Cathode hydrogen evolution catalyst for all-pH electrolysis water and preparation and application thereof

Abstract

The application discloses a cathode hydrogen evolution catalyst for full-pH electrolysis water and preparation and application thereof, and belongs to the technical field of hydrogen production by electrolysis of water. First, nano WO3 is deposited on a foam copper substrate through a hydrothermal reaction, and then the foam copper substrate is immersed in a metal source solution to load metal species, and then heat treatment is carried out in an H2 atmosphere to realize reduction of metal active sites and hydrogenation of the WO3 substrate, so that the proton blocking type metal Ru / Pt / Ir NPs is loaded on the non-proton blocking type metal oxide H x The composite structure catalyst on the WO3 carrier can serve as a "hydrogen bank" to continuously provide protons to the high-activity interface metal active site, and then realize excellent HER performance through a Tafel process, and reduce the dependence of the reaction on the acid-base environment of the electrolyte; when the carrier morphology is a nano needle shape, the composite catalyst Ru-H x The WO3NN exhibits low overpotential and high stability under an industrial current density in the HER of full-pH electrolysis water.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of hydrogen production by electrolysis of water, and particularly relates to a cathode hydrogen evolution catalyst for electrolysis of water at all pH values and a preparation and application thereof. BACKGROUND

[0002] The large consumption of fossil resources leads to excessive emission of carbon dioxide, which in turn triggers serious climate problems. Developing effective technologies that can help achieve "carbon neutrality" is an inevitable choice for sustainable development.

[0003] Hydrogen (H2) is the best energy carrier to replace fossil fuels due to its high energy density and zero carbon emission. There are many methods for producing hydrogen, among which electrolysis of water is an effective way to produce high-purity hydrogen in an efficient and green manner. The cathodic hydrogen evolution reaction (HER) consists of the formation of adsorbed hydrogen (H*) (Volmer step) and coupling (Heyrovsky / Tafel step). To improve the reaction efficiency, a suitable electrocatalyst can be selected to reduce the energy barrier of each step.

[0004] Electrocatalytic water splitting for hydrogen production can be carried out in acidic, neutral and alkaline environments. Among them, the hydrogen evolution reaction (HER) process in neutral / alkaline medium requires an additional water dissociation step to provide protons, and the kinetics of water dissociation is slow, resulting in a low hydrogen coverage on the catalyst surface and a significantly slower overall kinetics than acidic HER. In particular, in the process of neutral water and direct seawater electrolysis, significant local pH changes often occur on the catalyst surface. For example, in a strongly buffered electrolyte, a pH change of more than 2 units can occur even at a moderate current density of-30 mA cm -2 This pH fluctuation will become more pronounced at amperage current density, which will greatly affect the performance of the hydrogen evolution reaction in neutral medium. In particular, for proton-blocking metal catalysts such as ruthenium (Ru), platinum (Pt) and iridium (Ir), proton reduction and H* coupling can only occur on the catalyst surface, and the HER mechanism that changes with the local pH determines that such materials are difficult to achieve efficient hydrogen evolution at all pH values. In order to be able to respond to the influence of changes in acid-base environment on HER activity, it is of great significance to develop new high-performance HER catalysts that can be well applied to different pH conditions to ensure the stability and high efficiency of the catalyst during long-term operation and to improve the efficiency of the process of electrolysis of water for hydrogen production.

[0005] "Reversible hydrogen spillover in Ru-WO 3-xenhances hydrogen evolutionactivity in neutral pH water splitting[J].Nature Communications volume 13,Article number:5382(2022).” One kind of composite material catalyst which can effectively improve the hydrogen evolution reaction (HER) activity in neutral medium is disclosed in the article, specifically, it loads ruthenium nanoparticles (Ru NPs) on oxygen-deficient tungsten trioxide (WO 3-x ) and the oxygen-deficient WO 3-x is proved to have the ability to store protons, and the stored protons can be transferred to the surface of RuNPs at the cathode potential, thereby significantly increasing the hydrogen coverage on the surface of RuNPs, so that the determining step of hydrogen evolution reaction on the surface of Ru changes from water dissociation to hydrogen recombination, and the hydrogen evolution reaction (HER) activity is increased by 24.0 times compared with the commercial Ru / C electrocatalyst.

[0006] However, the Ru-WO 3-x composite catalyst provided in the prior art mainly solves the problem of low HER activity in neutral environment, and it cannot be directly known whether it can play the same or similar effect in alkaline environment, nor can it be known by the disclosed content without doubt. And the carrier of the composite material catalyst disclosed in the document is oxygen-deficient WO 3-x , which has proton storage ability, but needs to realize hydrogen adsorption and storage before the subsequent transfer and recombination process can be completed, which will affect the efficiency of the initial reaction to some extent, and further considering the problem that the water dissociation kinetics is slow in alkaline environment, the initial hydrogen storage effect of oxygen-deficient WO 3-x will be obviously affected in the corresponding environment, and further affect the HER activity in the corresponding environment.

[0007] Based on the above problems, the assumption is proposed after in-depth thinking: if hydrogen can be pre-embedded into the crystal lattice of non-protic blocking transition metal oxide (such as WO3, MoO3, etc.) as a catalyst carrier to form lattice hydrogen, act as a "hydrogen reservoir", and then be compounded with proton blocking metal catalyst (ruthenium (Ru), platinum (Pt), iridium (Ir) and the like), a high-efficiency hydrogen circulation transport channel can be directly established between the two, and the lattice hydrogen in the "hydrogen reservoir" can be directly transported to the metal catalyst surface to occur hydrogen evolution process in the reaction starting stage, a fast lattice H migration path from the non-protic blocking carrier to the proton blocking metal catalyst is established, which helps the catalytic reaction to proceed quickly without obstacles, and the consumed lattice H in the reaction process is expected to be spontaneously supplemented through H adsorption (acidic) or H2O dissociation (alkaline). If this process can be successfully realized, the dependence of the catalytic reaction on the pH value of the electrolyte can be effectively reduced, and the goal of high HER reaction activity under full pH conditions can be finally achieved.

