Cathode hydrogen evolution catalyst for all-pH electrolyzed water as well as preparation and application of cathode hydrogen evolution catalyst

Abstract

The invention discloses a cathode hydrogen evolution catalyst for full-pH electrolyzed water as well as preparation and application of the cathode hydrogen evolution catalyst, and belongs to the technical field of hydrogen production by electrolyzed water. The preparation method comprises the following steps: depositing nano WO3 on a foamy copper substrate through a hydrothermal reaction, immersing the foamy copper substrate into a metal source solution to load metal species, and carrying out heat treatment in an H2 atmosphere to realize reduction of metal active sites and hydrogenation of a WO3 substrate, according to the present invention, the Ru / Pt / Ir NPs is loaded on the non-proton blocking type metal oxide HxWO3 carrier rich in lattice hydrogen to form the composite structure catalyst with the proton blocking type metal Ru / Pt / Ir NPs loaded on the non-proton blocking type metal oxide HxWO3 carrier rich in lattice hydrogen, the carrier rich in lattice hydrogen can serve as the hydrogen library to continuously provide protons to the high-activity interface metal active site so as to achieve the excellent HER performance through the Tafel process, and the dependence of the reaction on the electrolyte acid-base environment is reduced; when the morphology of the carrier is in a nanoneedle shape, the composite catalyst Ru-HxWO3NN shows low overpotential and high stability under industrial-grade current density in HER of full-pH electrolyzed water.

Description

Technical Field

[0001] The present invention belongs to the technical field of hydrogen production by electrolyzing water, and particularly relates to a cathode hydrogen evolution catalyst for all-pH electrolyzed water, and its preparation and application. Background Art

[0002] The massive consumption of fossil resources has led to excessive carbon dioxide emissions, which in turn has triggered serious climate problems. Developing effective technologies that can help achieve "carbon neutrality" has become an inevitable choice for sustainable development.

[0003] Hydrogen (H 2 ) has become the best energy carrier to replace fossil fuels due to its high energy density and carbon-free emission advantages. There are many methods for producing hydrogen. Among them, hydrogen production by electrolyzing water is an efficient and green effective way to produce high-purity hydrogen. The cathode hydrogen evolution reaction (HER) consists of the formation (Volmer step) and coupling (Heyrovsky / Tafel step) of adsorbed hydrogen (H*). To improve the reaction efficiency, a suitable electrocatalyst can be selected to lower 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 media requires an additional water dissociation step to provide protons, and the kinetic process of water dissociation is slow, resulting in a low hydrogen coverage on the catalyst surface, and the overall reaction kinetics is significantly slower than that of acidic HER. Especially in the processes of neutral water and direct seawater electrolysis, significant local pH value changes often occur on the catalyst surface. For example, in a strong buffer electrolyte, even at a moderate current density of -30 mA cm -2 , a pH value change of more than 2 units can occur. This pH fluctuation will become more obvious at an ampere-level current density, which will greatly affect the hydrogen evolution reaction performance in neutral media. Especially for proton-blocking metal catalysts such as ruthenium (Ru), platinum (Pt), and iridium (Ir), proton reduction and the coupling of H* can only occur on the catalyst surface, and the HER mechanism that changes with the local pH value determines that it is difficult for such materials to achieve efficient hydrogen evolution that is universal for all pH values. In order to be able to freely cope with the influence of acid-base environment changes on HER activity, developing new high-performance HER catalysts that are well suitable for different pH conditions to ensure the stability and efficiency of the catalyst during long-term operation is of great significance for long-term improving the efficiency of the hydrogen production process by electrolyzing water.

[0005] "Reversible hydrogen spillover in Ru-WO 3-xenhances hydrogen evolution activity in neutral pH water splitting[J].Nature Communications volume 13,Article number:5382(2022).” discloses a composite catalyst that can effectively improve the activity of the hydrogen evolution reaction (HER) in neutral media. Specifically, it loads ruthenium nanoparticles (Ru NPs) onto oxygen-deficient tungsten trioxide (WO 3-x ) and the oxygen-deficient WO 3-x has been proven to have the ability to store protons. The stored protons can be transferred to the surface of Ru NPs at the cathode potential, thus significantly increasing the hydrogen coverage on the surface of Ru NPs, making the rate-determining step of the hydrogen evolution reaction on the Ru surface change from water dissociation to hydrogen recombination. Compared with the commercial ruthenium / carbon (Ru / C) electrocatalyst, its hydrogen evolution reaction (HER) activity is increased by 24.0 times.

