Method for improving catalytic hydrogen production performance by introducing anion vacancy into Au / semiconductor heterostructure through electrochemical treatment

Abstract

The invention relates to a method for improving catalytic hydrogen production performance by introducing anion vacancies into an Au / semiconductor heterostructure through electrochemical treatment, and belongs to the technical field of catalytic energy. According to the method, gold nanoparticles are used and loaded on semiconductor particles through sputtering, finally, electrochemical treatment is carried out on the composite material, anion vacancies are introduced, and a sample (called a Vc-Au / semiconductor) heterostructure obtained after electrochemical treatment is formed. In the electro-catalysis process, local electron enrichment of anion vacancies can promote high catalytic activity of the catalyst in electro-catalysis hydrogen evolution (HER). When different semiconductors are replaced for loading gold nanoparticles and anion vacancies are introduced through electrochemical treatment, obvious HER activity enhancement is shown. The smooth implementation of the invention provides a universal, simple, convenient and efficient strategy for regulating and controlling the efficiency of the electro-catalytic hydrogen production reaction, solves the problems of high temperature and high energy consumption caused by introducing vacancies in a traditional heat treatment mode, and provides greater possibility for industrialization in the field of electro-catalytic hydrogen production.

Description

Technical Field

[0001] The present invention relates to a method for improving the catalytic hydrogen production performance by introducing anion vacancies in an Au / semiconductor heterostructure through electrochemical treatment. Specifically, the present invention induces the formation of anion vacancies by applying a negative bias voltage on the Au / semiconductor heterostructure, thereby significantly enhancing its activity and stability in electrocatalytic hydrogen evolution reaction (HER) and photocatalytic hydrogen evolution reaction. It belongs to the technical field of catalytic energy. Background Art

[0002] Hydrogen energy is regarded as an ideal choice to solve the energy crisis and environmental problems due to its high energy density and zero carbon emission characteristics. At present, electrocatalytic and photocatalytic hydrogen evolution reactions (HER) have attracted much attention because they can directly utilize electrical energy or solar energy to drive water decomposition. Metal-semiconductor heterostructure catalysts (such as Au / TiO2) improve catalytic activity through the interfacial electron effect, but still face challenges such as insufficient charge separation efficiency, limited active sites, and low utilization rate of photothermal effects. The introduction of oxygen vacancies can effectively regulate the electronic structure, provide active sites, and enhance charge transfer, but existing introduction methods such as high-temperature hydrogen reduction, plasma treatment, and chemical reduction methods have problems such as complex processes, high energy consumption, or poor stability, which limit their practical applications.

[0003] Traditional improvement strategies such as noble metal doping, heterostructure construction, and morphology regulation are either costly or have complex preparation processes, and it is difficult to balance performance and practicality. For example, high-temperature treatment is likely to cause catalyst sintering, chemical reduction methods may introduce impurities, and plasma treatment requires high equipment requirements and poor repeatability. In addition, these methods usually only target a single catalytic system and lack universality. Therefore, developing a low-temperature, simple, and universal method for introducing oxygen vacancies has become a key technical problem in improving catalytic hydrogen production performance.

[0004] The present invention solves the above problems by controllably introducing oxygen vacancies at room temperature through electrochemical treatment. This method not only avoids the damage to the catalyst structure caused by high-temperature treatment, but also can simultaneously improve the electrocatalytic and photocatalytic HER activities, and is applicable to a variety of metal-semiconductor heterostructures (such as Au / MoS2, Au / WS2). This innovation provides a new idea for efficient and stable catalytic hydrogen production and has important potential for industrial application. Summary of the Invention

[0005] The technical problem solved by the present invention is: a method for improving the catalytic hydrogen production performance by introducing anion vacancies in an Au / semiconductor heterostructure through electrochemical treatment. The V ec -Au / TiO2 catalyst has an overpotential as low as 0.065 V in the electrocatalytic hydrogen evolution reaction (10 mA cm -2), the catalytic activity is increased by 2.46 times; the hydrogen production rate in the photocatalytic hydrogen evolution reaction reaches 313.17 μmol g -1 h -1 , an increase of 64.6%. The oxygen vacancies introduced by electrochemical treatment can significantly reduce the interfacial charge transfer resistance (from 4779 Ω to 380 Ω); enhance the separation efficiency of photo-generated carriers, increasing the photocurrent density by 85% - 136%; optimize the surface electronic structure of the catalyst, increasing the number of active sites; improve the cyclic stability of the catalyst (the performance remains unchanged during 5 hours of continuous reaction); and realize the generality of this method in various heterostructure systems such as Au / MoS2 and Au / WS2. The V ec -Au / TiO2 catalyst of the present invention has better activity and stability than the currently reported similar catalysts.

