High-performance Ge and Zr-Fe2O3 photo-anode and preparation method and application thereof

Abstract

The invention relates to a high-performance Ge and Zr-Fe2O3 photo-anode as well as a preparation method and application thereof. According to the preparation method, Ge and Zr elements are introduced into Fe2O3, and the Ge, Zr-Fe2O3 photo-anode film with excellent photoelectrochemical performance is prepared by adopting a hydrothermal method. Ge doping improves the conductivity of Fe2O3, Zr doping improves the crystallinity and corrosion resistance of Fe2O3, and the photoelectrochemical efficiency and stability of Fe2O3 in a water decomposition reaction are remarkably improved through the synergistic effect of Ge doping and Zr doping. The prepared Ge and Zr-Fe2O3 photo-anode material is suitable for solar water decomposition photoelectrochemical reaction, is low in preparation cost and environment-friendly, and has a wide industrial application prospect.

Description

Technical Field

[0001] The present invention belongs to the field of photoelectrochemical technology, and particularly relates to a high-performance Ge, Zr-Fe 2 O 3 photoanode and its preparation method and application. Background Art

[0002] With the increasingly severe energy problem, the conversion of chemical energy using renewable energy (such as solar energy) has become an effective way to solve the energy crisis. As a green technology for converting solar energy into chemical energy, the photoelectrochemical water splitting technology has great application prospects. Fe 2 O 3 has become an ideal photoanode material due to its low cost, non-toxicity, abundant resources and good stability, and is widely used in solar water splitting.

[0003] However, Fe 2 O 3 has low activity in photoelectrochemistry and poor photoconductivity, which limits its application in photoanodes. In addition, Fe 2 O 3 often faces problems of poor stability and easy degradation in practical applications. To solve these problems, researchers have tried to improve the performance of Fe 2 O 3 by doping other elements.

[0004] Geological element (Ge) and transition metal element (Zr) are considered to be able to effectively regulate the electronic structure of Fe 2 O 3 and improve its catalytic performance and stability. Ge doping can enhance the conductivity of Fe 2 O 3 , while Zr doping can enhance the crystallinity and corrosion resistance of Fe 2 O 3 . Therefore, the present invention proposes a Ge, Zr co-doped Fe 2 O 3 photoanode material, aiming to improve the photoelectrochemical performance and long-term stability of Fe 2 O 3 through co-doping. Summary of the Invention

[0005] The present invention provides a high-performance Ge, Zr-Fe 2 O 3 photoanode and its preparation method and application. By reasonably regulating the concentration of Ge and Zr doping and the preparation conditions, an Fe 2 O 3 with excellent catalytic performance, high current density and long-term stability is obtained.Photoanode material. This material has shown significant performance improvement in the solar water splitting reaction.

[0006] To achieve the above object, the present invention adopts the following technical solutions: A high-performance Ge, Zr-Fe 2 O 3 photoanode, and the preparation method includes the following steps:

[0007] 1) Dissolve iron salt and sodium acetate in deionized water, add an ethanol solution of ZrO(NO 3 ) 2 , and stir to obtain a precursor solution; place the precursor solution and FTO conductive glass in a hydrothermal reactor, and through hydrothermal reaction, grow the precursor Zr-FeOOH on the conductive glass FTO to obtain a precursor Zr-FeOOH photoanode film;

[0008] 2) Immerse the Zr-FeOOH photoanode film in an aqueous solution containing GeO 2 to obtain a Ge, Zr-FeOOH photoanode;

[0009] 3) Calcinate Ge, Zr-FeOOH under air conditions to obtain a Ge, Zr-Fe 2 O 3 photoanode film.

[0010] For the above-mentioned high-performance Ge, Zr-Fe 2 O 3 photoanode, in step 1), the iron salt is ferric chloride hexahydrate or ferric sulfate.

[0011] For the above-mentioned high-performance Ge, Zr-Fe 2 O 3 photoanode, in step 1), the concentration of the ethanol solution of ZrO(NO 3 ) 2 is 1 mmol / L.

[0012] For the above-mentioned high-performance Ge, Zr-Fe 2 O 3 photoanode, in step 1), by molar ratio, iron salt: sodium acetate: ZrO(NO 3 ) 2 is 1800:2000:(0.5 - 3).

[0013] For the above-mentioned high-performance Ge, Zr-Fe 2 O 3 photoanode, in step 1), for the hydrothermal reaction, the reaction temperature is 100 °C and the reaction time is 3 h.

[0014] For the above-mentioned high-performance Ge, Zr-Fe2 O 3 Photoanode, in step 2), the GeO 2 concentration of the aqueous solution is 40 mmol / L.

[0015] The above-mentioned high-performance Ge, Zr-Fe 2 O 3 Photoanode, in step 2), the impregnation time is 20 min.

[0016] The above-mentioned high-performance Ge, Zr-Fe 2 O 3 Photoanode, in step 3), the calcination, the calcination temperature is 550 °C, and the time is 2 h.

