Electrocatalyst for acidic oxygen evolution reaction as well as preparation method and application of electrocatalyst

Abstract

The invention discloses an electrocatalyst for acidic oxygen evolution reaction as well as a preparation method and application of the electrocatalyst, and belongs to the technical field of electrolyzed water. The preparation method of the electrocatalyst for the acidic oxygen evolution reaction comprises the following steps: growing a transition metal oxide on a conductive substrate in situ to obtain a transition metal oxide carrier; the transition metal oxide carrier is subjected to plasma treatment and then placed in a precious metal salt solution for a cation exchange reaction, and the electrocatalyst is obtained. The electrocatalyst prepared by the invention has extremely low initial overpotential (187mV) when a water electrolysis reaction is carried out in a 0.5 M H2SO4 solution, has no obvious performance degradation in a continuous acidic water electrolysis process for 4500h, shows very high operation stability, and has great application potential in the aspects of replacing a commercial RuO2 / IrO2 catalyst and reducing electrode preparation cost and acidic water electrolysis.

Description

Technical Field

[0001] The present invention relates to the technical field of electrolyzed water, and particularly to an electrocatalyst for acidic oxygen evolution reaction, a preparation method thereof, and an application thereof. Background Art

[0002] Water splitting can generate abundant renewable electric energy and is considered an ideal way to produce hydrogen. At present, alkaline water electrolyzers and proton exchange membrane water electrolyzers (PEMWEs) are two mainstream hydrogen production technologies. PEMWEs have attracted worldwide interest because they provide purer H 2 , have a larger current density and higher energy efficiency. The strong acidic operating conditions in commercial PEMWEs require the use of noble metals such as platinum and iridium / ruthenium as electrocatalysts for hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) at the cathode and anode. OER is a four-proton coupled-electron transfer electrochemical reaction, and its reaction energy barrier is higher than that of HER. Currently, noble metals such as ruthenium / iridium-based oxides are usually used as OER electrocatalysts in acidic water electrolyzers. However, the high cost and limited availability of these metals severely limit their widespread use. In addition, RuO 2 and IrO 2 have serious problems of insufficient durability in acidic OER. Therefore, it is still challenging to achieve a balance between low cost and high performance (activity / stability) under acidic conditions.

[0003] Single-atom catalysts (SACs) are a recently emerging type of catalyst that promises to maximize atomic utilization. However, a single active atom determines a single adsorption mode (end-on adsorption), which follows the traditional adsorbate evolution mechanism (AEM), and its activity is limited by the scaling relationship between the adsorption energies of certain intermediates (i.e., *OH, *O, and *OOH) during the oxygen evolution process, resulting in a relatively high theoretical overpotential (370 mV) for the OER process. In practical applications, the catalytic performance is far lower than expected, and the catalytic stability of ruthenium / iridium-based electrocatalysts is improved at the expense of activity. Low-cost transition metal oxides have become efficient support materials for stabilizing active single atoms in electrocatalytic water splitting, especially in acidic water oxidation reactions. However, the weak single-atom-support interaction makes the single-atom-O (support) bond extremely vulnerable to corrosion / dissolution due to enhanced lattice oxygen participation, resulting in severe deactivation under harsh acidic OER conditions. Therefore, there is an urgent need to develop effective strategies to ensure the stability of electrocatalysts without sacrificing activity. Summary of the Invention

[0004] The purpose of the present invention is to provide an electrocatalyst for acidic oxygen evolution reaction, a preparation method thereof, and an application thereof to solve the problems existing in the above-mentioned prior art.

[0005] To achieve the above object, the present invention provides the following solutions:

[0006] One of the technical solutions of the present invention: A preparation method of an electrocatalyst for acidic oxygen evolution reaction, comprising the following steps:

[0007] In-situ grow transition metal oxide on a conductive substrate to obtain a transition metal oxide support;

[0008] Perform plasma treatment on the transition metal oxide support and then place it in a noble metal salt solution for cation exchange reaction to obtain the electrocatalyst.

[0009] Further, the preparation method of the transition metal oxide support comprises the following steps:

[0010] Place the conductive substrate in an acidic solution of transition metal salt, heat and react to obtain the transition metal oxide support.

[0011] Furthermore, the conductive substrate includes titanium felt, carbon cloth, carbon paper or nickel foam.

[0012] Furthermore, before placing the conductive substrate in the acidic solution of transition metal salt, it further includes a step of pre-treating the conductive substrate, specifically including:

[0013] Pre-treat the conductive substrate in an acidic solution, then wash it several times with water and ethanol, and store it in an ethanol solution for standby.

[0014] The acidic solution is an oxalic acid solution with a concentration of 10wt%; the temperature of the pre-treatment is 80°C and the time is 1h.

[0015] Pre-treating the conductive substrate can remove the oxides and impurities on the surface of the conductive substrate.

[0016] Further, the transition metal salt includes manganese salt or cobalt salt.

[0017] Furthermore, the manganese salt is one of potassium permanganate, manganese sulfate or manganese acetate; the cobalt salt is cobalt nitrate.