[0006] To solve the above technical problems, the technical solution proposed by the present invention is: a method for enhancing the catalytic hydrogen production performance by introducing anion vacancies into the Au / semiconductor heterostructure through electrochemical treatment. Using a three-electrode system, Au / TiO2 is used as the working electrode for electrochemical treatment to form a V ec -Au / TiO2 catalyst system. The specific method is as follows: First, disperse TiO2 powder in an aqueous solution containing Nafion, and form a uniform film on FTO conductive glass by spin coating, and anneal at 80 °C for 1 hour; then deposit Au nanoparticles by ion sputtering (5 mA, 120 s), and anneal at 200 °C for 1 hour to prepare the Au / TiO2 heterostructure; finally, in a 0.5 M H2SO4 electrolyte solution, using Au / TiO2 as the working electrode, a platinum mesh as the counter electrode, and Ag / AgCl as the reference electrode, apply a negative bias voltage of -1.5 V to -3.0 V for 30 - 120 minutes to form V ec -Au / TiO2 catalyst. The electrocatalytic hydrogen evolution test is carried out in a 0.5 M H2SO4 solution, and the photocatalytic hydrogen evolution test is carried out in a 40 mL quartz reactor containing triethanolamine sacrificial agent, using a 300 W xenon lamp as the light source.

[0007] Preferably, the preparation process of the V ec -Au / TiO2 catalyst: Disperse TiO2 powder (50 mg) in an aqueous solution containing Nafion, spin coat it on FTO glass, and anneal at 80 °C for 1 hour. Deposit Au nanoparticles by ion sputtering (5 mA, 120 s), and anneal at 200 °C for 1 hour. Using Au / TiO2 as the working electrode, apply a negative bias voltage of -1.5 V in a 0.5 M H2SO4 electrolyte solution and treat for 120 minutes to form a V ec -Au / TiO2 catalyst rich in oxygen vacancies.

[0008] Preferably, the process of the electrocatalytic hydrogen evolution experiment is: The prepared Ve The c-Au / TiO2 catalyst was used as the working electrode, and a three-electrode system was composed of a platinum mesh counter electrode and an Ag / AgCl reference electrode (placed in a 3M KCl solution), and placed in a 0.5M H2SO4 electrolyte solution. The solution was pre-purged with nitrogen for 30 minutes to remove dissolved oxygen. Linear sweep voltammetry tests were performed using an electrochemical workstation, with a scanning range of 0 to -0.5V (vs. RHE) and a scanning rate of 5mV s -1 ; Chronoamperometry tests were carried out at a constant potential of -0.3V (vs. RHE) for 5 hours to evaluate the stability; all test data were collected in real time through an electrochemical workstation (CHI 760E, Shanghai Chenhua Instrument Co., Ltd.).

[0009] Preferably, the test process of the photocatalytic hydrogen production experiment was as follows: 19 mL of deionized water and 1 mL of triethanolamine (TEOA) were added to a 40 mL quartz reactor. The substrate with the catalyst coating was vertically placed in the reactor, and then the reactor was sealed with a silicone rubber stopper. Before illumination, the system was rigorously degassed with argon purge for 20 minutes to remove dissolved oxygen. Then the reactor was illuminated with a 300W xenon lamp, and a PTFE-coated magnetic stir bar was used to magnetically stir the suspension in the reactor at a speed of 400 rpm. The gaseous products were sampled regularly every 30 minutes and quantified by gas chromatography (GC-9860-5C, AGC).

[0010] Advantages of the present invention:

[0011] 1. Electrochemical treatment can significantly improve the catalytic performance of Au / TiO2. The oxygen vacancies introduced by electrochemical treatment can not only reduce the interfacial charge transfer resistance (from 4779Ω to 380Ω), but also enhance the separation efficiency of photo-generated carriers, increasing the photocurrent density by 85%-136%. In addition, the presence of oxygen vacancies can optimize the surface electronic structure of the catalyst, increase the number of active sites, and improve the stability of the catalyst at the same time.

[0012] 2. The electrochemical treatment method of the present invention is simple to operate and mild in conditions, and can be completed at room temperature, avoiding the damage to the catalyst structure caused by traditional high-temperature treatment. This method provides a new technical route for efficient and stable catalytic hydrogen production and has important industrial application prospects.

[0013] 3. The V ec -Au / TiO2 catalyst prepared by the present invention has an overpotential as low as 0.065V (10mAcm -2 ) in the electrocatalytic hydrogen evolution reaction, and the catalytic activity is increased by 2.46 times; the hydrogen production rate reaches 313.17μmol g -1 h -1, an increase of 64.6%. The performance of this catalyst remained stable after 5 hours of continuous reaction, significantly superior to the untreated Au / TiO2 catalyst.

