Method for preparing tungsten oxide supported platinum catalyst through photo-reduction and application of tungsten oxide supported platinum catalyst in electrochemical seawater hydrogen evolution

Abstract

The invention belongs to the technical field of hydrolysis hydrogen production, and particularly relates to a method for preparing a tungsten oxide supported platinum catalyst through photoreduction and application of the tungsten oxide supported platinum catalyst in electrochemical seawater hydrogen evolution. According to the tungsten oxide loaded platinum catalyst (Pt / WO3) prepared by using an in-situ photoreduction strategy, the WO3 carrier can promote dissociation of water, and the microenvironment around Pt nanoparticles can be regulated and controlled by enriching hydrogen ions, so that the hydrogen evolution reaction energy barrier is reduced, and the catalyst performance is improved. In addition, due to protection of the WO3 carrier, the Pt / WO3 catalyst can effectively avoid corrosion of chloride ions in seawater, so that the stability of the catalyst is improved. Therefore, when the Pt / WO3 is applied to seawater electrolysis hydrogen evolution, the overpotential of the Pt / WO3 is only 298mV under 10mA. Cm <-2 >, the mass activity of the Pt / WO3 is 7 times that of commercial Pt / C, and the Pt / WO3 has long-term stability as long as 140 hours and shows excellent seawater electrolysis hydrogen evolution activity and stability.

Description

Technical Field

[0001] The invention belongs to the technical field of hydrogen production by hydrolysis, and specifically relates to a method for preparing a tungsten oxide-supported platinum catalyst by photoreduction and an application of the method in electrochemical hydrogen evolution from seawater. Background Art

[0002] Hydrogen has a high energy density (≈141.6MJkg -1 ), cleanliness and renewability, it is widely regarded as one of the most promising energy sources to alleviate the energy crisis and climate problems. However, 96% of industrial hydrogen is currently produced by steam methane reforming, methanol reforming and coal gasification, which will lead to a large amount of non-renewable energy consumption and carbon dioxide emissions, and is therefore an unsustainable way of producing hydrogen. The electrochemical method of hydrogen production is a sustainable and clean way to produce hydrogen fuel by water-hydrogen / oxygen cycle due to its low reaction activation energy, high reaction rate and energy efficiency, which is crucial to promoting the development of renewable energy technology.

[0003] At present, commercial water splitting technologies based on electrolysis, such as proton exchange membrane (PEM) electrolyzers and alkaline electrolyzers, mainly use high-purity water as a reactant. However, if a large amount of fresh water is used for electrolysis, it is very likely to lead to a shortage of fresh water resources. In contrast, seawater accounts for 96.5% of the earth's water reserves and is an almost inexhaustible resource and natural electrolyte raw material. Therefore, if seawater can be used directly as an electrolyte or a conductive electrolyte is added, the cost of electrolyzing water can be significantly reduced, and it has the effect of desalinating seawater. However, due to the complexity of natural seawater, direct electrolysis of seawater is still in its infancy.

[0004] Water splitting to produce hydrogen includes two half reactions, namely the hydrogen evolution reaction (HER) at the cathode and the oxygen evolution reaction (OER) at the anode. However, the slow kinetics of OER and HER hinder the application of seawater splitting, especially in neutral electrolytes. At the same time, compared with freshwater splitting, seawater splitting catalysts face more challenges. On the one hand, due to the lack of H+ in neutral seawater, additional energy is required to split water, thereby increasing energy consumption. On the other hand, chloride ions in seawater can also poison the catalyst.

