A gold and platinum bimetal-modified tungsten trioxide photoanode, a preparation method and application thereof

Abstract

The application discloses a gold and platinum bimetal modified tungsten trioxide photoanode and a preparation method and application thereof, and comprises the following steps: 1) dropping and casting an ammonium metatungstate solution on a conductive substrate, drying, calcining, and obtaining a tungsten trioxide photoanode; 2) immersing the tungsten trioxide photoanode obtained in the step 1) in a solution containing gold ions and platinum ions first, and then immersing the tungsten trioxide photoanode in a hydrazine hydrate solution after drying, so as to obtain a gold and platinum bimetal modified tungsten trioxide photoanode. The high-efficiency photoanode is prepared through the simple, environment-friendly and economical preparation method, the photoanode has higher photocatalytic activity, has high solar utilization rate, has a better application prospect in the aspect of photoelectrocatalytic decomposition of water, and provides a new method for a green hydrogen energy production process.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of photoelectrocatalysis, and particularly relates to a tungsten trioxide photoanode modified by gold and platinum bimetal and a preparation method and application thereof. BACKGROUND

[0002] Photoelectrocatalytic water splitting is a very promising means to solve energy and environmental problems and is a challenging research direction in the field of energy.

[0003] Photoelectrocatalysis is a new energy-saving and environment-friendly technology, which refers to the conversion of light energy into chemical reaction energy under a certain voltage, thereby producing a catalytic effect. The most concerned is the photocatalytic decomposition of water by using solar energy. Since the pioneering work of Inoue et al., many studies have been devoted to the photocatalytic / photoelectrocatalytic decomposition of water by using semiconductors such as TiO2. However, due to the large band gap of TiO2 (about 3.2 eV), only about 4% of the ultraviolet light energy in sunlight can be utilized, which limits its application in the field of photocatalysis / photoelectrocatalysis.

[0004] Tungsten trioxide is a visible light semiconductor catalyst that has attracted widespread attention due to its non-toxicity, low cost, and high stability. The photoanode prepared by using tungsten trioxide has also gained more and more research in the field of photoelectrocatalysis. Although tungsten trioxide has good visible light absorption properties, it has defects such as small specific surface area, narrow energy band structure, and easy recombination of photo-generated holes and electrons, which leads to low actual quantum efficiency and low photoelectrocatalytic activity. Therefore, many methods including noble metal deposition, semiconductor compounding, metal ion and non-metal ion doping have been used to modify tungsten trioxide, but the effect is still not ideal. Therefore, it is still an important research direction to develop a simple and high-catalytic-activity photoanode. SUMMARY

[0005] In view of the defects of the tungsten trioxide photoanode in the prior art, the purpose of the present application is to provide a simple and high-catalytic-activity tungsten trioxide photoanode modified by gold and platinum bimetal and a preparation method and application thereof.

[0006] To achieve the above technical purpose, the present application provides the following technical solutions:

[0007] The preparation method of the tungsten trioxide photoanode modified by gold and platinum bimetal provided by the present application comprises the following steps:

[0008] 1) Drop-casting an ammonium metatungstate solution on a conductive substrate, drying, and calcining to obtain a tungsten trioxide photoanode;

[0009] 2) the tungsten trioxide photoanode obtained in step 1) is first immersed in a solution containing gold ions and platinum ions, dried, and then immersed in a hydrazine hydrate solution to obtain a tungsten trioxide photoanode modified with gold and platinum bimetal.

[0010] Preferably, in step 1), the concentration of the ammonium metatungstate solution is 0.05-0.5 g / mL, and the conductive substrate is FTO or ITO.

[0011] Preferably, in step 1), the calcination temperature is 300-600°C, and the calcination time is 1-8 h.

[0012] Preferably, in step 2), in the solution containing gold ions and platinum ions, the gold-containing substance is chloroauric acid or sodium chloroaurate, and the platinum-containing substance is any one of chloroplatinic acid, sodium chloroplatinate, and potassium chloroplatinate.

[0013] Preferably, in step 2), in the solution containing gold ions and platinum ions, the concentration of gold ions is 5-25 mmol / L, and the concentration of platinum ions is 5-25 mmol / L.

[0014] Preferably, in step 2), the tungsten trioxide photoanode is immersed in the solution containing gold ions and platinum ions for 1-5 h, and in the hydrazine hydrate solution for 5-30 min.

[0015] Preferably, in step 2), the concentration of the hydrazine hydrate solution is 0.1%-1%.

[0016] The tungsten trioxide photoanode modified with gold and platinum bimetal is prepared according to the preparation method.

[0017] In the tungsten trioxide photoanode modified with gold and platinum bimetal, the molar percentage content of gold and platinum loaded is 0.5%-5% relative to the photoanode, respectively.