[0014] 4. The method has strong generality and can be applied to various metal-semiconductor heterostructure systems such as Au / MoS2, Au / WS2, Au / TiN, etc. The overpotential of electrocatalytic HER is reduced by 3%-17%, showing good universality. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] The present invention will be further described below in conjunction with the accompanying drawings.

[0016] Figure 1 It is a schematic diagram of introducing anion vacancies by electrochemical treatment.

[0017] Figure 2 It is V ec - Structural characterization of Au / TiO2. (a) SEM image of V ec - Au / TiO2. (b) TEM image of V ec - Au / TiO2. (c) XRD patterns of Au / TiO2 and V ec - Au / TiO2. (d) XPS spectrum of the O 1s orbital of V ec - Au / TiO2. (e) XPS spectrum of the Ti 2p orbital of V ec - Au / TiO2. (f) XPS spectrum of the Au 4f orbital of V ec - Au / TiO2

[0018] Figure 3 It is V ec - Electrochemical hydrogen evolution stability curve of Au / TiO2.

[0019] Figure 4 It is the electrocatalytic hydrogen production performance before and after introducing oxygen vacancies by electrochemical treatment after loading gold nanoparticles on different semiconductor catalysts.

[0020] Figure 5 It is (a) LSV curves of V ec - Au / TiO2 samples treated with different voltages. (b) Output current density of V ec - Au / TiO2 samples treated at different voltages, potential is -0.2V vs. RHE. (c) LSV curves of V ec - Au / TiO2 samples at different times. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0021] Example 1

[0022] First, disperse 50 mg of TiO2 powder in 25 mL of an aqueous solution containing 40 μL of Nafion. A uniform thin film is formed on an FTO conductive glass (0.5×1.5 cm 2 ) by spin coating at 3000 rpm for 30 s and annealing at 80 °C for 1 h. Subsequently, Au nanoparticles are deposited by ion sputtering (5 mA, 120 s), and an Au / TiO2 heterostructure is prepared by annealing at 200 °C for 1 h. During the electrochemical treatment process, the prepared Au / TiO2 is used as the working electrode, a platinum mesh is used as the counter electrode, and Ag / AgCl is used as the reference electrode. A negative bias voltage of -1.5 V is applied in a 0.5 M H2SO4 electrolyte for 120 min to obtain the oxygen vacancy-rich V ec -Au / TiO2 catalyst.

[0023] Our electrocatalytic hydrogen evolution experiment process is as follows:

[0024] Take the above-prepared V ec -Au / TiO2 as the working electrode and place it in a 0.5 M H2SO4 electrolyte. The solution is pre-purged with nitrogen for 30 min to remove dissolved oxygen. Linear sweep voltammetry tests are performed using an electrochemical workstation, with a scanning range of 0 to -0.5 V (vs. RHE) and a scanning rate of 5 mV s -1 ; Chronoamperometry tests are carried out at a constant potential of -0.3 V (vs. RHE) for 5 h to evaluate the stability. All test data are collected in real time through an electrochemical workstation (CHI 760E, Shanghai Chenhua Instrument Co., Ltd.).

[0025] As Figure 1 shown in ec is a schematic diagram of the enhanced HER of V

[0026] -Au / TiO2. The anion vacancies enhance the HER performance of Au / TiO2 by synergistically improving the charge transfer efficiency and increasing the active sites. Figure 2 shown in ec is the structural characterization of V

[0027] -Au / TiO2. Scanning electron microscope (SEM) images show that Au nanoparticles are uniformly distributed on the surface of TiO2. X-ray photoelectron spectroscopy (XPS) analysis shows that an obvious oxygen vacancy characteristic peak appears at 532.1 eV in the O1s spectrum of TiO2 after treatment, and the Ti 2p spectrum shifts 0.3 eV towards lower binding energy, confirming the successful introduction of oxygen vacancies. The Au 4f spectrum also shows an increase in binding energy of 0.2 eV, indicating the existence of charge transfer between Au and TiO2. Figure 3 shown, after 5 h of continuous electrocatalytic reaction, V ecThe current density of -Au / TiO2 remains at 30 mA cm -2 , and the performance shows no obvious attenuation. This verifies the promoting effect of oxygen vacancies on the stability of the catalyst.

[0028] Comparative Example 1

[0029] Electrochemical treatment of Au / TiO2 can introduce a high density of oxygen vacancies, thereby enhancing the hydrogen evolution reaction (HER) performance. In theory, this strategy can also be used to introduce vacancies in various other catalysts. As Figure 4 shown, we used the same electrochemical method to treat Au / MoO3, Au / WS2, Au / TiN, and Au / MoS2 heterostructures to introduce vacancies. The LSV curves show that the output current increases significantly after electrochemical treatment. Compared with the original catalyst, the overpotential of the treated Au / MoS2 catalyst at a current density of 10 mA cm -2 decreases by 3 - 17%, indicating that the introduction of vacancies significantly improves the HER performance. In addition, the Tafel slope of the treated Au / MoS2 is 89.63 mV dec -1 , which is significantly lower than 96.30 mV dec -1 of the original catalyst, double-verifying the effectiveness of electrochemical treatment in enhancing the catalytic performance. Similar experimental results are also observed in Au / MoO3, Au / WS2, and Au / TiN samples containing oxygen, sulfur, and nitrogen atoms respectively. These results demonstrate that our electrochemical treatment strategy can improve the activity of different catalysts by introducing various vacancies.