[0018] Furthermore, when the transition metal salt is a manganese salt, the composition of the transition metal oxide includes at least one of MnO 2 , Mn 3 O 4 and MnO; when the transition metal salt is a cobalt salt, the composition of the transition metal oxide includes Co 3 O 4 .

[0019] Further, the time of the plasma treatment is 60s - 240min, and the power is 100 - 300W;

[0020] The plasma treatment is argon plasma treatment.

[0021] Performing argon plasma treatment on the transition metal oxide support can obtain a support with a coordination environment rich in oxygen vacancy defects, which is more conducive to the progress of the acidic oxygen evolution reaction.

[0022] Furthermore, the noble metal salt in the noble metal salt solution includes ruthenium salt or iridium salt.

[0023] Even further, the ruthenium salt is ruthenium trichloride; the iridium salt is iridium chloride.

[0024] When the noble metal salt is ruthenium salt, the prepared electrocatalyst is a single-atom Ru-based electrocatalyst; when the noble metal salt is iridium salt, the prepared electrocatalyst is a single-atom Ir-based electrocatalyst.

[0025] Furthermore, the concentration of the noble metal salt solution is 8 - 19 mmol / L.

[0026] Furthermore, the time of the cation exchange reaction is 12 h.

[0027] To introduce single-atom Ru or Ir into the lattice of the transition metal oxide by cation exchange, the metal ions of the selected transition metal oxide must have a similar ionic radius and coordination environment to the noble metal, which is conducive to inducing a strong electronic interaction, thereby realizing a highly active and stable acidic oxygen evolution reaction.

[0028] The present invention prepares a single-atom Ru or Ir-based electrocatalyst by growing a transition metal oxide on a highly hydrophilic and high-attachment-site conductive substrate, followed by in-situ argon plasma treatment and cation exchange reaction.

[0029] The single-atom Ru or Ir-based electrocatalyst prepared by the preparation method of the present invention can be directly used as an electrode without using a binder and slurry coating, avoiding the coverage of catalytic active sites and the adverse effects on conductivity, and simplifying the electrode preparation procedure.

[0030] The transition metal oxide in the single-atom Ru or Ir-based electrocatalyst prepared in this application has a three-dimensional nanoflower structure, with a larger specific surface area, which is conducive to the mass transfer process during catalysis; the introduction of single-atom Ru or Ir can change the lattice structure of the transition metal oxide, improve the conductivity, and optimize the adsorption and desorption process of intermediates. Compared with the traditional adsorbate evolution mechanism, the initial overpotential of the oxidation reaction of the single-atom Ru or Ir-based electrocatalyst is greatly reduced, which makes hydrogen production at the cathode easier, and is accompanied by a new oxygen evolution mechanism (dual active site type LOM mechanism: 1.H 2O molecules adsorb on Ru sites and complete deprotonation to form *OH; 2. *OH undergoes deprotonation to generate *O and *O overflows from Ru sites to Mn sites and finally adsorbs on Mn sites; 3. The surface-adsorbed *O combines with the lattice oxygen of Mn sites to generate O 2 ; 4. The generated O vc is refilled by another H 2 O molecule to regenerate *OH; 5. The deprotonation of *OH generates lattice oxygen to restore the Mn sites to their original state, as Figure 16 shown), and the hydrogen production at the cathode can be greatly improved.

[0031] The second technical solution of the present invention: An electrocatalyst prepared by the above preparation method.

[0032] The third technical solution of the present invention: An application of the above electrocatalyst in water electrolysis.

[0033] The third technical solution of the present invention: An application of the above electrocatalyst in the acidic oxygen evolution reaction.

[0034] The present invention discloses the following technical effects:

[0035] (1) When the electrocatalyst prepared by the present invention is used in the water electrolysis reaction in 0.5M H 2 SO 4 solution, it has an extremely low initial overpotential (187 mV), shows no obvious performance decay during 4500 h of continuous acidic water electrolysis, exhibits high operating stability, and has great application potential in replacing commercial RuO 2 / IrO 2 catalysts and reducing the electrode preparation cost and acidic water electrolysis.

[0036] (2) The present invention first performs argon plasma treatment on the transition metal oxide support to form a main body with a coordination environment rich in oxygen vacancy defects, and then introduces the guest Ru or Ir into the main body to construct a single-atom Ru or Ir-based electrocatalyst with an asymmetric Ru (or Ir)-O-M (transition metal atom) structural unit. The unique coordination environment of this electrocatalyst endows the catalyst with a specific electronic structure, which improves the conductivity of the transition metal oxide after noble metal doping. It also optimizes the adsorption and desorption processes of reaction intermediates, opens up an oxygen evolution path different from the traditional adsorbate evolution mechanism (AEM), activates the oxygen atoms around the transition metal sites, so that not only noble metal atoms can participate in the reaction during the reaction process, but also transition metal atoms can assist the reaction to proceed, thereby achieving the purpose of protecting noble metal atoms from being over-oxidized and realizing ultra-high stability and activity.