[0005] Due to the above-mentioned thorny obstacles, there are few reports on HER catalysts in natural seawater, and little progress has been made so far. The general design criteria for seawater splitting electrocatalysts currently involve the following key aspects: (1) catalyst dimensions; (2) surface chemistry, such as heterostructure, doping engineering, defect engineering, alloying engineering, crystal phase engineering, etc.; (3) electron transfer pathways. However, in most cases, these traditional strategies can only adjust the atomic structure and electronic state of the HER catalyst, thereby adjusting its catalytic properties in a milder way. The local reaction environment around the catalyst plays a crucial role in the electrode process and is an important breakthrough in the development of new seawater splitting electrocatalysts. Summary of the invention

[0006] In order to overcome the shortcomings of the above-mentioned prior art, the present invention adopts an in-situ photoreduction strategy to prepare a tungsten oxide-supported platinum catalyst (Pt / WO3), wherein the WO3 carrier can not only promote the dissociation of water, but also regulate the microenvironment around the Pt nanoparticles by enriching hydrogen ions, thereby reducing the energy barrier of the hydrogen evolution reaction and improving the catalyst performance. In addition, due to the protection of the WO3 carrier, the Pt / WO3 catalyst can effectively avoid the corrosion of chloride ions in seawater, thereby improving the stability of the catalyst.

[0007] In order to achieve the above object, the technical solution adopted by the present invention is:

[0008] The first aspect of the present invention provides a method for preparing a tungsten oxide-supported platinum catalyst by photoreduction, the method comprising the following steps:

[0009] S1. Dissolve sodium tungstate in water, add hydrochloric acid for aging, wash and centrifuge until the filtrate is neutral, dry and grind the obtained product, and then calcine to prepare tungsten oxide;

[0010] S2. Grind the tungsten oxide powder and dissolve it in water, then add chloroplatinic acid solution, mix well and irradiate the solution with a xenon lamp. After washing and drying the obtained sample, a catalyst Pt / WO3 in which photoreduced platinum is loaded on tungsten oxide is obtained.

[0011] Preferably, in S1, the concentration of sodium tungstate in water is 1-2 mol / L, the concentration of hydrochloric acid is 2-4 mol / L, and the volume ratio of sodium tungstate aqueous solution to hydrochloric acid is 1:8-10.

[0012] Preferably, in S1, the aging treatment time is 1-2 hours.

[0013] Preferably, in S1, the calcination is carried out in an air atmosphere, the calcination temperature is 300-400°C, and the calcination time is 1-2h.

[0014] Preferably, in S2, the concentration of tungsten oxide powder in water is 5 mg / 4-7 mL.

[0015] Preferably, in S2, the concentration of the chloroplatinic acid solution is 0.1-0.2 g / mL.

[0016] Preferably, in S2, the dosage ratio of the tungsten oxide aqueous solution to the chloroplatinic acid solution is 2-10 mL: 2-10 μL.

[0017] Preferably, in S2, the illumination time of the xenon lamp is 2-8 hours, and the power is 200-400W.

[0018] The second aspect of the present invention provides a tungsten oxide-supported platinum catalyst prepared by the method described in the first aspect.

[0019] The third aspect of the present invention provides the use of the tungsten oxide-supported platinum catalyst described in the second aspect in the electrolysis of neutral seawater for hydrogen evolution.

[0020] Compared with the prior art, the present invention has the following beneficial effects:

[0021] The present invention utilizes an in-situ photoreduction strategy to prepare a tungsten oxide-supported platinum catalyst (Pt / WO3), that is, sodium tungstate is first subjected to an aging treatment with hydrochloric acid, then calcined to obtain tungsten oxide, and then the obtained tungsten oxide is dissolved in a chloroplatinic acid solution, and finally subjected to xenon lamp irradiation to obtain Pt / WO3. In the prepared Pt / WO3, the WO3 carrier can not only promote the dissociation of water, but also regulate the microenvironment around the Pt nanoparticles by enriching hydrogen ions, thereby reducing the energy barrier of the hydrogen evolution reaction and improving the catalyst performance. In addition, due to the protection of the WO3 carrier, the Pt / WO3 catalyst can effectively avoid the corrosion of chloride ions in seawater, thereby improving the stability of the catalyst. Therefore, when the Pt / WO3 catalyst prepared by the present invention is applied to the electrolysis of seawater for hydrogen evolution, it has a high thermal conductivity at 10 mA·cm -2 The overpotential is only 298 mV, the mass activity is 7 times that of commercial Pt / C, and it has long-term stability of up to 140 h, showing excellent activity and stability for hydrogen evolution in seawater electrolysis. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 It is the transmission electron microscope image of Pt / WO3;