[0018] The tungsten trioxide photoanode modified with gold and platinum bimetal can increase the light response range and improve the separation efficiency of photo-generated electron-hole pairs by utilizing the catalytic synergy of gold and platinum bimetal, thereby improving the photoelectrocatalytic performance.

[0019] The application provides the use of the tungsten trioxide photoanode modified with gold and platinum bimetal in the photoelectrocatalytic decomposition of water, which comprises the following steps: using the tungsten trioxide photoanode modified with gold and platinum bimetal as a photoanode, using a platinum electrode as a cathode, and assembling a photoelectrolytic cell together with an electrolyte, so that water is oxidized to oxygen on the photoanode and reduced to hydrogen on the cathode under light intensity and bias.

[0020] Preferably, the electrolyte is a sodium sulfate solution, the mass concentration of the electrolyte is 0.1-100 g / L, and the light intensity is 100-500 mW·cm.-2 The bias is 0-3V.

[0021] Compared with the prior art, the technical scheme of the present application has the beneficial effects that:

[0022] 1. The gold and platinum bimetal modified tungsten trioxide photoanode of the present application is formed by in-situ reduction of gold and platinum on the surface of tungsten trioxide. The catalytic effect of the bimetal and the synergistic effect of the two are significantly enhanced. Gold and platinum nanoparticles act as charge acceptors, improving the separation and transfer efficiency of photo-generated electrons and holes, thereby improving the photoelectrocatalytic performance of the photoanode. The synthesized photoanode has important practical application value in photoelectrocatalytic reactions.

[0023] 2. The technical scheme of the present application can deposit gold and platinum on the surface of tungsten trioxide by simple and mild solution treatment, and can realize the regulation of the content of gold and platinum nanoparticles by regulating the solution concentration and immersion time.

[0024] 3. The gold and platinum bimetal modified tungsten trioxide photoanode of the present application has higher photocatalytic activity than the original tungsten trioxide photocatalyst in photoelectrocatalytic water splitting, has high solar energy utilization rate, and has better application prospect in photoelectrocatalytic water splitting.

[0025] The present application provides a simple, environmentally friendly and economical preparation method for preparing a high-efficiency photoanode, which solves the problems of low light absorption efficiency and low photoelectrocatalytic activity in existing photoelectrocatalytic water splitting, reduces the dependence on fossil resources, and develops a green hydrogen energy production process. BRIEF DESCRIPTION OF DRAWINGS

[0026] Figure 1 is a schematic diagram of the photoelectrocatalytic water splitting reaction of the present application;

[0027] Figure 2 is a scanning electron microscope image of the photoanode in Example 1 of the present application;

[0028] Figure 3 is the hydrogen and oxygen generation rate of the photoelectrocatalytic reaction in Example 1 of the present application. DETAILED DESCRIPTION

[0029] The technical scheme of the present application will be further described below through specific examples, but the protection scope of the present application is not limited to the following examples.

[0030] Example 1

[0031] Ammonium metatungstate (0.05 g / mL) was drop-cast onto FTO, dried, and calcined at 500 °C for 2 h to obtain a tungsten trioxide photoanode. This tungsten trioxide photoanode was then immersed in a solution containing 10 mmol / L chloroauric acid and 5 mmol / L chloroplatinic acid for 2 h, dried, and finally immersed in a 0.6% hydrazine hydrate solution for 10 min to obtain a gold-platinum bimetallic modified tungsten trioxide photoanode. A scanning electron microscope image of the gold-platinum bimetallic modified tungsten trioxide photoanode is shown below. Figure 2 As shown, the pomegranate-shaped tungsten trioxide microspheres are interconnected.

[0032] Application Example 1

[0033] Using the gold and platinum bimetallic modified tungsten trioxide photoanode prepared in Example 1 as the photoanode and a platinum sheet as the cathode, an electrolytic cell was assembled using 71 g / L sodium sulfate solution as the electrolyte. The electrolytic cell was then subjected to AM 1.5G illumination (100 mW·cm⁻¹). -2 The reaction proceeded for 3 hours under a bias voltage of 1.23V. A schematic diagram of the reaction apparatus is shown below. Figure 1 As shown.

[0034] The photoelectrocatalytic products were detected by gas chromatography, and the results are as follows: Figure 3 As shown, the gold and platinum bimetallic modified tungsten trioxide photoanode has three times the photoelectrocatalytic efficiency of the simple tungsten trioxide photoanode.

[0035] Example 2

[0036] Ammonium metatungstate at a concentration of 0.1 g / mL was drop-cast onto FTO, dried, and calcined at 300 °C for 1 h to obtain a tungsten trioxide photoanode. This tungsten trioxide photoanode was then immersed in a solution containing 10 mmol / L sodium chloroaurate and 10 mmol / L sodium chloroplatinate for 1 h, dried, and then immersed in a 1% hydrazine hydrate solution for 5 min to obtain a gold-platinum bimetallic modified tungsten trioxide photoanode.