[0037] (3) The present invention makes the surface of the transition metal oxide support have the characteristics of highly coordinated unsaturation through the treatment of argon plasma. After noble metal atoms are introduced into the lattice of the transition metal oxide, the original coordination environment can be maintained, and due to the existence of oxygen vacancy defects, the intrinsic activity of the active sites is increased, which is beneficial to the improvement of catalytic activity. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required in the embodiments. Obviously, the drawings in the following description are only some embodiments of the present invention. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative efforts.

[0039] Figure 1 XRD diffraction patterns of MnO 2-x @Ti mesh (300W / 120s) and Ru / MnO 2-x @Ti mesh (300W / 120s);

[0040] Figure 2 Scanning electron microscope images of Ru / MnO 2-x @Ti mesh (300W / 120s) prepared in Example 1;

[0041] Figure 3 O1s XPS spectra of Ru / MnO 2-x @Ti mesh (300W / 120s) prepared in Example 1;

[0042] Figure 4 Aberration-corrected scanning transmission electron microscope images of Ru / MnO 2-x @Ti mesh (300W / 120s) prepared in Example 1;

[0043] Figure 5 LSV curves of Ru / MnO 2-x @Ti mesh (300W / 120s) prepared in Example 1 and Ru / MnO 2 @Ti mesh in 0.5M H 2 SO 4 solution;

[0044] Figure 6 LSV curves of Ru / MnO 2-x @Ti mesh (300W / 120s) prepared in Example 1 and Ru / MnO 2Double-layer capacitance C of @Ti mesh tested at different scan rates between 1.04 V and 1.14 V dl ;

[0045] Figure 7 Ru / MnO prepared in Example 1 2-x @Ti mesh (300 W / 120 s) at a constant current of 10 mA cm -2 Stability curve;

[0046] Figure 8 Ir / MnO prepared in Example 2 2-x @Ti mesh (300 W / 120 s) in 0.5 M H 2 SO 4 LSV curve in the solution;

[0047] Figure 9 Ru / Mn prepared in Example 3 3 O 4 @Ti mesh (300 W / 120 s) in 0.5 M H 2 SO 4 LSV curve in the solution;

[0048] Figure 10 Ir / Mn prepared in Example 4 3 O 4 @Ti mesh (300 W / 120 s) in 0.5 M H 2 SO 4 LSV curve in the solution;

[0049] Figure 11 LSV curve of Ru / MnO@Ti mesh (300 W / 120 s) prepared in Example 5 in 0.5 M H 2 SO 4 solution;

[0050] Figure 12 LSV curve of Ir / MnO@Ti mesh (300 W / 120 s) prepared in Example 6 in 0.5 M H 2 SO 4 solution;

[0051] Figure 13 Ru / Co prepared in Example 7 3 O 4 @Ti mesh (300 W / 120 s) in 0.5 M H 2 SO 4 solution;

[0052] Figure 14Ir / Co prepared for Example 8 3 O 4 @Ti mesh(300W / 120s) in 0.5M H 2 SO 4 LSV curves in solution;

[0053] Figure 15 Ru / MnO prepared for Comparative Example 2 2 @Ti mesh(300W / 120s / O 2 ) and Ru / MnO prepared for Comparative Example 3 2 @Ti mesh(300W / 120s / N 2 ) in 0.5M H 2 SO 4 LSV curves in solution;

[0054] Figure 16 Schematic diagram of oxygen evolution mechanism. Detailed implementation manners

[0055] Now, various exemplary implementation manners of the present invention will be described in detail. This detailed description should not be regarded as a limitation of the present invention, but should be understood as a more detailed description of certain aspects, characteristics and implementation manners of the present invention.

[0056] It should be understood that the terms described in the present invention are only for describing specific implementation manners and are not used to limit the present invention. Additionally, for the numerical ranges in the present invention, it should be understood that each intermediate value between the upper and lower limits of the range is also specifically disclosed. Each intermediate value within any stated value or stated range, as well as each smaller range between any other stated value or intermediate value within the stated range, is also included in the present invention. The upper and lower limits of these smaller ranges can be independently included or excluded from the range.

[0057] Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by those of ordinary skill in the art to which the present invention pertains. Although the present invention only describes preferred methods and materials, any methods and materials similar or equivalent to those described herein can also be used in the implementation or testing of the present invention. All documents mentioned in this specification are incorporated by reference to disclose and describe the methods and / or materials related to the documents. In case of conflict with any incorporated document, the content of this specification shall prevail.

[0058] Without departing from the scope or spirit of the present invention, various improvements and changes can be made to the specific implementation manners of the present invention specification, which are obvious to those skilled in the art. Other implementation manners obtained from the specification of the present invention are obvious to those skilled in the art. The specification and examples of the present invention are only exemplary.

[0059] Regarding the terms "comprising", "including", "having", "containing", etc. used in this text, they are all open-ended terms, meaning including but not limited to.

[0060] It should be noted that the parts not described in detail in the present invention are all conventional operating means in the art and are not the focus of the present invention.