[0008] However, it should be pointed out that the prerequisite for realizing the above assumption is to further explore the preparation process of the composite catalyst to successfully introduce lattice hydrogen into the crystal lattice of the non-protic blocking transition metal oxide, in addition, the person skilled in the art knows that the morphology of the catalyst carrier will also have a significant impact on the catalytic activity of the composite catalyst, and it is also necessary to further regulate the morphology of the carrier to maximize the HER catalytic performance and reaction stability while embedding lattice hydrogen into the carrier crystal lattice. SUMMARY

[0009] In view of the above problems, the present application aims to provide a cathode hydrogen evolution catalyst for full pH electrolytic water and discloses a preparation method thereof. The catalyst takes foamed copper as a substrate, grows non-protic blocking tungsten oxide (H x WO3) rich in lattice hydrogen as a carrier on the substrate, and loads proton blocking metal active sites (preferably Ru NPs) on the carrier. The morphology and size of the carrier can be regulated, and the density of the active sites can be regulated. The optimized composite catalyst exhibits excellent catalytic activity for the cathode hydrogen evolution reaction (HER) of electrolytic water under full pH conditions, and can reach industrial current density at ultra-low overpotential.

[0010] To achieve the above purpose, the technical scheme adopted by the present application is as follows: a preparation method of a cathode hydrogen evolution catalyst for full pH electrolytic water, comprising the following steps:

[0011] 1) pretreating the foamed copper substrate;

[0012] 2) dissolving tungstate in water, adjusting the pH of the solution to 0.8-2, stirring, adding oxalic acid and cationic sulfate, and stirring uniformly to obtain a precursor solution;

[0013] 3) Put the pretreated foam copper substrate into the precursor solution, and perform hydrothermal reaction, take out the sample after the reaction, and wash and dry to obtain the foam copper deposited with nano WO3;

[0014] 4) Prepare a metal source solution;

[0015] 5) Put the foam copper deposited with nano WO3 into the metal source solution for 50-70 min, and take out, wash and dry;

[0016] 6) Put the sample obtained in the above step into a tube furnace, and perform calcination in a reducing atmosphere containing H2 to perform thermal hydrogenation of the WO3 substrate and reduction of the metal, so as to form a proton-blocking metal and aprotic-blocking carrier composite structure, that is, a final product catalyst.

[0017] Further, in step 2), the tungstate is any one of sodium tungstate, ammonium metatungstate and potassium tungstate, and preferably sodium tungstate; the cationic sulfate is one or more of lithium sulfate, sodium sulfate, potassium sulfate and ammonium sulfate; the metal source solution is a ruthenium source solution, a platinum source solution or an iridium source solution, the solvent of the metal source solution is 0.1M HCl, and the concentration of the metal source material in the solution is 2-20 g / L.

[0018] The molar ratio of tungstate, oxalate and cation of cationic sulfate is 2-5:6-10:8-15.

[0019] Further, in step 3), the temperature for performing hydrothermal reaction is 160-200°C, and preferably 180°C, and the hydrothermal reaction time is 6-36h, and preferably 16h.

[0020] Further, in step 6), the calcination temperature is 300-500°C, and preferably 400°C, and the hydrogen content in the reducing atmosphere is 10%-100%, and the rest is argon, and preferably the reducing atmosphere is pure hydrogen.

[0021] Further, in step 4), the metal source solution is preferably a ruthenium source; the ruthenium source is any one or more of anhydrous ruthenium chloride, hydrated ruthenium chloride, potassium hexachlororuthenate (III), and potassium hexachlororuthenate (IV), and preferably hydrated ruthenium chloride; the platinum source is any one of anhydrous platinum chloride, hydrated platinum chloride, chloroplatinic acid, and potassium hexachloroplatinate, and preferably chloroplatinic acid; and the iridium source is any one of anhydrous iridium chloride (III or IV), hydrated iridium chloride (III or IV), chloroiridic acid, and potassium hexachloroiridate (III or IV).

[0022] The cathode hydrogen evolution catalyst for full-pH electrolytic water prepared based on the above method is a metal-oxide composite structure catalytic material, which is specifically a non-protic-blocking metal oxide H xWO3 as a carrier, the carrier loaded with ruthenium, platinum or iridium nanoparticles as proton blocking type metal active sites, the composite structure grown on a foam copper conductive substrate.

[0023] The reason why the present application selects foam copper as the conductive substrate is that Cu can be used as an excellent and inexpensive metal for dissociating H2 at high temperature, and can form a thermal H overflow phenomenon with WO3 which can receive H atoms, i.e. Cu sites dissociate H2, and the active H after dissociation can be transferred to WO3 to form stable lattice hydrogen, thereby realizing the pre-insertion of lattice H. Subsequently, protons are continuously provided to the high-activity interface metal active site.