[0006] However, the Ru-WO 3-x composite catalyst provided in the prior art mainly solves the problem of low HER activity in a neutral environment. As for whether it can achieve the same or similar effect in an alkaline environment, it cannot be directly known, nor can it be inferred without doubt from the disclosed content. Moreover, the carrier used in the composite catalyst disclosed in this document is oxygen-deficient WO 3-x , which, although having the ability to store protons, needs to first achieve hydrogen adsorption and storage during the working process before the subsequent transfer and recombination process can be completed. This will to a certain extent affect the efficiency of the initial reaction. Further considering the slow dissociation kinetics of water in an alkaline environment, the initial hydrogen storage effect of oxygen-deficient WO 3-x will be significantly affected in the corresponding environment, thereby affecting the HER activity in the corresponding environment.

[0007] After in-depth consideration of the above problems, a hypothesis is proposed: If hydrogen can be pre-embedded into the lattice of a non-proton-blocking transition metal oxide (such as WO 3 , MoO 3 , etc.) serving as a catalytic carrier to form lattice hydrogen, acting as a "hydrogen reservoir", and then it is combined with a proton-blocking metal catalyst (ruthenium (Ru), platinum (Pt), iridium (Ir), etc.), an efficient hydrogen circulation and transport channel can be directly established between the two. At the initial stage of the reaction, the lattice hydrogen in the "hydrogen reservoir" can be continuously transported to the surface of the metal catalyst for hydrogen evolution, establishing a fast lattice H migration path from the non-proton-blocking carrier to the proton-blocking metal catalyst to help the catalytic reaction proceed quickly without obstacles. As for the lattice H consumed during the reaction process, it is expected to be replenished through H adsorption (acidic) or H 2O dissociation (alkalinity) achieves spontaneous replenishment. If this process can be successfully achieved, it will effectively reduce the dependence of the catalytic reaction on the pH value of the electrolyte and ultimately achieve the goal of high HER reaction activity under all pH conditions.

[0008] However, one thing that needs to be made clear is that the premise for realizing the above concept is that the preparation process of the composite catalyst still needs to be further explored in order to successfully introduce lattice hydrogen into the lattice of the non-proton-blocking transition metal oxide. In addition, those skilled in the art know that the morphology of the catalytic carrier will also have a significant effect on the catalytic activity of the composite catalyst. While realizing the embedding of lattice hydrogen into the carrier lattice, it is also necessary to further regulate the morphology of the carrier in order to maximize the HER catalytic performance and reaction stability. Summary of the invention

[0009] In view of the above problems, the present invention aims to provide a cathode hydrogen evolution catalyst for full pH water electrolysis and discloses a preparation method thereof. The catalyst uses foam copper as a substrate and grows a non-proton blocking tungsten oxide (H2O) rich in lattice hydrogen on the substrate. x WO 3 ) is used as a carrier, and proton-blocking metal active sites (preferably Ru NPs) are loaded on the carrier. The carrier morphology and size are controllable, and the density of active sites is controllable. The optimized composite catalyst exhibits excellent catalytic activity for the cathode hydrogen evolution reaction (HER) of water electrolysis under all pH conditions, and can reach industrial-grade current density at ultra-low overpotential.

[0010] In order to achieve the above object, the technical solution adopted by the present invention is as follows: A method for preparing a cathode hydrogen evolution catalyst for full pH water electrolysis, comprising the following steps:

[0011] 1) Pretreatment of the foam copper substrate;

[0012] 2) Dissolve tungstate in water, adjust the solution pH to 0.8-2, stir, add oxalic acid and cationic sulfate, stir evenly to obtain a precursor solution;

[0013] 3) Place the pretreated copper foam substrate into the precursor solution for hydrothermal reaction, take out the sample after the reaction, wash and dry it, and obtain the deposited nano-WO 3 Copper foam;

[0014] 4) preparing a metal source solution;

[0015] 5) Deposit nano WO 3 The foamed copper is immersed in the metal source solution for 50 to 70 minutes, taken out, washed and dried;

[0016] 6) Place the sample obtained in the previous step in a tube furnace and heat it in a 2 WO was calcined in a reducing atmosphere3 Thermal hydrogenation of the substrate and reduction of the metal form a proton-blocking metal and a non-proton-blocking carrier composite structure, thus obtaining the final product catalyst.

[0017] Further, in step 2), the tungstate is any one of sodium tungstate, ammonium metatungstate, and potassium tungstate, preferably sodium tungstate; the cationic sulfate is selected from 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 the cation in the cationic sulfate is 2-5:6-10:8-15.

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

[0020] Further, in step 6), the calcination temperature is 300-500 °C, preferably 400 °C, the hydrogen content in the reducing atmosphere is 10% - 100%, and the rest is argon. 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 ruthenium(III) chloride anhydrous, ruthenium(III) chloride hydrate, potassium hexachlororuthenate(III), and potassium hexachlororuthenate(IV), preferably ruthenium(III) chloride hydrate; the platinum source is selected from any one of platinum(IV) chloride anhydrous, platinum(IV) chloride hydrate, chloroplatinic acid, and potassium hexachloroplatinate, preferably chloroplatinic acid; the iridium source is selected from any one of iridium(III or IV) chloride anhydrous, iridium(III or IV) chloride hydrate, chloroiridic acid, and potassium hexachloroiridate(III or IV).