[0061] Example 1

[0062] A preparation method of an electrocatalyst for acidic oxygen evolution reaction:

[0063] (1) Pretreatment of titanium felt: The titanium felt (Ti mesh, with a size of 2 cm × 2 cm) was treated in a 10 wt% oxalic acid solution for 1 h at a temperature of 80 °C (heated by an oil bath). After the treatment, it was taken out, washed several times with deionized water and ethanol, and then placed in an ethanol solution for standby.

[0064] (2) Weigh 1.76 mmol of potassium permanganate and dissolve it in 32 mL of deionized water, stir for 10 min, add 185 μL of concentrated hydrochloric acid dropwise, and continue to stir for 15 min. Transfer it to a 100 mL hydrothermal autoclave, and place the pretreated titanium felt at the bottom of the autoclave. Heat it to 120 °C and maintain it for 12 h. After cooling to room temperature, wash it several times with deionized water and ethanol, and place it in a vacuum drying oven and dry it at 60 °C to obtain a transition metal oxide support (the loading amount of the transition metal oxide is 5 mg / cm 2 ).

[0065] (3) Carry out argon plasma treatment on the transition metal oxide support for 120 s with a power of 300 W to obtain a support with a coordination environment rich in oxygen vacancy defects (i.e., MnO 2-x @Ti mesh(300W / 120s)).

[0066] (4) Place the support with a coordination environment rich in oxygen vacancy defects in 10 mL of a RuCl solution with a concentration of 14.46 mmol / L for a 12 h room-temperature cation exchange reaction. After the reaction, wash it several times with deionized water and ethanol, place it in a vacuum drying oven and dry it at 60 °C to obtain the electrocatalyst Ru / MnO 3 @Ti mesh(300W / 120s). 2-x @Ti mesh(300W / 120s).

[0067] It is known through inductively coupled plasma testing that the content of Ru in the electrocatalyst Ru / MnO 2-x @Ti mesh(300W / 120s) prepared in this example is 2.2 wt.% of the mass of the electrocatalyst.

[0068] The MnO prepared in this example 2-x@Ti mesh(300W / 120s) and Ru / MnO 2-x The XRD diffraction pattern of @Ti mesh(300W / 120s) is shown in Figure 1 ; The Ru / MnO prepared in this example 2-x The scanning electron microscope image of @Ti mesh(300W / 120s) is shown in Figure 2 .

[0069] From Figure 1 it can be seen that the MnO prepared in this example 2-x @Ti mesh(300W / 120s) and Ru / MnO 2-x The carrier in @Timesh(300W / 120s) is MnO 2 ;

[0070] From Figure 2 it can be seen that the Ru / MnO prepared in this example 2-x @Ti mesh(300W / 120s) has a three-dimensional nanoflower morphology, and the nanoflowers are stacked on each other. This morphology of MnO 2 has a larger specific surface area, which is more conducive to the mass transfer process during catalysis.

[0071] The O1s XPS energy spectrum of the Ru / MnO prepared in this example 2-x @Ti mesh(300W / 120s) is shown in Figure 3 , and the aberration-corrected scanning transmission electron microscope image is shown in Figure 4 .

[0072] Figure 3 The M-O in

[0073] Figure 4 is lattice oxygen, Ovc is oxygen vacancy, and Oab is adsorbed oxygen.

[0074] The brighter part in

[0075] Example 2

[0076] (1) Pretreatment of titanium felt: The titanium felt (Ti mesh, with a size of 2 cm × 2 cm) was treated in a 10 wt% oxalic acid solution for 1 h at a temperature of 80 °C (heated by an oil bath), taken out after the treatment, washed several times with deionized water and ethanol, and then placed in an ethanol solution for standby.

[0077] (2) Weigh 1.76 mmol of potassium permanganate and dissolve it in 32 mL of deionized water. Stir for 10 min, then add 185 μL of concentrated hydrochloric acid dropwise and continue stirring for 15 min. Transfer it to a 100 mL hydrothermal reactor, place the pretreated titanium felt at the bottom of the reactor, heat it to 120 °C and maintain for 12 h. After cooling to room temperature, wash it several times with deionized water and ethanol, and place it in a vacuum drying oven to dry at 60 °C to obtain the transition metal oxide support.

[0078] (3) Perform argon plasma treatment on the transition metal oxide support for 120 s at a power of 300 W to obtain a support with a coordination environment rich in oxygen vacancy defects.

[0079] (4) Place the support with a coordination environment rich in oxygen vacancy defects in 10 mL of an iridium chloride solution with a concentration of 14.46 mmol / L for a 12 h cation exchange reaction at room temperature. After the reaction, wash it several times with deionized water and ethanol, and place it in a vacuum drying oven to dry at 60 °C to obtain the electrocatalyst Ir / MnO 2-x @Ti mesh(300W / 120s).

[0080] Example 3

[0081] A preparation method of an electrocatalyst for acidic oxygen evolution reaction:

[0082] (1) Pretreatment of titanium felt: Treat the titanium felt (Ti mesh, size 2 cm × 2 cm) in a 10 wt% oxalic acid solution for 1 h at a temperature of 80 °C (heated by an oil bath). After treatment, take it out, wash it several times with deionized water and ethanol, and then place it in an ethanol solution for standby.