[0024] The present application introduces lattice H atoms into WO3 NP S by thermal hydrogenation, so that it becomes H x rich WO3, and the design of the composite structure enables the establishment of a rapid lattice H migration path from the non-proton blocking carrier (H x WO3) to the proton blocking metal catalyst (Ru) through H transfer between O sites during the catalytic process, which reduces the dependence on the pH value of the electrolyte, and H x consumed in the WO3 carrier can be spontaneously supplemented through H adsorption (acidic) or H2O dissociation (alkaline), realizing the cycle of lattice hydrogen.

[0025] Further, the H x WO3 carrier has a morphology of nanoneedle, nanowire or nanorod, the H x The morphology of the WO3 carrier is controlled by adjusting the cation composition and concentration of the hydrothermal process; the size of the metal active site is 2-10 nm;

[0026] When the H x WO3 carrier has a morphology of nanoneedle, the diameter of the tip of the nanoneedle is 15-25 nm, the diameter of the tail end is 80-120 nm, and the length is 1-4 μm;

[0027] When the H x WO3 carrier has a morphology of nanowire, the diameter of the nanowire is 70-90 nm;

[0028] When the H x WO3 carrier has a morphology of nanorod, the diameter of the nanorod is 180-220 nm.

[0029] As a preferred embodiment, the H x WO3 carrier has a morphology of nanoneedle, and the metal active site loaded on the carrier is a ruthenium nanoparticle.

[0030] The cathode hydrogen evolution catalyst can be used for catalysis of cathode hydrogen evolution reaction of water electrolysis under full pH conditions, can reach industrial current density (@1Acm -2 ) at ultra-low overpotential (acid: 129mV, neutral: 219mV and alkaline: 142mV), and has high stability (500h+@1Acm -2 ).

[0031] The beneficial effects of the present application are:

[0032] 1. The present application combines hydrothermal reaction, noble metal impregnation and thermal insertion hydrogen reduction to prepare a metal-oxide composite structure catalyst which can be used for full pH hydrogen evolution, which takes the lattice hydrogen-rich aprotic blocking type metal oxide H x WO3 as the carrier, and the carrier is loaded with proton blocking type metal active sites (Ru / Pt / Ir NPs), and the composite structure is grown on a foam copper conductive substrate, and the lattice hydrogen-rich carrier can act as a "hydrogen bank" to continuously provide protons to the high-activity interface metal active site, so that excellent HER performance is achieved through the Tafel process;

[0033] 2. The composite structure catalyst prepared in the present application realizes efficient lattice hydrogen circulation in the process of water electrolysis by pre-introducing lattice H atoms into the carrier, establishes a fast lattice H migration path from the aprotic blocking carrier (H x WO3) to the proton blocking metal catalyst (Ru / Pt / Ir) through H transfer between O sites, which can improve the reaction kinetics and reduce the dependence of the reaction on the acid-base environment of the electrolyte; and the consumed lattice H x WO3 in the carrier can be spontaneously supplemented through H adsorption (acidic) or H2O dissociation (alkaline);

[0034] 3. By adjusting the cation composition and concentration of the hydrothermal process, the morphology and size of the H x WO3 carrier can be controlled. The carrier morphology can be nanoneedle-shaped, nanorod-shaped or nanowire-shaped. It has been verified that when the carrier morphology is nanoneedle-shaped (the tip diameter is 15-25nm, the tail diameter is 80-120nm, and the length reaches several microns), and the loaded metal active site is Ru NPs, the composite catalyst Ru-H x WO3 NN exhibits extremely excellent HER catalytic activity when used for water electrolysis under full pH conditions, and can reach industrial current density at ultra-low overpotential;

[0035] 4. The metal-oxide composite structure catalyst disclosed in the present application can realize efficient and stable fast hydrogen evolution reaction under full pH conditions, and Ru-H xWO3 NN can exhibit excellent HER (acid: 129 mV, neutral: 219 mV, basic: 142 mV) catalytic performance under alkaline, neutral, and acidic electrolyte conditions; in addition, it also exhibits a high exchange current density (1 A cm -2 exhibits ultra-high stability under industrial current density (500 h + @ 1 A cm -2 ). BRIEF DESCRIPTION OF DRAWINGS

[0036] Figure 1 Neutron diagram a is the composite catalyst Ru-H x WO3 NN-1 prepared in Example 1, sub-diagram b is an enlarged view of part A in sub-diagram a, i.e. a partial enlarged schematic diagram of nano-WO3, and sub-diagram c is an enlarged view of part B in sub-diagram a, i.e. a partial enlarged schematic diagram of Ru-H x WO3 NN-1 prepared in Example 1, sub-diagram b is an enlarged view of part A in sub-diagram a, i.e. a partial enlarged schematic diagram of nano-WO3, and sub-diagram c is an enlarged view of part B in sub-diagram a, i.e. a partial enlarged schematic diagram of Ru-H

[0037] Figure 2 Neutron diagram a is the composite catalyst Ru-H x WO3 NN-1 prepared in Example 1, sub-diagram b is an enlarged view of part A in sub-diagram a, i.e. a partial enlarged schematic diagram of nano-WO3, and sub-diagram c is an enlarged view of part B in sub-diagram a, i.e. a partial enlarged schematic diagram of Ru-H

[0038] Figure 3 Neutron diagram a is the composite catalyst Ru-H x WO3 NN-1 prepared in Example 1, sub-diagram b is an enlarged view of part A in sub-diagram a, i.e. a partial enlarged schematic diagram of nano-WO3, and sub-diagram c is an enlarged view of part B in sub-diagram a, i.e. a partial enlarged schematic diagram of Ru-H