[0022] The cathode hydrogen evolution catalyst for all-pH electrolyzed water prepared based on the above method is a catalytic material with a metal-oxide composite structure. Specifically, it is a non-proton-blocking metal oxide H x WO 3 as the carrier, and ruthenium, platinum, or iridium nanoparticles are loaded on the carrier as proton-blocking metal active sites, and the composite structure grows on the foam copper conductive substrate.

[0023] The reason for choosing foam copper as the conductive substrate in this application is that Cu can be an excellent and inexpensive metal for dissociating H 2 at high temperatures, and it can form a thermal H spillover phenomenon with the oxide WO 3 that can accept H atoms, that is, it realizes the dissociation of H at the Cu site 2 , and the dissociated active H can be transferred to WO 3Stable lattice hydrogen is formed thereon, thereby realizing the pre-insertion of lattice H. Subsequently, it is used to continuously provide protons to the highly active interfacial metal active sites.

[0024] In this application, through thermal hydrogenation, WO 3 NP S After introducing lattice H atoms into it, it becomes H rich in lattice hydrogen x WO 3 , the design of the composite structure enables the establishment of a rapid lattice H migration path from the non-proton-blocking carrier (H x WO 3 ) to the proton-blocking metal catalyst (Ru) through the H transition between O sites during the catalytic process. This process reduces the dependence on the pH value of the electrolyte, and the lattice H consumed in the H x WO 3 carrier can be spontaneously replenished through H adsorption (acidic) or H 2 O dissociation (basic), realizing the lattice hydrogen cycle.

[0025] Furthermore, the morphology of the H x WO 3 carrier is nanoneedle-shaped, nanowire-shaped or nanorod-shaped. The morphology of the H x WO 3 carrier is regulated by adjusting the cation composition and concentration of the hydrothermal process; the size of the metal active sites is 2 - 10 nm;

[0026] When the morphology of the H x WO 3 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;

[0027] When the morphology of the H x WO 3 carrier is nanowire-shaped, the diameter of the nanowire is 70 - 90 nm;

[0028] When the morphology of the H x WO 3 carrier is nanorod-shaped, the diameter of the nanorod is 180 - 220 nm.

[0029] Preferably, the morphology of the H x WO 3 carrier is nanoneedle-shaped, and the metal active sites supported on the carrier are ruthenium nanoparticles.

[0030] The above-mentioned cathode hydrogen evolution catalyst can be used for catalyzing the cathode hydrogen evolution reaction of water electrolysis under all pH conditions, and can reach the industrial current density (@1Acm -2), and has high stability (500h+@1Acm -2 ).

[0031] The beneficial effects of the present invention are as follows:

[0032] 1. This application combines hydrothermal reaction, noble metal impregnation and thermal hydrogen insertion reduction methods to prepare a metal-oxide composite structure catalyst for hydrogen evolution at all pH values. It uses a non-proton-blocking metal oxide H x WO 3 as a carrier, and proton-blocking metal active sites (Ru / Pt / Ir NPs) are loaded on the carrier. The composite structure grows on a copper foam conductive substrate. The carrier rich in lattice hydrogen can act as a "hydrogen reservoir" and continuously provide protons to the highly active interfacial metal active sites, and then achieve excellent HER performance through the Tafel process;

[0033] 2. The composite structure catalyst prepared in this application realizes efficient lattice hydrogen circulation during the electrolysis of water by pre-introducing lattice H atoms into the carrier. Through the H transition between O sites, a rapid lattice H migration path from the non-proton-blocking carrier (H x WO 3 ) to the proton-blocking metal catalyst (Ru / Pt / Ir) is established, 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 in the H x WO 3 carrier can be spontaneously replenished through H adsorption (acidic) or H 2 O dissociation (alkaline);

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

[0035] 4. The metal-oxide composite structure catalyst disclosed in this application can achieve efficient and stable rapid hydrogen evolution reaction under all pH conditions. Ru-H x WO 3NN can exhibit excellent HER catalytic performance under alkaline, neutral, and acidic electrolyte conditions (acidic: 129 mV, neutral: 219 mV, alkaline: 142 mV); in addition, it also shows ultra-high stability at an industrial-level current density (500 h+ @ 1 Acm -2 ). -2 ) BRIEF DESCRIPTION OF THE DRAWINGS

[0036] Figure 1 Sub-figure a is a schematic diagram of the synthesis process of the composite catalyst Ru-H x WO 3 NN-1 prepared in Example 1. Sub-figure b is an enlarged view of part A in sub-figure a, that is, a partial enlarged schematic diagram of nano-WO 3 . Sub-figure c is an enlarged view of part B in sub-figure a, that is, a partial enlarged schematic diagram of Ru-H x WO 3 NN