[0083] (2) Weigh 1.76 mmol of manganese acetate and dissolve it in 32 mL of deionized water. Stir for 10 min, then add 185 μL of concentrated hydrochloric acid dropwise and continue stirring for 15 min. Transfer it to a 100 mL hydrothermal reactor, place the pretreated titanium felt at the bottom of the reactor, heat it to 120 °C and maintain for 12 h. After cooling to room temperature, wash it several times with deionized water and ethanol, and place it in a vacuum drying oven to dry at 60 °C to obtain the transition metal oxide support.

[0084] (3) Perform argon plasma treatment on the transition metal oxide support for 120 s at a power of 300 W to obtain a support with a coordination environment rich in oxygen vacancy defects.

[0085] (4) Place the support with a coordination environment rich in oxygen vacancy defects in 10 mL of a RuCl solution with a concentration of 14.46 mmol / L 3A room-temperature cation exchange reaction was carried out in a solution for 12 h. After the reaction, it was washed several times with deionized water and ethanol, placed in a vacuum drying oven, and dried at 60 °C to obtain the electrocatalyst Ru / Mn 3 O 4 @Ti mesh(300W / 120s).

[0086] Example 4

[0087] A preparation method of an electrocatalyst for acidic oxygen evolution reaction:

[0088] (1) Pretreatment of titanium felt: The titanium felt (Ti mesh, size 2 cm × 2 cm) was treated in a 10 wt% oxalic acid solution for 1 h at 80 °C (heated by an oil bath). After treatment, it was taken out, washed several times with deionized water and ethanol, and then placed in an ethanol solution for standby.

[0089] (2) Weigh 1.76 mmol of manganese acetate and dissolve it in 32 mL of deionized water. Stir for 10 min, add 185 μL of concentrated hydrochloric acid, and continue stirring for 15 min. Transfer it to a 100 mL hydrothermal autoclave, and place the pretreated titanium felt at the bottom of the autoclave. Heat it to 120 °C and maintain it for 12 h. After cooling to room temperature, wash it several times with deionized water and ethanol, place it in a vacuum drying oven, and dry it at 60 °C to obtain a transition metal oxide support.

[0090] (3) Perform argon plasma treatment on the transition metal oxide support for 120 s at a power of 300 W to obtain a support with a coordination environment rich in oxygen vacancy defects.

[0091] (4) Place the support with a coordination environment rich in oxygen vacancy defects in 10 mL of an iridium chloride solution with a concentration of 14.46 mmol / L for a room-temperature cation exchange reaction for 12 h. After the reaction, wash it several times with deionized water and ethanol, place it in a vacuum drying oven, and dry it at 60 °C to obtain the electrocatalyst Ir / Mn 3 O 4 @Ti mesh(300W / 120s).

[0092] Example 5

[0093] A preparation method of an electrocatalyst for acidic oxygen evolution reaction:

[0094] (1) Pretreatment of titanium felt: The titanium felt (Ti mesh, size 2 cm × 2 cm) was treated in a 10 wt% oxalic acid solution for 1 h at 80 °C (heated by an oil bath). After treatment, it was taken out, washed several times with deionized water and ethanol, and then placed in an ethanol solution for standby.

[0095] (2) Weigh 1.76 mmol of manganese sulfate and dissolve it in 32 mL of deionized water. Stir for 10 min, then add 185 μL of concentrated hydrochloric acid dropwise and continue stirring for 15 min. Transfer it to a 100 mL hydrothermal reactor, place the pretreated titanium felt at the bottom of the reactor, heat it to 120 °C and maintain for 12 h. After cooling to room temperature, wash it several times with deionized water and ethanol, and place it in a vacuum drying oven to dry at 60 °C to obtain a transition metal oxide support.

[0096] (3) Perform argon plasma treatment on the transition metal oxide support for 120 s at a power of 300 W to obtain a support with a coordination environment rich in oxygen vacancy defects.

[0097] (4) Place the support with a coordination environment rich in oxygen vacancy defects in 10 mL of a RuCl 3 solution with a concentration of 14.46 mmol / L for a 12 h room temperature cation exchange reaction. After the reaction is completed, wash it several times with deionized water and ethanol, and place it in a vacuum drying oven to dry at 60 °C to obtain the electrocatalyst Ru / MnO@Ti mesh(300W / 120s).

[0098] Example 6

[0099] A preparation method of an electrocatalyst for acidic oxygen evolution reaction:

[0100] (1) Pretreatment of titanium felt: Treat the titanium felt (Ti mesh, size 2 cm × 2 cm) in a 10 wt% oxalic acid solution for 1 h at a temperature of 80 °C (heated by an oil bath). After treatment, take it out, wash it several times with deionized water and ethanol, and then place it in an ethanol solution for standby.

[0101] (2) Weigh 1.76 mmol of manganese sulfate and dissolve it in 32 mL of deionized water. Stir for 10 min, then add 185 μL of concentrated hydrochloric acid dropwise and continue stirring for 15 min. Transfer it to a 100 mL hydrothermal reactor, place the pretreated titanium felt at the bottom of the reactor, heat it to 120 °C and maintain for 12 h. After cooling to room temperature, wash it several times with deionized water and ethanol, and place it in a vacuum drying oven to dry at 60 °C to obtain a transition metal oxide support.