[0039] Figure 4 Neutron diagram a is the composite catalyst Ru-H x WO3 NN-1 prepared in Example 1, sub-diagram b is an enlarged view of part A in sub-diagram a, i.e. a partial enlarged schematic diagram of nano-WO3, and sub-diagram c is an enlarged view of part B in sub-diagram a, i.e. a partial enlarged schematic diagram of Ru-H x WO3 NN-1 prepared in Example 1, sub-diagram b is an enlarged view of part A in sub-diagram a, i.e. a partial enlarged schematic diagram of nano-WO3, and sub-diagram c is an enlarged view of part B in sub-diagram a, i.e. a partial enlarged schematic diagram of Ru-H x WO3 NN-1 prepared in Example 1, sub-diagram b is an enlarged view of part A in sub-diagram a, i.e. a partial enlarged schematic diagram of nano-WO3, and sub-diagram c is an enlarged view of part B in sub-diagram a, i.e. a partial enlarged schematic diagram of Ru-H x WO3 NN-1 prepared in Example 1, sub-diagram b is an enlarged view of part A in sub-diagram a, i.e. a partial enlarged schematic diagram of nano-WO3, and sub-diagram c is an enlarged view of part B in sub-diagram a, i.e. a partial enlarged schematic diagram of Ru-H

[0040] Figure 5 Neutron diagram a is the composite catalyst Ru-H x WO3 NN-1 prepared in Example 1, sub-diagram b is an enlarged view of part A in sub-diagram a, i.e. a partial enlarged schematic diagram of nano-WO3, and sub-diagram c is an enlarged view of part B in sub-diagram a, i.e. a partial enlarged schematic diagram of Ru-H x WO3 NN-1 prepared in Example 1, sub-diagram b is an enlarged view of part A in sub-diagram a, i.e. a partial enlarged schematic diagram of nano-WO3, and sub-diagram c is an enlarged view of part B in sub-diagram a, i.e. a partial enlarged schematic diagram of Ru-H x WO3 NN-1 prepared in Example 1, sub-diagram b is an enlarged view of part A in sub-diagram a, i.e. a partial enlarged schematic diagram of nano-WO3, and sub-diagram c is an enlarged view of part B in sub-diagram a, i.e. a partial enlarged schematic diagram of Ru-H xFigure 1. HER catalytic performance of WO3NN-1 and corresponding comparative catalysts in 1 M KOH medium; sub-figure d is a comparison of the overpotential and Tafel slope of different catalysts; sub-figure e is a comparison of the Ru-H x Figure 2. Catalytic stability test of WO3NN-1. DETAILED DESCRIPTION

[0041] In order to enable those skilled in the art to better understand the technical solutions of the present application, the technical solutions of the present application are further described below in combination with the drawings and examples.

[0042] Example 1

[0043] The present embodiment discloses a preparation method of a cathode hydrogen evolution catalyst for full-pH electrolytic water. The prepared catalyst is a composite structure catalyst formed after loading Ru nanoparticles (RuNPs) of a proton blocking type metal active site on a non-proton blocking type tungsten oxide (H x WO3) carrier, which is grown on a foam copper conductive substrate. The synthesis process refers to Figure 1 , and the specific preparation steps are as follows:

[0044] 1) Pretreatment of the substrate: cut the foam copper (CF) to a suitable size (2 cm x 4 cm), first ultrasonic treatment in 1 M dilute hydrochloric acid for 20 min to remove the surface oxide layer, then ultrasonic treatment in acetone for 30 min to remove the surface organic dirt, ultrasonic treatment in ultrapure water for 30 min to wash away the excess acetone, and finally store the foam copper in ethanol for standby.

[0045] 2) Preparation of nano-WO3: weigh 0.9900 g of sodium tungstate dihydrate, add 30 mL of ultrapure water, then add appropriate amount of hydrochloric acid to adjust the pH to about 1.0, then stir for 20 min, then add 1.0580 g of oxalic acid dihydrate, 1.5857 g of ammonium sulfate and 1.7040 g of sodium sulfate, and stir for another 20 min, then transfer it to a polytetrafluoroethylene reaction kettle liner (volume: 50 mL), put the foam copper substrate treated in step 1) into the solution, and place it in a stainless steel high-pressure reaction kettle, and heat it at 180°C for 16 h, then cool it to room temperature, take out the foam copper on which nano-tungsten oxide has grown, wash it with ultrapure water and ethanol several times, and dry it at 75°C overnight;

[0046] 3) Preparation of Ru solution: weigh 250 mg of RuCl3xH2O, dissolve it in 100 mL of 0.1 M HCl to prevent hydrolysis of Ru, and stir for 30 min to mix evenly;

[0047] 4) Impregnation with Ru: Cut the copper foam loaded with nano WO3 obtained in step 2) into 1cm×2cm size, place it in 10mL of Ru solution prepared in step 3), impregnate for 60min, take it out and wash it with ultrapure water and ethanol respectively, and dry it at 75℃ overnight.

[0048] 5) Thermal hydrogenation of the support and reduction of the metal: The dried sample prepared in step 4) is placed in a tube furnace and heated at 100 mL / min. -1 A high-purity H2 atmosphere (hydrogen volume percentage > 99.9%) was introduced at a flow rate of 5℃ / min. -1 The temperature was increased to 400℃ at a certain rate, and thermal reduction was carried out for 2 hours. After cooling to room temperature, the sample was removed. This yielded a composite catalyst with metallic Ru supported on a lattice-hydrogen-rich tungsten oxide support.