[0037] Figure 2 is a scanning electron microscope photograph of the composite catalyst Ru-H x WO 3 NN-1 prepared in Example 1

[0038] Figure 3 is a transmission electron microscope photograph of the composite catalyst Ru-H x WO 3 NN-1 prepared in Example 1. Sub-figures a and b are transmission electron microscope photographs at different scales

[0039] Figure 4 In sub-figure a, it is a high-resolution transmission electron microscope photograph of Ru-H x WO 3 NN-1 prepared in Example 1. Sub-figure b is a spherical aberration electron microscope photograph of Ru-H x WO 3 NN-1 and the corresponding elemental distribution map. Sub-figure c is an XRD spectrum of Ru-H x WO 3 NN-1. Sub-figure d is a Raman spectrum of Ru-H x WO 3 NN-1

[0040] Figure 5 is a catalytic performance diagram of the composite catalyst Ru-H x WO 3 NN-1 prepared in Example 1. Among them, sub-figure a is for Ru-H x WO 3 NN-1 and the corresponding comparative catalyst in 0.5 M H 2 SO4 HER catalytic performance diagram in a medium environment; Subfigure b is Ru-H x WO 3 HER catalytic performance diagram of WO x WO 3 HER catalytic performance diagram of WO x WO 3 Catalytic stability test diagram of WO Detailed implementation mode

[0041] In order to enable those of ordinary skill in the art to better understand the technical solutions of the present invention, the technical solutions of the present invention will be further described below in conjunction with the accompanying drawings and embodiments.

[0042] Example 1

[0043] This example discloses a preparation method of a cathode hydrogen evolution catalyst for all-pH electrolyzed water. The prepared catalyst is a composite structure catalyst formed by loading proton-blocking metal active site Ru nanoparticles (RuNPs) on a non-proton-blocking tungsten oxide (H x WO 3 ) support, and this composite structure grows on a copper foam conductive substrate. The synthesis process refers to Figure 1 , and the specific preparation steps are as follows:

[0044] 1) Pretreat the substrate: Cut the copper foam (CF) to a suitable size (2 cm × 4 cm), first place it in 1 M dilute hydrochloric acid and ultrasonically treat it for 20 min to remove the surface oxide layer, then place the copper foam in acetone and ultrasonically treat it for 30 min to remove the surface organic dirt, ultrasonically wash it in ultrapure water for 30 min to wash away the excess acetone on the surface, and finally store the copper foam in ethanol for later use.

[0045] 2) Preparation of nano-WO 3 : Weigh 0.9900 g of sodium tungstate dihydrate, add it to 30 mL of ultrapure water, then add an 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. Transfer it to a polytetrafluoroethylene reaction kettle liner (volume: 50 mL), put the copper foam substrate treated in step 1) into the solution, place it in a stainless steel high-pressure reaction kettle, and perform a hydrothermal reaction at 180 °C for 16 h. After cooling to room temperature, take out the copper foam grown with nano-tungsten oxide, wash it several times with ultrapure water and ethanol, and dry it at 75 °C overnight;

[0046] 3) Prepare Ru solution: weigh 250 mg of RuCl 3 ·xH 2 O was dissolved in 100 mL of 0.1 M HCl to prevent the hydrolysis of Ru and stirred for 30 min to mix well;

[0047] 4) Ru impregnation: The loaded nano-WO prepared in step 2) 3 The foam copper was cut into a size of 1 cm × 2 cm, placed in 10 mL of the Ru solution prepared in step 3), immersed for 60 min, taken out and washed with ultrapure water and ethanol respectively, and dried at 75 ° C overnight;

[0048] 5) Thermal hydrogenation of the carrier and reduction of the metal: The dried sample prepared in step 4) was placed in a tube furnace at 100 mL min -1 High purity H 2 Atmosphere (hydrogen volume ratio> 99.9%), 5℃min -1 The temperature was raised to 400°C at a rate of 1.50°C, and the sample was taken out after being cooled to room temperature. Thus, a composite catalyst with metal Ru supported on a tungsten oxide carrier rich in lattice hydrogen was obtained.

[0049] Figure 2 , Figure 3 The scanning electron microscope image and the transmission electron microscope image of the composite structure catalyst prepared in this embodiment are respectively Figure 3 Neutron image b shows that nanoparticles are loaded on the surface of the carrier and combined with Figure 2-3 It can be seen that the tungsten oxide (H x WO 3 ) is in the shape of a nanoneedle, with a tip diameter of about 20 nm, a tail diameter of about 100 nm, and a length of several microns; loaded on H x WO 3 The Ru nanoparticles (Ru NPs) on the surface of the composite catalyst are metal active sites, and the size is about 2-10 nm. Since the carrier morphology of the composite catalyst prepared in this embodiment is nanoneedle-shaped (NN), the composite material prepared in this embodiment is recorded as Ru-H x WO 3 NN-1, Ru-H on substrate x WO 3 The loading capacity of NN-1 was about 8.0 mg cm -2 .