[0102] (3) Perform argon plasma treatment on the transition metal oxide support for 120 s at a power of 300 W to obtain a support with a coordination environment rich in oxygen vacancy defects.

[0103] (4) Place the support with a coordination environment rich in oxygen vacancy defects in 10 mL of an iridium chloride solution with a concentration of 14.46 mmol / L for a room-temperature cation exchange reaction for 12 h. After the reaction, wash it several times with deionized water and ethanol, place it in a vacuum drying oven, and dry it at 60 °C to obtain the electrocatalyst Ir / MnO@Ti mesh(300W / 120s).

[0104] Example 7

[0105] A preparation method of an electrocatalyst for acidic oxygen evolution reaction:

[0106] (1) Pretreatment of titanium felt: Treat the titanium felt (Ti mesh, size 2 cm × 2 cm) in a 10 wt% oxalic acid solution for 1 h at a temperature of 80 °C (heated by an oil bath). After the treatment, take it out, wash it several times with deionized water and ethanol, and then place it in an ethanol solution for standby.

[0107] (2) Weigh 1.76 mmol of cobalt nitrate and dissolve it in 32 mL of deionized water, stir for 10 min, add 185 μL of concentrated hydrochloric acid, and continue stirring for 15 min. Transfer it to a 100 mL hydrothermal autoclave, and place the pretreated titanium felt at the bottom of the autoclave. Heat it to 120 °C and maintain it for 12 h. After cooling to room temperature, wash it several times with deionized water and ethanol, place it in a vacuum drying oven, and dry it at 60 °C to obtain the transition metal oxide support.

[0108] (3) Perform argon plasma treatment on the transition metal oxide support for 120 s with a power of 300 W to obtain a support with a coordination environment rich in oxygen vacancy defects.

[0109] (4) Place the support with a coordination environment rich in oxygen vacancy defects in 10 mL of a RuCl 3 solution for a room-temperature cation exchange reaction for 12 h. After the reaction, wash it several times with deionized water and ethanol, place it in a vacuum drying oven, and dry it at 60 °C to obtain the electrocatalyst Ru / Co 3 O 4 @Ti mesh(300W / 120s).

[0110] Example 8

[0111] A preparation method of an electrocatalyst for acidic oxygen evolution reaction:

[0112] (1) Pretreatment of titanium felt: Treat the titanium felt (Ti mesh, size 2 cm × 2 cm) in a 10 wt% oxalic acid solution for 1 h at a temperature of 80 °C (heated by an oil bath). After the treatment, take it out, wash it several times with deionized water and ethanol, and then place it in an ethanol solution for standby.

[0113] (2) Weigh 1.76 mmol of cobalt nitrate and dissolve it in 32 mL of deionized water. Stir for 10 min, add 185 μL of concentrated hydrochloric acid dropwise, and continue stirring for 15 min. Transfer it to a 100 mL hydrothermal reactor, place the pretreated titanium felt at the bottom of the reactor, heat it to 120 °C and maintain for 12 h. After cooling to room temperature, wash it several times with deionized water and ethanol, place it in a vacuum drying oven, and dry it at 60 °C to obtain a transition metal oxide support.

[0114] (3) Perform argon plasma treatment on the transition metal oxide support for 120 s with a power of 300 W to obtain a support with a coordination environment rich in oxygen vacancy defects.

[0115] (4) Place the support with a coordination environment rich in oxygen vacancy defects in 10 mL of an iridium chloride solution with a concentration of 14.46 mmol / L for a 12 h room-temperature cation exchange reaction. After the reaction is completed, wash it several times with deionized water and ethanol, place it in a vacuum drying oven, and dry it at 60 °C to obtain the electrocatalyst Ir / Co 3 O 4 @Ti mesh(300W / 120s).

[0116] Comparative Example 1

[0117] A preparation method of an electrocatalyst for the oxygen evolution reaction in acidic medium:

[0118] (1) Pretreatment of titanium felt: Treat the titanium felt (Ti mesh, size 2 cm × 2 cm) in a 10 wt% oxalic acid solution for 1 h at 80 °C (heated by an oil bath). After treatment, take it out, wash it several times with deionized water and ethanol, and place it in an ethanol solution for standby.

[0119] (2) Weigh 1.76 mmol of potassium permanganate and dissolve it in 32 mL of deionized water. Stir for 10 min, add 185 μL of concentrated hydrochloric acid dropwise, and continue stirring for 15 min. Transfer it to a 100 mL hydrothermal reactor, place the pretreated titanium felt at the bottom of the reactor, heat it to 120 °C and maintain for 12 h. After cooling to room temperature, wash it several times with deionized water and ethanol, place it in a vacuum drying oven, and dry it at 60 °C to obtain a transition metal oxide support.

[0120] (3) Place the transition metal oxide support in 10 mL of a RuCl 3 solution for a 12 h room-temperature cation exchange reaction. After the reaction is completed, wash it several times with deionized water and ethanol, place it in a vacuum drying oven, and dry it at 60 °C to obtain the electrocatalyst Ru / MnO 2 @Ti mesh.