[0049] Figure 2 , Figure 3 These are scanning electron microscope (SEM) and transmission electron microscope (TEM) images of the composite catalyst prepared in this embodiment, respectively. Figure 3 Neutron graph b clearly shows that nanoparticles are loaded on the support surface and bound together. Figures 2-3 It can be seen that the tungsten oxide (H2O) rich in lattice hydrogen prepared in this embodiment is... x The morphology of WO3 is that of nanoneedles, with a tip diameter of approximately 20 nm, a tail diameter of approximately 100 nm, and a length of several micrometers; loaded on H x The Ru nanoparticles (Ru NPs) on the WO3 surface serve as metal active sites, with a size of approximately 2-10 nm. Based on the composite catalyst prepared in this embodiment, the support morphology is nanoneedle-like (NN), therefore the composite material prepared in this embodiment is denoted as Ru-H. x WO3 NN-1, Ru-H on substrate x The loading capacity of WO3NN-1 is approximately 8.0 mg / cm³. -2 .

[0050] Figure 4 Neutron diagrams a and b represent Ru-H... x High-resolution transmission electron microscopy (TEM) and aberration-corrected electron microscopy (AEM) images of WO3 NN-1 show that Ru nanoparticles are loaded onto H. x On the WO3 carrier; now let's look at Ru-H. x XRD pattern of WO3 NN-1 ( Figure 4 The positive shift of the peak at 23.2° in neutron plot c) confirms the insertion of H; Figure 4 Neutron diagram d is Ru-H x The Raman spectrum of WO3 NN-1, as seen in the image, is at 1580 cm⁻¹. -1 The peak at that location corresponds to the WO-H peak, confirming the presence of H in the lattice.

[0051] Comparative Example 1

[0052] The difference between this comparative example and Example 1 is that the non-protic blocking type tungsten oxide (H x WO3) carrier is not loaded with protic blocking type metal active sites Ru nanoparticles (RuNPs), and the specific preparation process is as follows:

[0053] 1) Pretreatment of foam copper (CF) substrate: the process is the same as step 1) of Example 1.

[0054] 2) Preparation of nano-WO3: the process is the same as step 2) of Example 1;

[0055] 3) Thermal hydrogenation of the carrier: the dried sample prepared in step 2) is placed in a tube furnace, and high-purity H2 atmosphere is introduced at a flow rate of 100 mL min -1 -1, and heated to 400°C at a rate of 5°C min -1 -1, and heated to 400°C at a rate of 5°C min x -1, and heated to 400°C at a rate of 5°C min

[0056] Comparative Example 2

[0057] The difference between this comparative example and Example 1 is that the carrier tungsten oxide is not subjected to thermal hydrogenation, i.e. the protons are not pre-embedded into the WO3 lattice to form lattice hydrogen, and the specific preparation process is as follows:

[0058] 1)-4): the process is the same as steps 1)-4) of Example 1.

[0059] 5) Reduction of only metal: the dried sample prepared in step 4) is placed in a 20 mg mL -1 -1 solution, treated for 20 min, and the treated sample is washed several times with ultrapure water and ethanol, and then dried again for 10 h. A composite structure catalyst is obtained, in which metal Ru is loaded on the needle-shaped tungsten oxide carrier, and is recorded as Ru-WO3NN.

[0060] HER performance test: three-electrode system: Ru-H x WO3 NN-1 is cut into a size of 1 cm x 1 cm and used as the working electrode, the electrode is clamped on a platinum electrode clamp, and the electrolyte is selected from 0.5 M H2SO4, 1 M PBS and 1 M KOH solution; Hg / Hg2SO4 electrode, saturated calomel electrode (SCE), Hg / HgO electrode as reference electrode in acidic, neutral and alkaline conditions, and graphite rod as counter electrode. HER test: under the conditions of normal temperature and pressure, 20 mL min -1The N2 flow was maintained for 20 min to remove other gases in the solution, and then cyclic voltammetry scanning (-0.2-0.2 V (vs. RHE), scan rate 20 mV / s) was performed for 30 cycles to activate the catalyst, followed by LSV test to determine the HER overpotential.

[0061] Comparative catalysts Ru-WO3NN, H x The HER performance test process of WO3NN, Pt / C, and Ru / C was the same as above.

[0062] Figure 5 Neutron graphs a-c respectively show the HER catalytic performance of Ru-H x WO3 NN-1 (labeled as Ru-H x WO3 NN) and the corresponding comparative catalysts in 0.5M H2SO4, 1M PBS, and 1M KOH medium environments. The vertical coordinate represents the current density, and the horizontal coordinate represents the voltage compared with the reversible hydrogen electrode. As can be seen from graphs a-c, under the above reaction conditions, Ru-H x WO3 NN-1 can achieve a current density of 10 mA cm -2 at overpotentials of 12 mV, 28 mV, and 14 mV, respectively, in 0.5M H2SO4, 1M PBS, and 1M KOH medium environments, and can achieve an industrial current density of 1 A cm -2 at overpotentials of 129 mV, 219 mV, and 142 mV, respectively. Graph d is the overpotential and Tafel slope comparison chart of the catalysts Ru-H x WO3 NN-1 (labeled as Ru-H x WO3 NN), Ru-WO3NN, Pt / C, and Ru / C. As can be seen from the graph, the catalytic performance of Ru-H x WO3 NN-1 prepared in Example 1 is more superior. Graph e is the chronoamperogram of Ru-H x WO3 NN-1 at a current density of 1 A cm -2 . As can be seen from the graph, the catalyst Ru-H x WO3 NN-1 prepared in Example 1 can stably catalyze for more than 500 h at a current density of 1 A cm -2 , and has high stability.