[0030] Comparative Example 2

[0031] Since the electrochemical treatment parameters have an important influence on the oxygen vacancy concentration, we systematically studied the effects of treatment voltage and time on the catalytic performance. As Figure 5 shown, the treatment voltage range of -1.5 V to -3.0 V and the treatment time of 30 - 120 minutes were selected for comparative experiments. The results show that when the voltage is lower than -2.0 V, although the oxygen vacancy concentration increases, it will cause the catalyst to peel off from the substrate; after the treatment time exceeds 120 minutes, the improvement of the catalytic performance tends to saturate. The optimal conditions are determined to be treatment at -1.5 V for 120 minutes, at which time the best balance between catalytic activity and stability is obtained. For the untreated Au / TiO2 under the same test conditions, the overpotential at 10 mA cm -2 is 0.118 V, while that of the optimized-treated V e c-Au / TiO2 drops to 0.065 V, and the activity is increased by 2.46 times. This result verifies the key role of optimizing the electrochemical treatment parameters in enhancing the catalyst performance.

[0032] The present invention is not limited to the specific technical solutions described in the above embodiments, and all technical solutions formed by equivalent substitution are within the protection scope claimed by the present invention.

Claims

1. A method for improving the catalytic hydrogen production performance by introducing anion vacancies in an Au / semiconductor heterostructure through electrochemical treatment, characterized in that : Gold nanoparticles are loaded on the surface of semiconductor particles by a sputtering apparatus to form a composite material catalyst, and oxygen vacancies are introduced through electrochemical treatment to form an electrocatalytic system. Under an additional potential, the method for introducing gold nanoparticles-oxygen vacancies into the semiconductor catalyst to promote the electrocatalyst to catalyze efficient hydrogen production reaction is as follows: the semiconductor particles are dispersed in an aqueous solution and suspended on a conductive glass. After being fully dried, they are placed on the sputtering apparatus stage and gold nanoparticles are sputtered on their surface. Thereafter, the electrodes are electrochemically treated in an electrochemical workstation under a three-electrode system to form a semiconductor composite material with oxygen vacancies and loaded with gold nanoparticles. The electrocatalytic hydrogen production experiment is carried out in a three-electrode system using an additional potential of the electrochemical workstation.

2. The method for improving the catalytic hydrogen production performance by introducing anion vacancies in the Au / semiconductor heterostructure through electrochemical treatment according to claim 1, characterized in that: The electrode coated with a semiconductor catalyst was sputtered with gold nanoparticles at a current of 5 mA for 120 s, and then a cathode potential was applied using an electrochemical workstation to introduce oxygen vacancies. The reaction was carried out in a three-electrode system.

3. The method for improving the catalytic hydrogen production performance by introducing anion vacancies in the Au / semiconductor heterostructure through electrochemical treatment according to claim 1, wherein: Anion vacancies were introduced via electrochemical treatment.

4. The method for improving the catalytic hydrogen production performance by introducing anion vacancies in the Au / semiconductor heterostructure through electrochemical treatment according to claim 1, characterized in that: The specific method of introducing anion vacancies by sputtering gold nanoparticles and then electrochemically treating them is as follows: first, 0.16 mg of semiconductor is suspended on the FTO surface to prepare an electrode, then the electrode is placed on the sputtering stage and gold nanoparticles are sputtered for 120 seconds at a current of 5 mA, then the electrode is kept at 200°C for 1 hour to improve the binding force between gold and semiconductor, and then the electrode is electrochemically treated in a three-electrode system using an electrochemical workstation to introduce anion vacancies.

5. The method for improving the catalytic hydrogen production performance by introducing anion vacancies in the Au / semiconductor heterostructure through electrochemical treatment according to claim 1, characterized in that: The semiconductor is TiO2, MoS2, MoO3 or TiN.

6. The method for improving the catalytic hydrogen production performance by introducing anion vacancies in the Au / semiconductor heterostructure through electrochemical treatment according to claim 1, characterized in that: The experimental process of electrocatalytic hydrogen production is as follows: the catalytic electrode prepared above is installed in a three-electrode electrolytic cell containing 50ml of 0.5M H2SO4 solution, and a cathode potential is gradually applied to it at 0.05mV / s using an electrochemical workstation. After the results are derived, its performance is calculated.

Images