[0050] Figure 4 Neutron images a and b are Ru-H x WO 3High-resolution transmission electron microscope images and aberration-corrected electron microscope images of NN-1. It can be seen from both sub-figures that Ru nanoparticles are supported on H x WO 3 support; Then look at the XRD pattern of Ru-H x WO 3 NN-1 ( Figure 4 In sub-figure c), the positive shift of the peak at 23.2° confirms the insertion of H; Figure 4 Sub-figure d is the Raman spectrum of Ru-H x WO 3 NN-1. From the figure, the peak at 1580 cm -1 corresponds to the WO-H peak, confirming the existence of lattice H.

[0051] Comparative Example 1

[0052] The difference between this comparative example and Example 1 is that proton-blocking metal active site Ru nanoparticles (RuNPs) are not supported on the non-proton-blocking tungsten oxide (H x WO 3 ) support with rich lattice hydrogen. The specific preparation process is as follows:

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

[0054] 2) Preparation of nano-WO 3 : The process is the same as step 2) of Example 1;

[0055] 3) Thermal hydrogenation of the support: The dried sample prepared in step 2) is placed in a tube furnace, and high-purity H -1 is introduced at a flow rate of 100 mL min 2 atmosphere, and the temperature is raised to 400 °C at a rate of 5 °C min -1 , and thermally reduced for 2 h. After cooling to room temperature, the sample is taken out. That is, a tungsten oxide nanoneedle catalytic material with rich lattice hydrogen is obtained, denoted as H x WO 3 NN.

[0056] Comparative Example 2

[0057] The difference between this comparative example and Example 1 is that the support tungsten oxide is not thermally hydrogenated, that is, protons are not pre-embedded in the WO 3 lattice to form lattice hydrogen. The specific preparation process is as follows:

[0058] 1)-4): The processes are the same as steps 1)-4) of Example 1.

[0059] 5) Reduction of only the metal: The dried sample prepared in step 4) is placed in 20 mg mL -1 of NaBH4 In the solution, it was treated for 20 min. After the treated sample was washed several times with ultrapure water and ethanol, it was dried again for 10 h. Thus, a composite structure catalyst with metallic Ru supported on a nanoneedle tungsten oxide support was obtained, denoted as Ru-WO 3 NN.

[0060] HER performance test: Three-electrode system: Ru-H x WO 3 NN-1 was cut into a size of 1 cm × 1 cm and used as the working electrode. This electrode was clamped on a platinum electrode clip, and 0.5 M H 2 SO 4 , 1 M PBS, and 1 M KOH solutions were used as electrolytes; Hg / Hg 2 SO 4 electrode, saturated calomel electrode (SCE), and Hg / HgO electrode were used as reference electrodes under acidic, neutral, and alkaline conditions, and a graphite rod was used as the counter electrode. HER test: Under the conditions of normal temperature and pressure, a 20 mL / min -1 N 2 gas flow was introduced for 20 min to remove other gases in the solution, and then cyclic voltammetry scanning (-0.2 to 0.2 V (vs. RHE), scan rate 20 mV / s) was performed for 30 cycles to activate the catalyst, followed by LSV testing to determine the HER overpotential.

[0061] Comparative catalyst Ru-WO 3 NN, H x WO 3 NN, Pt / C, and Ru / C were tested for HER performance in the same way as above.