[0063] Example 2

[0064] The difference between this example and Example 1 is only in step 2). In this example, the amount of cationic sulfate used in the hydrothermal preparation of nano-WO3 is changed, and the type and amount of tungstate are replaced. The specific process of step 2) is as follows:

[0065] 2) Preparation of nano-WO3: 0.8900 g of ammonium metatungstate was weighed into 30 mL of ultrapure water, and then an appropriate amount of hydrochloric acid was added to adjust the pH to about 1.0, followed by stirring for 20 min, then 1.0580 g of oxalic acid dihydrate, 1.0575 g of ammonium sulfate and 2.2720 g of sodium sulfate were added, and stirred for another 20 min. It was transferred to a polytetrafluoroethylene reactor liner (volume: 50 mL), and the foam copper substrate treated in step 1) was placed in the solution, and placed in a stainless steel high-pressure reactor, and hydrothermal reaction was carried out at 180°C for 16 h. After cooling to room temperature, the foam copper on which nano-tungsten oxide was grown was taken out, washed several times with ultrapure water and ethanol, and dried at 75°C overnight.

[0066] The support of the composite catalyst prepared in this example was also nano-needle-shaped (NN), and the obtained catalyst was recorded as Ru-H x WO3 NN-2, Ru-H on substrate x The loading of WO3 NN-2 was about 12.5 mg cm -2 .

[0067] HER test: test method as above, Ru-H x WO3 NN-2 can achieve a current density of 10 mA cm -2 at overpotential of 21 mV, 42 mV and 27 mV, respectively, in 0.5 M H2SO4, 1 M PBS, 1 M KOH medium, and can achieve an industrial current density of 1 A cm -2 at overpotential of 179 mV, 299 mV and 202 mV, respectively, and can stably catalyze for more than 400 h under the condition of a current density of 1 A cm -2 .

[0068] Example 3

[0069] The difference between this example and Example 1 is only that the cationic sulfate used in the preparation of nano-WO3 by hydrothermal reaction is only ammonium sulfate, and the other steps remain unchanged. The specific process of step 2) is as follows:

[0070] 2) Preparation of nano-WO3: 0.8900 g of ammonium metatungstate was weighed into 30 mL of ultrapure water, and then an appropriate amount of hydrochloric acid was added to adjust the pH to about 1.0, followed by stirring for 20 min, then 1.0580 g of oxalic acid dihydrate, 1.0575 g of ammonium sulfate and 2.2720 g of sodium sulfate were added, and stirred for another 20 min. It was transferred to a polytetrafluoroethylene reactor liner (volume: 50 mL), and the foam copper substrate treated in step 1) was placed in the solution, and placed in a stainless steel high-pressure reactor, and hydrothermal reaction was carried out at 180°C for 16 h. After cooling to room temperature, the foam copper on which nano-tungsten oxide was grown was taken out, washed several times with ultrapure water and ethanol, and dried at 75°C overnight.

[0071] The carrier of the composite catalyst prepared in this example is nanowire (NW) with a diameter of about 80 nm, and the obtained catalyst is recorded as Ru-H x WO3 NW-1, Ru-H on substrate x The loading of WO3 NW-1 is about 8.0 mg cm-2. -2 .

[0072] HER test: the test method is the same as above, Ru-H x WO3 NW-1 can achieve a current density of 10 mA cm-2 at an overpotential of 41 mV, 72 mV and 39 mV in 0.5 M H2SO4, 1 M PBS and 1 M KOH medium, respectively, and can be stably catalyzed for more than 200 h at a current density of 10 A cm-2. -2 -2

[0073] Example 4

[0074] The difference between this example and Example 1 is only that the cationic sulfate used in the preparation of nanometer WO3 by hydrothermal reaction is only sodium sulfate, and the other steps remain unchanged. The specific process of step 2) is as follows:

[0075] 2) Preparation of nanometer WO3: weigh 0.9900 g of sodium tungstate dihydrate, add 30 mL of ultrapure water, then add appropriate amount of hydrochloric acid to adjust the pH to about 1.0, then stir for 20 min, then add 1.0580 g of oxalic acid dihydrate and 1.7040 g of sodium sulfate, and stir for another 20 min. Transfer it to a polytetrafluoroethylene reactor liner (volume: 50 mL), put the foam copper substrate treated in step 1) into the solution, and place it in a stainless steel high-pressure reactor. Hydrothermal reaction at 180℃ for 16 h. After cooling to room temperature, take out the foam copper on which nanometer tungsten oxide has grown, wash it with ultrapure water and ethanol several times, and dry it at 75℃ overnight.

[0076] The carrier of the composite catalyst prepared in this example is nanorod (NR) with a diameter of about 200 nm, and the obtained catalyst is recorded as Ru-H x WO3 NR-1, Ru-H on substrate x The loading of WO3 NR-1 is about 8.0 mg cm-2. -2 .

[0077] HER test: the test method is the same as above, Ru-H x WO3 NR-1 can achieve a current density of 10 mA cm-2 at an overpotential of 72 mV, 109 mV and 77 mV in 0.5 M H2SO4, 1 M PBS and 1 M KOH medium, respectively, and can be stably catalyzed for more than 200 h at a current density of 10 A cm-2. -2 -2 ​​​current density of 1 A cm-2for more than 200 h.

[0078] Example 5

[0079] The difference between this example and Example 1 is only that the type and amount of the ruthenium source is changed in the preparation of the Ru solution in step 3), and the other steps remain unchanged. The specific process of step 3) is as follows:

[0080] 3) Preparation of Ru solution: 520 mg of K2RuCl6 was weighed and dissolved in 100 mL of 0.1M HCl to prevent hydrolysis of Ru, and stirred for 30 min to mix evenly.