[0023] Figure 2 It is the element distribution diagram of Pt / WO3;

[0024] Figure 3 This is the X-ray electron diffraction comparison diagram of Pt / WO3 and standard card;

[0025] Figure 4This is the linear sweep voltammetry curve of hydrogen evolution of Pt / WO3 in simulated seawater, where the abscissa is the overpotential relative to the standard hydrogen electrode and the ordinate is the current density;

[0026] Figure 5 This is a stability comparison diagram of Pt / WO3 and commercial Pt / C obtained by chronopotentiometry in simulated seawater, where the abscissa is time and the ordinate is the overpotential relative to the standard hydrogen electrode;

[0027] Figure 6 Pt / WO3 and commercial Pt / C at 10 mA·cm -2 The overpotential and Tafel slope comparison diagram under ;

[0028] Figure 7 In-situ Raman spectra test diagram of Pt / WO3, commercial Pt / C and WO3;

[0029] Figure 8 These are the in-situ infrared spectrum test diagrams of Pt / WO3, commercial Pt / C and WO3. DETAILED DESCRIPTION

[0030] The specific embodiments of the present invention are further described below. It should be noted that the description of these embodiments is used to help understand the present invention, but does not constitute a limitation of the present invention. In addition, the technical features involved in each embodiment of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0031] The experimental methods in the following examples are conventional methods unless otherwise specified, and the experimental materials used in the following examples are commercially available unless otherwise specified.

[0032] Example 1: A method for preparing tungsten oxide-supported platinum catalyst by photoreduction

[0033] (1) Weigh 6.597g of sodium tungstate and dissolve it in 20mL of deionized water (1mol / L). After it is completely dissolved, add it into 180mL of hydrochloric acid (3mol / L) and age it for 1h. Then, ultrasonically wash it with deionized water and anhydrous ethanol three times respectively and centrifuge it until the filtrate is neutral. Then, place the obtained sample at 60℃ and vacuum dry it for 12h. After it is completely dried, grind the sample, and then place the sample in a tube furnace with a porcelain boat and calcine it at 350℃ for 1h in an air atmosphere to obtain tungsten oxide.

[0034] (2) Weigh 50 mg of the prepared tungsten oxide powder, grind it, add 50 mL of deionized water, and ultrasonicate it for 10 min to make it evenly dispersed. Then add 80 μL of chloroplatinic acid solution (0.1 g / mL) and stir it for 20 min. Then, use a xenon lamp (Purphil PLS-SEX300+, power 300 W) to illuminate the solution for 8 h. The obtained sample is centrifuged and ultrasonically cleaned with deionized water for 3 times. Finally, after vacuum drying for 12 h, the tungsten oxide-supported platinum catalyst is obtained.

[0035] The prepared Pt / WO3 was observed by transmission electron microscopy, and the instrument model used was the American ThermoFisher Talos F200X G2. Figure 1 As shown in the figure, the uniform distribution of Pt nanoparticles on the WO3 nanosheets can be seen from the surface morphology at a scale of 50 nm. The energy spectrum element distribution analysis is also performed, as shown in the figure. Figure 2 As shown in the figure, the uniform distribution of W, O, and Pt can be seen. In addition, the X-ray electron diffraction test of Pt / WO3 was carried out, and the instrument model used was Rigaku UltimaIV. Figure 3 As shown, WO3 corresponds well to the standard card, but there is no obvious Pt peak, which is caused by the extremely low Pt content. The above test results prove that the prepared sample is tungsten oxide nanosheets loaded with platinum nanoparticles.