[0062] Figure 5 Subfigures a-c of the neutron images respectively show the comparative data of the HER catalytic performance of Ru-H x WO 3 NN-1 (labeled as Ru-H x WO 3 NN in the figure) and the corresponding comparative catalysts in 0.5 M H 2 SO 4 , 1 M PBS, and 1 M KOH medium environments. The ordinate represents the current density, and the abscissa represents the voltage compared with the reversible hydrogen electrode. From subfigures a-c, under the above reaction conditions, Ru-H x WO 3 NN-1 can achieve 10 mA / cm 2 SO 4 at overpotentials of 12 mV, 28 mV, and 14 mV respectively in 0.5 M H -2Current density, and achieving an industrial-grade current density of 1 A cm⁻² at overpotentials of 129 mV, 219 mV, and 142 mV respectively. Subfigure d shows the catalyst Ru-H -2 WO x WO 3 NN-1 (labeled as Ru-H x WO 3 NN)、Ru-WO 3 NN, Pt / C, and Ru / C. From the graph, it can be seen that the catalytic performance of Ru-H x WO 3 NN-1 prepared in Example 1 is more superior. Subfigure e shows the chronopotentiometry graph of Ru-H x WO 3 NN-1 at a current density of 1 A cm⁻². The ordinate in the graph represents the electrolytic cell voltage, and the abscissa represents the duration of water electrolysis. From this graph, it can be known that the catalyst Ru-H -2 WO x WO 3 NN-1 prepared in Example 1 can stably catalyze for more than 500 h under the current density condition of 1 A cm⁻², with high stability. -2 The current density condition of 1 A cm⁻² can stably catalyze for more than 500 h, with 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 cation sulfate used in the hydrothermal method for preparing nano-WO 3 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-WO 3 : Weigh 0.8900 g of ammonium metatungstate, add it to 30 mL of ultrapure water, then add an appropriate amount of hydrochloric acid to adjust the pH to about 1.0. Subsequently, stir for 20 min, then add 1.0580 g of oxalic acid dihydrate, 1.0575 g of ammonium sulfate, and 2.2720 g of sodium sulfate, and stir for another 20 min. Transfer it to the inner lining of a polytetrafluoroethylene reaction kettle (volume: 50 mL). Put the foam copper substrate treated in step 1) into the solution, place it in a stainless steel high-pressure reaction kettle, and carry out hydrothermal reaction at 180 °C for 16 h. After cooling to room temperature, take out the foam copper with grown nano-tungsten oxide, wash it several times with ultrapure water and ethanol, and dry it overnight at 75 °C.

[0066] The carrier morphology of the composite catalyst prepared in this example is also nanoneedle-like (NN). The obtained catalyst is denoted as Ru-H x WO 3 NN-2. The Ru-H x WO 3The loading of NN-2 is about 12.5 mg cm -2 .

[0067] HER test: The test method is the same as above. Ru-H x WO 3 NN-2 can achieve a current density of 10 mA cm 2 SO 4 at overpotentials of 21 mV, 42 mV, and 27 mV in 0.5 M H -2 SO -2 , 1 M PBS, and 1 M KOH electrolyte environments respectively, and can achieve an industrial current density of 1 A cm -2 at overpotentials of 179 mV, 299 mV, and 202 mV respectively, and can stably catalyze for more than 400 h at a current density of 1 A cm

[0068] Example 3

[0069] The difference between this example and Example 1 is only that the cation sulfate used in the hydrothermal reaction to prepare nano-WO 3 is only ammonium sulfate, and other steps remain unchanged. The specific process of step 2) is as follows:

[0070] 2) Preparation of nano-WO 3 : Weigh 0.9900 g of sodium tungstate dihydrate, add it to 30 mL of ultrapure water, then add an appropriate amount of hydrochloric acid to adjust the pH to about 1.0, then stir for 20 min, add 1.0580 g of oxalic acid dihydrate and 1.5857 g of ammonium sulfate, stir for another 20 min, transfer it to the inner lining of a polytetrafluoroethylene reaction kettle (volume: 50 mL), put the foam copper substrate treated in step 1) into the solution, place it in a stainless steel high-pressure reaction kettle, carry out hydrothermal reaction at 180 °C for 16 h, after cooling to room temperature, take out the foam copper with grown nano-tungsten oxide, wash it several times with ultrapure water and ethanol, and dry it overnight at 75 °C.

[0071] The carrier morphology of the composite catalyst prepared in this example is nano-wire (NW), with a diameter of about 80 nm. The obtained catalyst is denoted as Ru-H x WO 3 NW-1. The loading of Ru-H x WO 3 NW-1 on the substrate is about 8.0 mg cm -2 .

[0072] HER test: The test method is the same as above. Ru-H x WO 3 NW-1 can achieve a current density of 10 mA cm 2 SO 4, 1 M PBS, 1 M KOH medium environments, respectively at overpotentials of 41 mV, 72 mV, and 39 mV to achieve a current density of 10 mA cm -2 and can stably catalyze for more than 200 h under the condition of a current density of 10 A cm -2 .

[0073] Example 4

[0074] The difference between this example and Example 1 is only that the cation sulfate used in the hydrothermal reaction to prepare nano-WO 3 is only sodium sulfate, and other steps remain unchanged. The specific process of step 2) is as follows:

[0075] 2) Preparation of nano-WO 3 : Weigh 0.9900 g of sodium tungstate dihydrate, add it to 30 mL of ultrapure water, then add an 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, stir for another 20 min, transfer it to the inner lining of a polytetrafluoroethylene reaction kettle (volume: 50 mL), put the foam copper substrate treated in step 1) into the solution, place it in a stainless steel high-pressure reaction kettle, carry out hydrothermal reaction at 180 °C for 16 h, after cooling to room temperature, take out the foam copper grown with nano-tungsten oxide, wash it several times with ultrapure water and ethanol, and dry it overnight at 75 °C.

