A method for preparing tungsten oxide supported platinum catalyst by photoreduction and electrochemical seawater hydrogen evolution application thereof

Abstract

The application belongs to the technical field of hydrogen production by hydrolysis, and particularly relates to a method for preparing a tungsten oxide supported platinum catalyst by photoreduction and electrochemical seawater hydrogen evolution application thereof. The tungsten oxide supported platinum catalyst (Pt / WO3) prepared by using the in-situ photoreduction strategy, wherein the WO3 carrier can not only promote water dissociation, but also can regulate the microenvironment around the Pt nanoparticles by enriching hydrogen ions, thereby reducing the hydrogen evolution reaction energy barrier 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 is applied to electrolytic seawater hydrogen evolution, the overpotential thereof is only 298 mV at 10 mA·cm ‑2 , the mass activity is 7 times that of the commercial Pt / C, and has a long-term stability of up to 140 h, which shows excellent electrolytic seawater hydrogen evolution activity and stability.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of hydrogen production by hydrolysis, and particularly relates to a method for preparing a tungsten oxide loaded platinum catalyst by photoreduction and electrochemical seawater hydrogen evolution application thereof. BACKGROUND

[0002] Hydrogen is widely considered as one of the most promising energy sources to alleviate energy crisis and climate problems due to its high energy density (≈141.6 MJ kg -1 ), cleanliness and renewability. However, currently 96% of industrial hydrogen is produced from steam methane reforming, methanol reforming and coal gasification, which leads to a large amount of non-renewable energy consumption and carbon dioxide emissions, and thus is an unsustainable way of hydrogen production. Electrochemical method for hydrogen production is a sustainable and clean way to realize water-hydrogen / oxygen cycle production of hydrogen fuel due to its low reaction activation energy, high reaction rate and energy efficiency, and is crucial for promoting the development of renewable energy technology.

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

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

[0005] Due to these difficult obstacles, there are few reports of HER catalysts in natural seawater, and the progress so far is very limited. The current general design criteria for seawater splitting electrocatalysts mainly involve the following key aspects: (1) catalyst dimensionality; (2) surface chemistry, such as heterostructure, doping engineering, defect engineering, alloying engineering, and crystal phase engineering; (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 relatively mild manner. The local reaction environment around the catalyst plays a crucial role in the electrode process and is an important breakthrough for developing new seawater splitting electrocatalysts. SUMMARY

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

[0007] In order to achieve the above purpose, the technical scheme adopted by the present application is:

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

[0009] S1, dissolve sodium tungstate in water, then add hydrochloric acid for aging treatment, then 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, then dissolve it in water, then add chloroplatinic acid solution, mix well, then use a xenon lamp to irradiate the solution, and then wash and dry the obtained sample to obtain a catalyst with platinum supported on tungsten oxide, Pt / WO3.

[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 h.

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

[0014] Preferably, in S2, the concentration of the 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 ratio of the amount of the tungsten oxide aqueous solution to the chloroplatinic acid solution is 2-10 mL:2-10 μL.

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

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

[0019] The third aspect of the present application provides an application of the tungsten oxide supported platinum catalyst of the second aspect in electrolysis of neutral seawater to produce hydrogen.

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

[0021] The present application utilizes an in-situ photoreduction strategy to prepare a tungsten oxide supported platinum catalyst (Pt / WO3), i.e., first aging sodium tungstate with hydrochloric acid, then calcining to prepare tungsten oxide, then dissolving the obtained tungsten oxide in a chloroplatinic acid solution, and finally treating with a xenon lamp to obtain Pt / WO3. In the prepared Pt / WO3, the WO3 support not only promotes the dissociation of water, but also regulates the microenvironment around the Pt nanoparticles by enriching hydrogen ions, thereby reducing the energy barrier of the hydrogen evolution reaction and improving the performance of the catalyst. In addition, due to the protection of the WO3 support, 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 application is applied to electrolysis of seawater to produce hydrogen, the overpotential thereof is only 298 mV at 10 mA·cm -2 , the mass activity is 7 times that of commercial Pt / C, and has a long-term stability of up to 140 h, showing excellent electrolysis of seawater to produce hydrogen activity and stability. BRIEF DESCRIPTION OF DRAWINGS