[0036] Example 2: A method for preparing tungsten oxide-supported platinum catalyst by photoreduction

[0037] (1) Weigh 6.597g of sodium tungstate and dissolve it in 20mL of deionized water. After it is completely dissolved, add it into 180mL of hydrochloric acid (3mol / L) and age it for 1h. Then ultrasonically wash it with deionized water and anhydrous ethanol three times respectively and centrifuge it until the filtrate is neutral. Then place the obtained sample at 60℃ and vacuum dry it for 12h. After it is completely dried, grind the sample, and then put the sample into a tube furnace with a porcelain boat. After calcining it at 350℃ for 1h in air atmosphere, tungsten oxide is obtained.

[0038] (2) Weigh 50 mg of the prepared tungsten oxide powder, grind it, add 50 mL of deionized water, and ultrasonicate it for 10 min to make it evenly dispersed. Then add 60 μL of chloroplatinic acid solution (0.1 g / mL), stir it for 20 min, and then illuminate the solution with a xenon lamp for 6 h. The obtained sample is centrifuged and ultrasonically cleaned with deionized water for 3 times. Finally, after vacuum drying for 12 h, the tungsten oxide-supported platinum catalyst is obtained.

[0039] Transmission electron microscopy, element distribution and X-ray electron diffraction analysis also confirmed that the prepared sample was tungsten oxide nanosheets loaded with platinum nanoparticles.

[0040] Example 3: A method for preparing tungsten oxide-supported platinum catalyst by photoreduction

[0041] (1) Weigh 6.597g of sodium tungstate and dissolve it in 20mL of deionized water. After it is completely dissolved, add it into 180mL of hydrochloric acid (3mol / L) and age it for 1h. Then ultrasonically wash it with deionized water and anhydrous ethanol three times respectively and centrifuge it until the filtrate is neutral. Then place the obtained sample at 60℃ and vacuum dry it for 12h. After it is completely dried, grind the sample, and then place the sample in a tube furnace with a porcelain boat and calcine it at 350℃ in air atmosphere for 1h to obtain tungsten oxide.

[0042] (2) Weigh 50 mg of the prepared tungsten oxide powder, grind it, add 50 mL of deionized water, and ultrasonicate it for 10 min to make it evenly dispersed. Then add 100 μL of chloroplatinic acid solution (0.1 g / mL), stir it for 20 min, and then illuminate the solution with a xenon lamp for 10 h. The obtained sample is centrifuged and ultrasonically cleaned with deionized water for 3 times. Finally, after vacuum drying for 12 h, the tungsten oxide-supported platinum catalyst is obtained.

[0043] Transmission electron microscopy, element distribution and X-ray electron diffraction analysis also confirmed that the prepared sample was tungsten oxide nanosheets loaded with platinum nanoparticles.

[0044] Experimental example: electrochemical test

[0045] The electrochemical test adopted a three-electrode system, the test instrument was AUTOLAB (model AUT88171), the electrolyte was neutral simulated seawater (3.5% NaCl), Ag / AgCl was used as the reference electrode, the carbon rod was used as the counter electrode, and the working electrode was the Pt / WO3 prepared in Example 1. After the circuit was connected, the program was set, and Linear sweep voltammetry potentiostatic was selected for hydrogen evolution test. The potential range was set to -0.6 to -1.2 V, the scan rate was 0.005 V / s, and a linear sweep voltammetry (LSV) curve was drawn.

[0046] Figure 4 The linear sweep voltammetric curve of hydrogen evolution of Pt / WO3 in 3.5% NaCl neutral simulated seawater is shown. It can be seen from the figure that Pt / WO3 has good hydrogen evolution performance in neutral simulated seawater, which is significantly better than commercial Pt / C.

[0047] Figure 5 This is a stability comparison chart of Pt / WO3 and commercial Pt / C obtained by chronopotentiometry in simulated seawater. It can be seen from the figure that the Pt / WO3 catalyst has a long-term stability of 140h, which is significantly better than commercial Pt / C.