[0121] Comparative Example 2

[0122] A preparation method of an electrocatalyst for the acidic oxygen evolution reaction:

[0123] (1) Pretreatment of titanium felt: The titanium felt (Ti mesh, size 2 cm × 2 cm) was treated in a 10 wt% oxalic acid solution for 1 h at a temperature of 80 °C (heated by an oil bath). After the treatment, it was taken out, washed several times with deionized water and ethanol, and then placed in an ethanol solution for standby.

[0124] (2) Weigh 1.76 mmol of potassium permanganate and dissolve it in 32 mL of deionized water. Stir for 10 min, add 185 μL of concentrated hydrochloric acid dropwise, and continue to stir for 15 min. Transfer it to a 100 mL hydrothermal reactor, and place the pretreated titanium felt at the bottom of the reactor. Heat it to 120 °C and maintain for 12 h. After cooling to room temperature, wash it several times with deionized water and ethanol, and place it in a vacuum drying oven and dry it at 60 °C to obtain a transition metal oxide support.

[0125] (3) The transition metal oxide support was treated with oxygen plasma for 120 s at a power of 300 W to obtain a support.

[0126] (4) The support was placed in a 10 mL solution of 14.46 mmol / L RuCl 3 for a 12 h room-temperature cation exchange reaction. After the reaction, it was washed several times with deionized water and ethanol, placed in a vacuum drying oven, and dried at 60 °C to obtain the electrocatalyst Ru / MnO 2 @Ti mesh (300 W / 120 s / O 2 ).

[0127] Comparative Example 3

[0128] A preparation method of an electrocatalyst for the acidic oxygen evolution reaction:

[0129] (1) Pretreatment of titanium felt: The titanium felt (Ti mesh, size 2 cm × 2 cm) was treated in a 10 wt% oxalic acid solution for 1 h at a temperature of 80 °C (heated by an oil bath). After the treatment, it was taken out, washed several times with deionized water and ethanol, and then placed in an ethanol solution for standby.

[0130] (2) Weigh 1.76 mmol of potassium permanganate and dissolve it in 32 mL of deionized water. Stir for 10 min, add 185 μL of concentrated hydrochloric acid dropwise, and continue to stir for 15 min. Transfer it to a 100 mL hydrothermal reactor, and place the pretreated titanium felt at the bottom of the reactor. Heat it to 120 °C and maintain for 12 h. After cooling to room temperature, wash it several times with deionized water and ethanol, and place it in a vacuum drying oven and dry it at 60 °C to obtain a transition metal oxide support.

[0131] (3) The transition metal oxide support is treated with nitrogen plasma for 120 s at a power of 300 W to obtain the support.

[0132] (4) The support is placed in a 10 mL solution of RuCl with a concentration of 14.46 mmol / L for a 12-h room-temperature cation exchange reaction. After the reaction, it is washed several times with deionized water and ethanol, placed in a vacuum drying oven, and dried at 60 °C to obtain Ru / MnO 3 @Ti mesh (300 W / 120 s / N 2 )。 2 )。

[0133] Effect Example 1

[0134] Using an electrochemical workstation and a three-electrode system, the single-atom Ru-based electrocatalyst prepared in Example 1 or Comparative Example 1 is used as the working electrode, a platinum plate electrode is used as the counter electrode, and a silver / silver chloride electrode is used as the reference electrode. The electrolyte is 0.5 M H 2 SO 4 , and electrochemical tests are carried out.

[0135] The electrochemical tests mainly include: the linear sweep voltammetry (LSV) curve of the acidic OER of the prepared single-atom Ru-based electrocatalyst electrode; the CV curves of each electrode tested at different scan rates at 1.04 - 1.14 V to calculate the double-layer capacitance (C dl ), and estimate the electrochemically active specific surface area (ECSA); the constant current stability curve measured at 10 mA cm -2 .

[0136] (1) The LSV curves of Ru / MnO 2-x @Ti mesh (300 W / 120 s) prepared in Example 1 and Ru / MnO 2 @Timesh in 0.5 M H 2 SO 4 solution are shown in Figure 5 .

[0137] It can be seen from Figure 5 that without argon plasma treatment, the electrocatalytic OER activity of the sample electrode is average. In contrast, for the electrode treated with argon plasma, the potential is significantly reduced.

[0138] (2) The double-layer capacitance C of Ru / MnO 2-x @Ti mesh (300 W / 120 s) prepared in Example 1 and Ru / MnO 2 @Timesh tested at different scan rates at 1.04 - 1.14 V respectivelydl (The CV curves were tested, and the double-layer capacitance C of different electrodes was calculated according to the CV curves dl ) See Figure 6 .

[0139] It can be seen from Figure 6 that the single-atom Ru-based electrocatalyst electrode (Ru / MnO 2-x @Ti mesh(300W / 120s)) prepared in Example 1 has a good C dl value, indicating that the single-atom Ru-based electrocatalyst prepared by the preparation method of the present invention has higher reaction activity.