[0037] Application Example 2

[0038] Using the gold and platinum bimetallic modified tungsten trioxide photoanode prepared in Example 2 as the photoanode and a platinum sheet as the cathode, an electrolytic cell was assembled using a 0.1 g / L sodium sulfate solution as the electrolyte. The cell was then subjected to AM 1.5G illumination (300 mW·cm⁻¹). -2 The reaction was carried out at a bias voltage of 0.5V for 3 hours.

[0039] The photoelectrocatalytic product was detected by gas chromatography, and its photoelectrocatalytic hydrogen production rate was 2.3 μmol / cm³. -2 h -1 The oxygen production rate was 1.15 μmol / cm³. -2 h -1 .

[0040] Example 3

[0041] Ammonium metatungstate at a concentration of 0.5 g / mL was drop-cast onto ITO, dried, and calcined at 600 °C for 8 h to obtain a tungsten trioxide photoanode. This tungsten trioxide photoanode was then immersed in a solution containing 25 mmol / L chloroauric acid and 25 mmol / L potassium chloroplatinate for 5 h, dried, and then immersed in a 1% hydrazine hydrate solution for 30 min to obtain a gold-platinum bimetallic modified tungsten trioxide photoanode.

[0042] Application Example 3

[0043] Using the gold and platinum bimetallic modified tungsten trioxide photoanode prepared in Example 3 as the photoanode and a platinum sheet as the cathode, an electrolytic cell was assembled using a 100 g / L sodium sulfate solution as the electrolyte. The electrolytic cell was then subjected to AM 1.5G illumination (500 mW·cm⁻¹). -2 The reaction was carried out for 3 hours under a 2V bias voltage.

[0044] The photoelectrocatalytic product was detected by gas chromatography, and its photoelectrocatalytic hydrogen production rate was 8.5 μmol / cm³. -2 h -1 The oxygen production rate was 4.25 μmol / cm³. -2 h -1 .

[0045] Through the above examples, the applicant has illustrated the preparation method and photoelectrocatalytic water splitting performance of the gold and platinum bimetallic modified tungsten trioxide photoanode. The above descriptions are merely preferred embodiments of the present invention, and the scope of protection of the present invention is not limited to the above-described embodiments. All equivalent variations and modifications made within the scope of the claims of this application should be considered within the scope of the present invention. The scope of protection claimed in this application is as shown in the claims.

Claims

1. A method for preparing a gold-platinum bimetallic modified tungsten trioxide photoanode, comprising the following steps: 1) A solution of ammonium metatungstate is drop-cast onto a conductive substrate, dried, and calcined to obtain a tungsten trioxide photoanode; 2) The tungsten trioxide photoanode obtained in step 1) is first immersed in a solution containing gold ions and platinum ions, dried, and then immersed in a hydrazine hydrate solution to obtain a gold and platinum bimetallic modified tungsten trioxide photoanode. In step 1), the concentration of ammonium metatungstate solution is 0.05~0.5g / mL, the conductive substrate is FTO or ITO; the calcination temperature is 300~600℃, and the calcination time is 1~8h. In step 2), the tungsten trioxide photoanode is immersed in a solution containing gold and platinum ions for 1-5 hours and in a hydrazine hydrate solution for 5-30 minutes; the concentration of the hydrazine hydrate solution is 0.1%-1%; in the solution containing gold and platinum ions, the concentration of gold ions is 5-25 mmol / L and the concentration of platinum ions is 5-25 mmol / L.

2. The method for preparing the gold and platinum bimetallic modified tungsten trioxide photoanode according to claim 1, characterized in that, In step 2), the solution containing gold ions and platinum ions contains gold-containing substances that are chloroauric acid or sodium chloroaurate, and platinum-containing substances that are any one of chloroplatinic acid, sodium chloroplatate, and potassium chloroplatate.

3. A gold and platinum bimetallic modified tungsten trioxide photoanode prepared by the preparation method described in claim 1 or 2.

4. An application of the gold and platinum bimetallic modified tungsten trioxide photoanode as described in claim 3 in photoelectrocatalytic water splitting, comprising the following steps: using the gold and platinum bimetallic modified tungsten trioxide photoanode as the photoanode and the platinum electrode as the cathode, assembling them together with the electrolyte to form a photoelectrolysis cell, wherein under light intensity and bias voltage, water is oxidized to oxygen at the photoanode and reduced to hydrogen at the cathode.

5. The application according to claim 4, characterized in that, The electrolyte is a sodium sulfate solution with a mass concentration of 0.1–100 g / L and a light intensity of 100–500 mW·cm. -2 The bias voltage is 0.5 to 2V.

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