[0048] Figure 6Pt / WO3 and commercial Pt / C at 10 mA·cm -2 The overpotential and Tafel slope comparison diagram under 3D is shown. It can be seen from the figure that the overpotential and Tafel slope values ​​of Pt / WO3 are lower than those of commercial Pt / C, indicating that it has better hydrogen evolution activity and faster catalytic reaction kinetics than commercial Pt / C.

[0049] At the same time, in-situ Raman spectroscopy tests were performed on Pt / WO3, commercial Pt / C and WO3, and the instrument model used was Horiba LabRAM HR Evolution. Figure 7 As shown, compared with commercial Pt / C and WO3, hydrogen ions are enriched around Pt / WO3 during the electrolysis process, generating a local acidic environment.

[0050] In addition, in-situ infrared spectroscopy tests were performed on Pt / WO3, commercial Pt / C and WO3 using a Shimadzu IRXross FTIR Spectrophotometer. Figure 8 As shown, the local reaction environment during the electrolysis process can effectively avoid the corrosion of chloride ions in seawater, and can avoid the additional energy consumption of water dissociation by enriching hydrogen ions.

[0051] The embodiments of the present invention are described in detail above, but the present invention is not limited to the described embodiments. For those skilled in the art, various changes, modifications, substitutions and variations of these embodiments are made without departing from the principles and spirit of the present invention, and still fall within the protection scope of the present invention.

Claims

1. A method for preparing a tungsten oxide-supported platinum catalyst by photoreduction, characterized in that: The following steps are involved: S1. Dissolve sodium tungstate in water, add hydrochloric acid for aging, wash and centrifuge until the filtrate is neutral, dry and grind the obtained product, and then calcine to prepare tungsten oxide; S2. Grind the tungsten oxide powder and dissolve it in water, then add chloroplatinic acid solution, mix well and irradiate the solution with a xenon lamp. After washing and drying the obtained sample, a catalyst in which photoreduced platinum is loaded on tungsten oxide is obtained.

2. The method for preparing tungsten oxide-supported platinum catalyst by photoreduction according to claim 1, characterized in that: In S1, the concentration of sodium tungstate in water is 1-2 mol / L, the concentration of hydrochloric acid is 2-4 mol / L, and the volume ratio of sodium tungstate aqueous solution to hydrochloric acid is 1:8-10.

3. The method for preparing tungsten oxide-supported platinum catalyst by photoreduction according to claim 1, characterized in that: In S1, the aging treatment time is 1-2h.

4. The method for preparing tungsten oxide-supported platinum catalyst by photoreduction according to claim 1, characterized in that: In S1, the calcination is carried out in an air atmosphere at a temperature of 300-400° C. for a time of 1-2 h.

5. The method for preparing tungsten oxide-supported platinum catalyst by photoreduction according to claim 1, characterized in that: In S2, the concentration of tungsten oxide powder in water is 5 mg / 4-7 mL.

6. The method for preparing tungsten oxide-supported platinum catalyst by photoreduction according to claim 1, characterized in that: In S2, the concentration of the chloroplatinic acid solution is 0.1-0.2 g / mL.

7. The method for preparing tungsten oxide-supported platinum catalyst by photoreduction according to claim 1, characterized in that: In S2, the dosage ratio of the tungsten oxide aqueous solution to the chloroplatinic acid solution is 2-10 mL: 2-10 μL.

8. The method for preparing tungsten oxide-supported platinum catalyst by photoreduction according to claim 1, characterized in that: In S2, the illumination time of the xenon lamp is 2-8h and the power is 200-400W.

9. A tungsten oxide-supported platinum catalyst prepared by the method according to any one of claims 1 to 8.

10. Use of the tungsten oxide-supported platinum catalyst according to claim 9 in hydrogen evolution by electrolysis of neutral seawater.

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