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

[0023] Figure 2 is an element distribution map of Pt / WO3;

[0024] Figure 3 is an X-ray electron diffraction comparison map of Pt / WO3 with a standard card;

[0025] Figure 4Figure 4 is a linear sweep voltammogram of Pt / WO3 in simulated seawater, in which the abscissa is overpotential relative to a standard hydrogen electrode, and the ordinate is current density;

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

[0027] Figure 6 Figure 6 is a comparison chart of overpotential and Tafel slope of Pt / WO3 and commercial Pt / C at 10 mA-cm -2

[0028] Figure 7 Figure 7 is an in-situ Raman spectrum test chart of Pt / WO3, commercial Pt / C and WO3;

[0029] Figure 8 Figure 8 is an in-situ infrared spectrum test chart of Pt / WO3, commercial Pt / C and WO3. DETAILED DESCRIPTION

[0030] The specific embodiments of the present application are described below. It should be noted that the description of these embodiments is intended to help understand the present application, but does not constitute a limitation on the present application. In addition, the technical features involved in the various embodiments of the present application 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 all conventional methods unless otherwise specified. The test materials used in the following examples are all commercially available unless otherwise specified.

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

[0033] (1) 6.597 g of sodium tungstate was dissolved in 20 mL of deionized water (1 mol / L), and after complete dissolution, it was added to 180 mL of hydrochloric acid (3 mol / L) and aged for 1 h. Then it was washed with deionized water and anhydrous ethanol by ultrasonic three times and centrifuged until the filtrate was neutral. Then the obtained sample was placed in a vacuum dryer at 60°C for 12 h, and after complete drying, the sample was ground, and then the sample was placed in a porcelain boat in a tube furnace and calcined at 350°C for 1 h under air atmosphere to obtain tungsten oxide.

[0034] ​(2) 50 mg of the prepared tungsten oxide powder was weighed, ground and added to 50 mL of deionized water, and ultrasonically dispersed for 10 min, then 80 μL of chloroplatinic acid solution (0.1 g / mL) was added, stirred for 20 min, then the solution was irradiated with a xenon lamp (Polfly PLS-SEX300+, power 300 W) for 8 h. The obtained sample was centrifuged and washed with deionized water for 3 times by ultrasonic cleaning, and finally vacuum dried for 12 h to obtain a tungsten oxide supported platinum catalyst.

[0035] The prepared Pt / WO3 was observed by transmission electron microscopy, and the instrument used was a ThermoFisher Talos F200X G2 from the United States, as shown in FIG. 2A. From the surface morphology map at a scale of 50 nm, it can be seen that the Pt nanoparticles are uniformly distributed on the WO3 nanosheets. Energy dispersive element distribution analysis was also performed, as shown in FIG. 2B, which shows uniform distribution of W, O, and Pt elements. In addition, X-ray electron diffraction test was performed on Pt / WO3, and the instrument used was a Rigaku Ultima IV, as shown in FIG. 2C. WO3 corresponds well to the standard card, but there is no obvious Pt peak, which is due to the extremely small amount of Pt. The above test results prove that the prepared sample is tungsten oxide nanosheet supported platinum nanoparticle. Figure 1 Figure 2 Figure 3

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

[0037] (1) 6.597 g of sodium tungstate was dissolved in 20 mL of deionized water, and after complete dissolution, it was added to 180 mL of hydrochloric acid (3 mol / L) and aged for 1 h. Then it was washed with deionized water and anhydrous ethanol for three times by ultrasonic cleaning and centrifugal separation until the filtrate was neutral. The obtained sample was then placed in a vacuum drying oven at 60°C for 12 h, and after complete drying, the sample was ground. Then the sample was placed in a tube furnace with a porcelain boat, calcined at 350°C for 1 h in air atmosphere to obtain tungsten oxide.