[0081] The support morphology of the composite catalyst prepared in this example is nanoneedle (NN), and the obtained catalyst is recorded as Ru-2-H x WO3 NN, Ru-2-H on substrate x The loading of WO3 NN is about 8.1 mg cm-2. -2 .

[0082] HER test: the test method is the same as above, Ru-2-H x WO3 NN can achieve a current density of 10 mA cm-2at overpotential of 19 mV, 36 mV and 25 mV, respectively, in 0.5M H2SO4, 1M PBS and 1M KOH medium, and a current density of 1 mA cm-2at overpotential of 151 mV, 271 mV and 182 mV, respectively, and can be stably catalyzed at a current density of 1 A cm-2for more than 200 h. -2 . -2 -2 .

[0083] Example 6

[0084] The difference between this example and Example 1 is only that the type and amount of the ruthenium source is changed in the preparation of the Ru solution in step 3), and the other steps remain unchanged. The specific process of step 3) is as follows:

[0085] 3) Preparation of Ru solution: 520 mg of K2RuCl6 was weighed and dissolved in 100 mL of 0.1M HCl to prevent hydrolysis of Ru, and stirred for 30 min to mix evenly.

[0086] The support morphology of the composite catalyst prepared in this example is nanoneedle (NN), and the obtained catalyst is recorded as Ru-2-H x WO3 NN, Ru-3-H on substrate x The loading of WO3 NN is about 8.2 mg cm-2. -2 .

[0087] HER test: the test method is the same as above, Ru-3-H​x WO3 NN can achieve a current density of 10 mA cm-2at overpotential of 22 mV, 32 mV, 27 mV, respectively, and a current density of 1 mA cm-2at overpotential of 144 mV, 250 mV, 177 mV, respectively, in 0.5 M H2SO4, 1 M PBS, 1 M KOH medium environment, and can stably catalyze for more than 200 h under the condition of a current density of 1 A cm-2. -2 -2 -2

[0088] Example 7

[0089] The difference between this example and Example 1 is that the ruthenium source is replaced by an iridium source when preparing the metal active site solution in step 3), and the subsequent impregnation solution is changed accordingly. The specific process of steps 3) to 4) is as follows:

[0090] 3) Preparation of Ir solution: 250 mg of IrCl3was weighed and dissolved in 100 mL of 0.1 M HCl to prevent hydrolysis of Ir, and stirred for 30 min to mix uniformly.

[0091] 4) Impregnation of Ir: The nano-WO3-loaded foam copper prepared in step 2) was cut into a size of 1 cm x 2 cm, and placed in 10 mL of the Ir solution prepared in step 3) for impregnation for 60 min. After taking out, it was washed with ultrapure water and ethanol respectively, and dried at 75°C overnight.

[0092] The support morphology of the composite catalyst prepared in this example is nano needle (NN), and the obtained catalyst is recorded as Ir-HxWO3 NN. x WO3 NN, and the loading of Ir-HxWO3 NN on the substrate is about 8.0 mg cm-2. x -2 .

[0093] HER test: the test method is the same as above. Ir-HxWO3 NN can achieve a current density of 10 mA cm-2at overpotential of 50 mV, 62 mV, 52 mV, respectively, and a current density of 1 mA cm-2at overpotential of 279 mV, 395 mV, 327 mV, respectively, in 0.5 M H2SO4, 1 M PBS, 1 M KOH medium environment, and can stably catalyze for more than 24 h under the condition of a current density of 1 A cm-2. -2 -2 -2

[0094] Example 8

[0095] The difference between this example and Example 1 is that the ruthenium source is replaced by a platinum source when preparing the metal active site solution in step 3), and the subsequent impregnation solution is changed accordingly. The specific process of steps 3) to 4) is as follows:​​​​​​​

[0096] 3) Prepare Pt solution: Weigh 300 mg H2PtCl6, dissolve it in 100 mL 0.1 M HCl, and stir for 30 min to mix evenly.

[0097] 4) Pt impregnation: Cut the copper foam loaded with nano-WO3 obtained in step 2) into 1cm×2cm size, place it in 10mL of Pt solution prepared in step 3), impregnate for 60min, take it out and wash it with ultrapure water and ethanol respectively, and dry it at 75℃ overnight.

[0098] The composite catalyst prepared in this embodiment has a support morphology of nanoneedle-like (NN) and the resulting catalyst is denoted as Pt-H. x WO3 NN, Pt-H on substrate x The loading capacity of WO3 NN is approximately 8.0 mg / cm³. -2 .

[0099] HER testing: The testing method is the same as above, Pt-H x WO3 NN can achieve 10 mA cm⁻¹ at overpotentials of 18 mV, 39 mV, and 29 mV in 0.5 M H₂SO₄, 1 M PBS, and 1 M KOH media, respectively. -2 The current density, and the achievement of 1 mA cm⁻¹ at overpotentials of 152 mV, 265 mV, and 187 mV respectively. -2 Industrial-grade current density, and at 1Acm -2 It can stably catalyze for more than 24 hours under the current density conditions.

[0100] The test data from Examples 1 to 8 show that the metal-oxide composite catalysts prepared in the examples of this application can all be used for water electrolysis under all pH conditions, with reduced dependence on acid and alkaline environments and excellent HER activity.