[0076] The carrier morphology of the composite catalyst prepared in this example is nanorod-shaped (NR), with a diameter of about 200 nm. The obtained catalyst is denoted as Ru-H x WO 3 NR-1, and the loading of Ru-H x WO 3 NR-1 on the substrate is about 8.0 mg cm -2 .

[0077] HER test: The test method is the same as above. Ru-H x WO 3 NR-1 can achieve a current density of 10 mA cm 2 in 0.5 M H 4 SO -2 , 1 M PBS, 1 M KOH medium environments, respectively at overpotentials of 72 mV, 109 mV, and 77 mV, and can stably catalyze for more than 200 h under the condition of a current density of 10 A cm -2 .

[0078] Example 5

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

[0080] 3) Prepare the Ru solution: Weigh 520 mg of K 3 RuCl 6 , dissolve it in 100 mL of 0.1 M HCl to prevent hydrolysis of Ru, and stir for 30 min to mix evenly.

[0081] The carrier morphology of the composite catalyst prepared in this example is nanoneedle-shaped (NN), and the obtained catalyst is denoted as Ru-2-H x WO 3 NN, and the loading of Ru-2-H x WO 3 NN on the substrate is about 8.1 mg cm -2 .

[0082] HER test: The test method is the same as above. Ru-2-H x WO 3 NN can achieve a current density of 10 mA cm 2 SO 4 at overpotentials of 19 mV, 36 mV, and 25 mV respectively in 0.5 M H -2 SO -2 , 1 M PBS, and 1 M KOH medium environments, and can achieve a current density of 1 mA cm -2 at overpotentials of 151 mV, 271 mV, and 182 mV respectively, and can stably catalyze for more than 200 h under the condition of a current density of 1 A cm

[0083] Example 6

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

[0085] 3) Prepare the Ru solution: Weigh 520 mg of K 2 RuCl 6 , dissolve it in 100 mL of 0.1 M HCl to prevent hydrolysis of Ru, and stir for 30 min to mix evenly.

[0086] The carrier morphology of the composite catalyst prepared in this example is nanoneedle-shaped (NN), and the obtained catalyst is denoted as Ru-3-H x WO 3 NN, and the loading of Ru-3-H x WO 3 NN on the substrate is about 8.2 mg cm-2 。

[0087] HER test: The test method is the same as above, Ru-3-H x WO 3 NN can achieve a current density of 10 mA cm 2 SO 4 at overpotentials of 22 mV, 32 mV, and 27 mV respectively in 0.5 M H -2 SO -2 media environments of 1 M PBS and 1 M KOH, and can achieve a current density of 1 mA cm -2 at overpotentials of 144 mV, 250 mV, and 177 mV respectively, and can stably catalyze for more than 200 h under a current density of 1 A cm

[0088] Example 7

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

[0090] 3) Prepare Ir solution: Weigh 250 mg of IrCl 3 , dissolve it in 100 mL of 0.1 M HCl to prevent hydrolysis of Ir, and stir for 30 min to mix evenly.

[0091] 4) Impregnate Ir: Cut the copper foam loaded with nano-WO 3 prepared in step 2) into a size of 1 cm × 2 cm, place it in 10 mL of the Ir solution prepared in step 3), impregnate for 60 min, take it out, wash it with ultrapure water and ethanol respectively, and dry it overnight at 75 °C.

[0092] The carrier morphology of the composite catalyst prepared in this example is nanoneedle-shaped (NN), and the obtained catalyst is denoted as Ir-H x WO 3 NN, and the loading of Ir-H x WO 3 NN on the substrate is about 8.0 mg cm -2 。

[0093] HER test: The test method is the same as above, Ir-HxWO 3 NN can achieve a current density of 10 mA cm 2 SO 4 at overpotentials of 50 mV, 62 mV, and 52 mV respectively in 0.5 M H -2 SO-2 current density, and can stably catalyze for more than 24 h under the condition of 1 A cm -2 current density condition.

[0094] Example 8

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

[0096] 3) Prepare a Pt solution: Weigh 300 mg of H 2 PtCl 6 , dissolve it in 100 mL of 0.1 M HCl, and stir for 30 min to mix evenly.

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

[0098] The carrier morphology of the composite catalyst prepared in this example is nanoneedle-shaped (NN), and the obtained catalyst is denoted as Pt-H x WO 3 NN, and the loading of Pt-H x WO 3 NN on the substrate is about 8.0 mg cm -2 .

[0099] HER test: The test method is the same as above. Pt-H x WO 3 NN can achieve a current density of 10 mA cm 2 SO 4 in 0.5 M H -2 at overpotentials of 18 mV, 39 mV, and 29 mV respectively in 1 M PBS and 1 M KOH medium environments, and can achieve an industrial-level current density of 1 mA cm -2 at overpotentials of 152 mV, 265 mV, and 187 mV respectively, and can stably catalyze for more than 24 h under the condition of 1 A cm -2 current density.