[0038] (2) 50 mg of the prepared tungsten oxide powder was weighed, ground and added to 50 mL of deionized water, and ultrasonically dispersed for 10 min, then 80 μL of chloroplatinic acid solution (0.1 g / mL) was added, stirred for 20 min, then the solution was irradiated with a xenon lamp (Polfly PLS-SEX300+, power 300 W) for 8 h. The obtained sample was centrifuged and washed with deionized water for 3 times by ultrasonic cleaning, and finally vacuum dried for 12 h to obtain a tungsten oxide supported platinum catalyst.

[0039] The prepared sample was also confirmed to be tungsten oxide nanosheet supported platinum nanoparticle by transmission electron microscopy, element distribution, and X-ray electron diffraction analysis.

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

[0041] (1) 6.597 g of sodium tungstate was weighed and dissolved in 20 mL of deionized water, and after complete dissolution, it was added to 180 mL of hydrochloric acid (3 mol / L) and aged for 1 h. Then it was washed with deionized water and anhydrous ethanol by ultrasonic for three times and centrifuged until the filtrate was neutral. Then the obtained sample was placed in a vacuum dryer at 60°C for 12 h, and after complete drying, the sample was ground, and then the sample was placed in a tube furnace with a porcelain boat, and calcined at 350°C for 1 h in air to obtain tungsten oxide.

[0042] (2) 50 mg of the prepared tungsten oxide powder was weighed, ground, and added to 50 mL of deionized water, and ultrasonically dispersed for 10 min, and then 100 μL of chloroplatinic acid solution (0.1 g / mL) was added, and stirred for 20 min, and then irradiated with a xenon lamp for 10 h. The obtained sample was centrifuged and washed with deionized water for 3 times, and finally dried in vacuum for 12 h to obtain a tungsten oxide supported platinum catalyst.

[0043] The sample was also confirmed to be tungsten oxide nanosheet supported platinum nanoparticle by transmission electron microscopy, element distribution and X-ray electron diffraction analysis.

[0044] Experimental example: electrochemical test

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

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

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

[0048] Figure 6The overpotential and Tafel slope of Pt / WO3 and commercial Pt / C at 10 mA cm-2are compared in the graph, and it can be seen that the overpotential and Tafel slope of Pt / WO3 are lower than those of commercial Pt / C, indicating that Pt / WO3 has better hydrogen evolution activity and faster catalytic reaction kinetics than commercial Pt / C. -2

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

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

[0051] The embodiments of the present application are described in detail above, but the present application is not limited to the described embodiments. For those skilled in the art, various changes, modifications, replacements and variations of the embodiments can be made without departing from the principles and spirits of the present application, and still fall within the protection scope of the present application.​​​

Claims

1. Use of a photo-reduced tungsten oxide supported platinum catalyst for the hydrogen evolution in the electrolysis of neutral seawater, characterized in that, The method for preparing the tungsten oxide supported platinum catalyst by photoreduction comprises the following steps: S1, dissolving sodium tungstate in water to obtain a sodium tungstate aqueous solution, then adding hydrochloric acid to perform aging treatment, then washing and centrifuging until the filtrate is neutral, drying and grinding the obtained product, and then calcining to obtain tungsten oxide; S2, grinding tungsten oxide powder, dissolving the powder in water to obtain a tungsten oxide aqueous solution, then adding a chloroplatinic acid solution, mixing, and then using a xenon lamp to perform light irradiation treatment on the solution, and then washing and drying the obtained sample to obtain a catalyst in which platinum is supported on tungsten oxide by photoreduction; the concentration of the tungsten oxide powder in water is 5 mg / 4-7 mL, the concentration of the chloroplatinic acid solution is 0.1-0.2 g / mL, and the dosage ratio of the tungsten oxide aqueous solution to the chloroplatinic acid solution is 2-10 mL:2-10 μL.

2. Use 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 the sodium tungstate aqueous solution to the hydrochloric acid is 1:8-10.

3. Use according to claim 1, characterized in that, In S1, the aging treatment is performed for 1-2 h.

4. Use according to claim 1, characterized in that, In S1, the calcination is performed in an air atmosphere, the calcination temperature is 300-400 ℃, and the calcination time is 1-2 h.

5. The use according to claim 1, characterized in that, In S2, the light irradiation time of the xenon lamp is 2-8 h, and the power is 200-400 W.

Images