[0101] Furthermore, the composition of the proton-blocking metal active sites loaded on the support, and the composition of the lattice-rich hydrogen-rich non-proton-blocking tungsten oxide (H2O) x The morphology of the WO3 support directly affects the activity of the composite catalyst in the cathodic hydrogen evolution reaction (HER) under all pH conditions. The preferred composition of the proton-blocking metal active sites is ruthenium sodium nanoparticles with a size of 2–10 nm. x The preferred morphology of the WO3 support is nanoneedle-shaped with a tip of about 20 nm, a tail of about 100 nm, and a length of several micrometers. Under these conditions, the composite catalyst exhibits low overpotential and high stability at industrial-grade current density during the cathodic hydrogen evolution reaction (HER) of water electrolysis at full pH.

[0102] The above shows and describes the basic principles, main features and advantages of the present application. However, the above is only a specific embodiment of the present application, and the technical features of the present application are not limited thereto. Any other embodiments obtained by those skilled in the art without departing from the technical solutions of the present application should be covered in the scope of the present application.

Claims

1. A method for preparing a cathode hydrogen evolution catalyst for all-pH electrolysis water, characterized by, The method comprises the following steps: 1) pretreating the foamed copper substrate; 2) dissolving a tungstate in water, adjusting the pH of the solution to 0.8-2, stirring, adding oxalic acid and a cationic sulfate, and stirring uniformly to obtain a precursor solution; 3) placing the pretreated foamed copper substrate into the precursor solution to perform a hydrothermal reaction, taking out the sample after the reaction, and washing and drying to obtain the foamed copper with deposited nano-WO3; 4) preparing a metal source solution, which is a ruthenium source solution, a platinum source solution or an iridium source solution; 5) placing the foamed copper with deposited nano-WO3 into the metal source solution for 50-70 min, and taking out the sample after washing and drying; 6) placing the sample obtained in the above step into a tube furnace to perform calcination in a reducing atmosphere containing H2, to perform thermal hydrogenation of the WO3 substrate and reduction of the metal, and to form a metal-oxide composite structure, i.e. the final product catalyst.

2. The method for preparing a cathode hydrogen evolution catalyst for all-pH electrolyzed water according to claim 1, characterized by, In step 2), the tungstate is any one of sodium tungstate, ammonium metatungstate or potassium tungstate; the cationic sulfate is one or more selected from lithium sulfate, sodium sulfate, potassium sulfate and ammonium sulfate; the solvent of the metal source solution is 0.1M HCl, and the concentration of the metal source material in the solution is 2-20g / L.

3. The method for preparing a cathode hydrogen evolution catalyst for all-pH electrolyzed water according to claim 1, characterized by, The molar ratio of tungstate, oxalate and the cation of the cationic sulfate is 2-5:6-10:8-15.

4. The method for preparing a cathode hydrogen evolution catalyst for all-pH electrolyzed water according to claim 1, characterized by, In step 3), the temperature for performing the hydrothermal reaction is 160-200℃, and the hydrothermal reaction time is 6-36h.

5. The method for preparing a cathode hydrogen evolution catalyst for all-pH electrolyzed water according to claim 1, characterized by, In step 6), the calcination temperature is 300-500℃, the content of hydrogen in the reducing atmosphere is 10%-100%, and the rest is argon.

6. The method for preparing a cathode hydrogen evolution catalyst for all-pH electrolyzed water according to claim 2, characterized by, In step 4), the ruthenium source is any one or more of anhydrous ruthenium chloride, hydrated ruthenium chloride, potassium trivalent hexachlororuthenate and potassium tetravalent hexachlororuthenate; the platinum source is any one selected from anhydrous platinum chloride, hydrated platinum chloride, chloroplatinic acid and potassium hexachloroplatinate; and the iridium source is any one selected from anhydrous iridium chloride, hydrated iridium chloride, chloroiridic acid and potassium trivalent or tetravalent hexachloroiridate.

7. A cathode hydrogen evolution catalyst for all-pH electrolysis of water, characterized by, It is prepared according to the preparation method of any one of claims 1-6, and the catalyst is a metal-oxide composite structure catalytic material, specifically a non-protic blocking type metal oxide H x WO3 as the carrier, and ruthenium, platinum or iridium nanoparticles as the proton blocking type metal active site are loaded on the carrier, and the composite structure is grown on a foamed copper conductive substrate.

8. The cathode hydrogen evolution catalyst for all-pH electrolytic water according to claim 7, characterized by, H x The morphology of the WO3 support is nanoneedle-like, nanowire-like or nanorod-like,H x The morphology of the WO3 support is controlled by adjusting the cation composition and concentration of the hydrothermal process; the size of the metal active sites is 2-10 nm; H x When the morphology of the WO3 carrier is nanoneedle-shaped, the tip diameter of the nanoneedle is 15-25 nm, the tail diameter is 80-120 nm, and the length is 1-4 μm. H x When the morphology of the WO3 carrier is nanowire, the diameter of the nanowire is 70-90 nm. H x When the morphology of the WO3 support is nanorod, the diameter of the nanorod is 180-220 nm.

9. The cathode hydrogen evolution catalyst for all-pH electrolytic water according to claim 8, characterized by, H x The morphology of the WO3 support is nanoneedle-like, and the metal active sites supported on the support are ruthenium nanoparticles.

10. Use of the cathodic hydrogen evolution catalyst for all-pH electrolytic water according to claim 7 in electrolytic water, characterized in that, The cathode hydrogen evolution catalyst can be used for cathode hydrogen evolution reaction under full pH conditions, can reach an industrial-grade current density at an ultra-low overpotential, and has high stability.

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