[0100] It can be seen from the test data of Examples 1-8 that the metal-oxide composite structure catalysts prepared in the examples of this application can all be used for water electrolysis under full pH conditions, with reduced dependence on the acid-base environment and excellent HER activity.

[0101] In addition, the composition of the proton-blocking metal active sites supported on the carrier and the morphology of the non-proton-blocking tungsten oxide (H x WO 3 ) carrier rich in lattice hydrogen will directly affect the cathodic hydrogen evolution reaction (HER) activity of the composite structure catalyst under all pH conditions. The composition of the proton-blocking metal active sites is preferably ruthenium nanoparticles with a size of 2-10 nm. H x WO 3 The morphology of the carrier is preferably nanoneedle-shaped, with a tip of about 20 nm, a tail end of about 100 nm, and a length of several micrometers. The composite structure catalyst prepared under these conditions exhibits low overpotential and high stability at industrial-level current density during the cathodic hydrogen evolution reaction (HER) of all-pH electrolyzed water.

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

Claims

1. A method for preparing a cathode hydrogen evolution catalyst for full pH water electrolysis, characterized in that: The steps include: 1) Pretreatment of the foam copper substrate; 2) Dissolve tungstate in water, adjust the solution pH to 0.8-2, stir, add oxalic acid and cationic sulfate, stir evenly to obtain a precursor solution; 3) placing the pretreated copper foam substrate into a precursor solution for hydrothermal reaction, taking out the sample after the reaction, washing and drying, and obtaining a copper foam with nano-WO3 deposited thereon; 4) preparing a metal source solution; 5) Put the foam copper with nano-WO3 deposited into the metal source solution and immerse it for 50 to 70 minutes, then take it out, wash it and dry it; 6) The sample obtained in the previous step is placed in a tubular furnace and calcined in a reducing atmosphere containing H2 to perform thermal hydrogenation of the WO3 substrate and reduction of the metal to form a metal-oxide composite structure, i.e., the final product catalyst.

2. The method for preparing a cathode hydrogen evolution catalyst for full pH water electrolysis according to claim 1, wherein: In step 2), the tungstate is any one of sodium tungstate, ammonium metatungstate, and potassium tungstate; the cationic sulfate is selected from 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 to 20 g / L.

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

4. The method for preparing a cathode hydrogen evolution catalyst for full pH water electrolysis according to claim 1, wherein: The temperature for the hydrothermal reaction in step 3) is 160-200° C., and the hydrothermal reaction time is 6-36 hours.

5. The method for preparing a cathode hydrogen evolution catalyst for full pH water electrolysis according to claim 1, characterized in that: In step 6), the calcination temperature is 300-500° C., the hydrogen content in the reducing atmosphere is 10% to 100%, and the rest is argon.

6. The method for preparing a cathode hydrogen evolution catalyst for full pH water electrolysis according to claim 2, wherein: In step 4), the ruthenium source is any one or more of anhydrous ruthenium chloride, hydrated ruthenium chloride, potassium hexachlororuthenate (trivalent), and potassium hexachlororuthenate (tetravalent); the platinum source is any one of anhydrous platinum chloride, hydrated platinum chloride, chloroplatinic acid, and potassium hexachloroplatinate; the iridium source is any one of anhydrous iridium chloride (trivalent or tetravalent), hydrated iridium chloride (trivalent or tetravalent), chloroiridic acid, and potassium hexachloroiridate (trivalent or tetravalent).

7. A cathode hydrogen evolution catalyst for full pH water electrolysis, characterized in that: The catalyst is prepared according to the preparation method described in any one of claims 1 to 6. The catalyst is a catalytic material with a metal-oxide composite structure, specifically a non-proton-blocking metal oxide H rich in lattice hydrogen. x WO3 is used as a carrier, and ruthenium, platinum or iridium nanoparticles are loaded on the carrier as proton-blocking metal active sites. The composite structure is grown on a foam copper conductive substrate.

8. The cathode hydrogen evolution catalyst for full pH water electrolysis according to claim 7, characterized in that: H x The morphology of the WO3 carrier is nano-needle, nano-wire or nano-rod. x The morphology of the WO3 support is controlled by adjusting the cation composition and concentration during the hydrothermal process; the size of the metal active sites is 2 to 10 nm; H x When the WO3 carrier morphology 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 WO3 carrier morphology is nanowire-like, the diameter of the nanowire is 70-90 nm; H x When the WO3 carrier morphology is in the shape of nanorods, the diameter of the nanorods is 180 to 220 nm.

9. The cathode hydrogen evolution catalyst for full pH water electrolysis according to claim 8, characterized in that H x The morphology of the WO3 carrier is nano-needle-shaped, and the metal active sites loaded on the carrier are ruthenium nanoparticles.

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

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