[0140] (3) The constant current stability curve of Ru / MnO 2-x @Ti mesh(300W / 120s) prepared in Example 1 in 0.5M H 2 SO 4 solution at 10mA cm -2 is shown in Figure 7 .

[0141] It can be seen from Figure 7 that the single-atom Ru-based electrocatalyst electrode (Ru / MnO 2-x @Ti mesh(300W / 120s)) prepared in Example 1 has no obvious change in potential after electrolysis at a constant current density of 10mA cm -2 for 4500h, indicating that the single-atom Ru-based electrocatalyst electrode prepared in Example 1 has good stability.

[0142] (4) The LSV curve of Ir / MnO 2-x @Ti mesh(300W / 120s) prepared in Example 2 in 0.5M H 2 SO 4 solution is shown in Figure 8 ; The LSV curve of Ru / Mn 3 O 4 @Ti mesh(300W / 120s) prepared in Example 3 in 0.5M H 2 SO 4 solution is shown in Figure 9 ; The LSV curve of Ir / Mn 3 O 4 @Ti mesh(300W / 120s) prepared in Example 4 in 0.5M H 2 SO 4 solution is shown in Figure 10 ; The LSV curve of Ru / MnO@Ti mesh(300W / 120s) prepared in Example 5 in 0.5M H 2 SO 4The LSV curves in the solution are shown in Figure 11 ; The LSV curve of Ir / MnO@Ti mesh (300W / 120s) prepared in Example 6 in 0.5M H 2 SO 4 solution is shown in Figure 12 ; The LSV curve of Ru / Co 3 O 4 @Ti mesh (300W / 120s) in 0.5M H 2 SO 4 solution is shown in Figure 13 ; The LSV curve of Ir / Co 3 O 4 @Ti mesh (300W / 120s) in 0.5M H 2 SO 4 solution is shown in Figure 14 .

[0143] It can be seen from Figures 8 - 14 that the electrocatalysts prepared in the present invention all have relatively good reaction activities, and the activity of single-atom Ru is slightly higher than that of single-atom Ir.

[0144] Effect Example 2

[0145] Using an electrochemical workstation and a three-electrode system, the single-atom Ru-based electrocatalyst electrode prepared in Comparative Example 2 or Comparative Example 3 was used as the working electrode, a platinum sheet electrode was used as the counter electrode, and a silver / silver chloride electrode was used as the reference electrode. The electrolyte was 0.5M H 2 SO 4 , and electrochemical tests were carried out.

[0146] The electrochemical tests mainly included: the linear sweep voltammetry curve (LSV) of the acidic OER of the prepared single-atom Ru-based electrocatalyst electrode, and the results are shown in Figure 15 .

[0147] It can be seen from Figure 5 and Figure 15 that the single-atom Ru-based electrocatalyst electrode prepared from the transition metal oxide electrode treated with nitrogen plasma has a certain degree of enhancement in activity compared to the electrode not treated with plasma, but the oxygen deficiency is just the opposite. It shows that the electrode of the transition metal oxide (i.e., the carrier with a coordination environment rich in oxygen vacancy defects) creating a highly coordinatively unsaturated coordination environment by argon plasma has a positive effect on the performance.

[0148] The initial overpotentials of the electrocatalysts prepared in the examples and comparative examples are shown in Table 1.

[0149] Table 1 Initial overpotential

[0150]

[0151] The embodiments described above are only descriptions of the preferred embodiments of the present invention, and do not limit the scope of the present invention. Without departing from the design spirit of the present invention, various deformations and improvements made by those of ordinary skill in the art to the technical solutions of the present invention shall fall within the protection scope determined by the claims of the present invention.

Claims

1. A method for preparing an electrocatalyst for acidic oxygen evolution reaction, characterized in that: The following steps are involved: In-situ growing of a transition metal oxide on a conductive substrate to obtain a transition metal oxide support; The transition metal oxide carrier is subjected to plasma treatment and then placed in a noble metal salt solution for a cation exchange reaction to obtain the electrocatalyst.

2. The preparation method according to claim 1, characterized in that: The preparation method of the transition metal oxide carrier comprises the following steps: The conductive substrate is placed in an acidic solution of a transition metal salt and heated for reaction to obtain the transition metal oxide support.

3. The preparation method according to claim 2, characterized in that: The transition metal salt includes a manganese salt or a cobalt salt.

4. The preparation method according to claim 1, characterized in that: The plasma treatment time is 60s to 240min, and the power is 100 to 300W; And / or, the plasma treatment is argon plasma treatment.

5. The preparation method according to claim 1, characterized in that: The noble metal salt in the noble metal salt solution includes ruthenium salt or iridium salt.

6. The preparation method according to claim 1, characterized in that: The concentration of the noble metal salt solution is 8-19 mmol / L.

7. The preparation method according to claim 1, characterized in that: The cation exchange reaction time is 12h.

8. An electrocatalyst prepared by the preparation method according to any one of claims 1 to 7.

9. Use of the electrocatalyst according to claim 8 in electrolysis of water.

10. Use of the electrocatalyst according to claim 8 in an acidic oxygen evolution reaction.

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