activation into oxyhydroxide (-OOH).

[0198] In addition, by analyzing the change in current density according to the electrolyte pH in Fig. 22, it can be confirmed that the material presented in the present invention can exhibit excellent OER characteristics following the lattice oxygen participation mechanism (LOM).

[0199]

[0200] Experimental Example 3: Evaluation of Application of Anion Separator Water Electrolyze Cell and Metal-Air Battery

[0201] To compare commercial catalysts RuO2 and F-LDH / MX as oxidation electrodes of anion membrane water electrolysis (AEMWE) cells, an electrolytic cell was constructed using a commercial Pt / C catalyst as the reduction electrode to evaluate performance and stability.

[0202] Figure 23 shows the driving (a) polarization curve, (b) long-term driving stability evaluation, and (c) Faraday efficiency of AEMWE cells of F-LDH / MX || Pt / C and RuO2 || Pt / C using the same commercial reduction electrode (Pt / C).

[0203] As shown in Figure 23 above, when RuO2 was applied, the cell voltage was 1.61 V, whereas for F-LDH / MX, it was 1.528 V, confirming excellent activity superior to commercial catalysts, stability at the 40-hour level, and Faraday efficiency, an indicator of charge transfer efficiency.

[0204]

[0205] FIG. 24a is a schematic diagram of the operation of a zinc-air battery including an electrocatalyst according to one embodiment of the present invention, FIG. 24b is a diagram showing the open-circuit voltage of F-LDH / MX || Pt / C and RuO2 || Pt / C, FIG. 24c is a polarization curve of F-LDH / MX || Pt / C and RuO2 || Pt / C, FIG. 24d is a power density comparison diagram of F-LDH / MX || Pt / C and RuO2 || Pt / C, and FIG. 24e is a long-term charge / discharge stability evaluation diagram of F-LDH / MX || Pt / C.

[0206] In addition, Fig. 25 is a diagram of the long-term charge / discharge stability evaluation of RuO2|| Pt / C.

[0207] As shown in FIGS. 24 and 25 above, when applied as the air electrode of a zinc (Zn)-air battery, a type of metal-air battery, a high open circuit voltage of 1.45 V and a current density (5.1 mA / cm²) of the battery with RuO2 applied 2 (at 2V) and power density (67.68 mW / cm²) 2 25.7 mA / cm², superior compared to 2 Current density at 2V and 75.43 mW / cm² 2 The power density of was shown.

[0208] In addition, the battery with RuO2 showed an initial voltage difference of 1.43V and a round trip efficiency of 41.86%, which increased to a voltage difference of 1.86V and a round trip efficiency of 27.06% after 150 hours of measurement, whereas the battery with F-LDH / MX maintained a voltage difference of 0.83V and a stable round trip efficiency (initial: 57.2%, after 150 hours of measurement: 58.6%) even after 150 hours of charge-discharge measurement, thereby ensuring excellent stability.

[0209]

[0210] The foregoing description of the present invention is for illustrative purposes only, and those skilled in the art will understand that other specific forms can be easily modified without altering the technical spirit or essential features of the present invention. Therefore, the embodiments described above should be understood as illustrative in all respects and not restrictive. For example, each component described as a single unit may be implemented in a distributed manner, and components described as distributed may likewise be implemented in a combined form.

[0211] The scope of the present invention is defined by the claims set forth below, and all modifications or variations derived from the meaning and scope of the claims and equivalent concepts thereof should be interpreted as being included within the scope of the present invention.

Claims

1. A hybrid complex comprising MXene and layered double hydroxide, and The above hybrid composite is an electrocatalyst characterized by having a surface portion fluorine doped.

2. In Paragraph 1, The above hybrid composite is, An electrocatalyst characterized by having a structure in which the layered double hydroxide is grown on the MXene.

3. In Paragraph 1, The above MXene is Ti3C2T x An electrocatalyst represented by the chemical formula, wherein T is O, OH, or F.

4. In Paragraph 1, The above layered double hydroxide is, [M 2+ 1-x M 3+ x (OH)2] x+ [(A m- )] x / m It is represented by the chemical formula [nH2O], and The above M 2+ is Co 2+ , Mg 2+ , Ni 2+ , Cu 2+ and Zn 2+ One or more selected from among the above M 3+ is Al 3+ , Fe 3+ , V 3+ , Ti 3+ and Ga 3+ One or more selected from among the above A m- is Cl - , NO 3- and SO4 2- An electrocatalyst characterized by being one or more selected from among, wherein x is a number greater than 0 and less than 1, m is an integer from 1 to 4, and n is a number from 0.1 to 15.

5. In Paragraph 1, An electrocatalyst characterized in that the MXene content in the above complex is 5 to 10 wt%.

6. In Paragraph 1, An electrocatalyst characterized in that the surface-doped fluorine in the electrocatalyst is 10 to 30 wt%.

7. Step of preparing the MXene dispersion solution; Step of preparing a layered double hydroxide precursor solution; A step of preparing a MXene-layered double hydroxide hybrid composite by mixing and reacting the above-mentioned MXene dispersion solution and precursor solution; and A method for manufacturing an electrocatalyst characterized by including the step of mixing the above-mentioned complex with a fluorine precursor and reacting it to produce a fluorine-partially doped hybrid complex.

8. In Paragraph 7, In the step of manufacturing the above-mentioned fluorine-partially-doped hybrid composite, A method for manufacturing an electrocatalyst characterized by carrying out the above reaction under conditions of an inert gas atmosphere and a temperature range of 120 to 180°C.

9. In Paragraph 7, In the step of manufacturing the above MXene-layered double hydroxide hybrid composite, A method for manufacturing an electrocatalyst characterized by carrying out the above reaction under conditions of an inert gas atmosphere and a temperature range of 80 to 130℃.

10. In Paragraph 7, In the step of manufacturing the above-mentioned fluorine-partially-doped hybrid composite, The above fluorine precursor is NH4F, and A method for manufacturing an electrocatalyst characterized by mixing the above-mentioned complex and a fluorine precursor in a mass ratio of 1:4 to 6 and reacting them to produce a fluorine partially doped hybrid complex.

11. An anode comprising the electrocatalyst of claim 1; cathode; and A metal-air battery characterized by containing an electrolyte.

12. An anode comprising the electrocatalyst of claim 1; cathode; and An anion exchange membrane water electrolysis system characterized by containing an electrolyte.

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