[0017] The above-mentioned high-performance Ge, Zr-Fe 2 O 3 The photoanode can be applied in photoelectrochemical water splitting for hydrogen production.

[0018] The above application, the method is as follows, using the above-mentioned high-performance Ge, Zr-Fe 2 O 3 Photoanode as the working electrode, a platinum sheet as the counter electrode, Ag / AgCl as the reference electrode, the electrolyte is 1 M potassium hydroxide, and the light source is a 300 W xenon lamp for photocatalytic water splitting to produce hydrogen.

[0019] The beneficial effects of the present invention are:

[0020] 1. The Ge, Zr-Fe 2 O 3 photoanode film provided by the present invention effectively improves the electronic structure and conductivity of Fe 2 O 3 and improves the photoelectrochemical efficiency of the photoanode.

[0021] 2. All the materials used in the preparation method of the Ge, Zr-Fe 2 O 3 photoanode film provided by the present invention are low-cost and environmentally friendly, and the preparation process is simple, having broad industrial application potential.

[0022] 3. The hydrogen production rate of the Ge, Zr-Fe 2 O 3 photoanode film under visible light is about 2.5 times that of Fe 2 O 3 Description of the Drawings

[0023] Figure 1 For the Ge, Zr-Fe prepared in Example 2 2 O 3Photoanode thin film, Example preparation of Ti-Fe 2 O 3 Comparison chart of thin film XRD.

[0024] Figure 2 Ge, Zr-Fe prepared for Example 2 2 O 3 Photoanode thin film, Example preparation of Ti-Fe 2 O 3 Comparison chart of thin film XRD LSV.

[0025] Figure 3 Ge, Zr-Fe prepared for Example 2 2 O 3 Photoanode thin film, Example preparation of Ti-Fe 2 O 3 Water decomposition hydrogen production rate chart of thin film XRD. Detailed implementation method

[0026] (I) Preparation method

[0027] Example 1 Fe 2 O 3 Photoanode thin film

[0028] (I) Preparation method

[0029] Dissolve 0.486 g of ferric chloride hexahydrate and 0.164 g of sodium acetate in 20 mL of deionized water, and stir well to prepare a precursor solution.

[0030] Put the precursor solution and the cleaned FTO conductive glass in a 100 mL hydrothermal autoclave, and perform a hydrothermal reaction at 100 °C for 3 h to obtain a FeOOH photoanode thin film; calcine the FeOOH photoanode thin film at 550 °C for 2 h to obtain Fe 2 O 3 Photoanode thin film.

[0031] Example 2 High-performance Ge, Zr-Fe 2 O 3 Photoanode

[0032] (I) Preparation method

[0033] Dissolve 0.486 g of ferric chloride hexahydrate and 0.164 g of sodium acetate in 20 mL of deionized water, and add 1 ml of ZrO(NO 3 ) 2 ethanol solution, and stir well to prepare a precursor solution. Prepared 0.5 mmol / L, 1 mmol / L, 2 mmol / L and 3 mmol / L ZrO(NO 3 ) 2 ethanol solution.

[0034] The precursor solution and the cleaned FTO conductive glass were placed in a 100 mL hydrothermal autoclave and hydrothermally treated at a set temperature of 100 °C for 2 h, 3 h, and 4 h to obtain Zr-FeOOH thin films.

[0035] The Zr-FeOOH thin films were immersed in an aqueous solution of 40 mmol / L GeO 2 for 10 min, 20 min, 30 min, and 40 min.

[0036] The Ge,Zr-FeOOH thin films were calcined in a muffle furnace at 550 °C for 2 h to obtain Ge,Zr-Fe 2 O 3 photoanode thin films.

[0037] Under certain other conditions, with only one variable present, the optimal reaction conditions were determined by measuring the photocurrent density through LSV tests. The results showed that the optimal concentration of the ZrO(NO 3 ) 2 ethanol solution was 1 mmol / L, the optimal reaction time was 3 h, and the optimal GeO 2 immersion time was 20 min.

[0038] (II) Detection

[0039] Figure 1 XRD comparison charts of the Ge,Zr-FeO 2 photoanode thin films prepared in Example 2 and the FeO 3 thin films prepared in Example 1. As 2 can be seen, the diffraction peaks of Ge,Zr-FeO 3 and FeO Figure 1 corresponded to the diffraction peaks of SnO 2 O 3 (FTO) (PDF#46-1088) and FeO 2 O 3 (PDF#33-0664), respectively. It was proved that the doping did not change the crystal structure of FeO 2 (FTO). However, after doping, the diffraction peaks of FeO 2 O 3 showed a slight shift, proving the successful doping of Ge and Zr. 2 O 3 2 O 3

[0040] Example 4 Application

[0041] The FeO 2 O 3 prepared in Example 1 and Ge,Zr-FeO 2O 3 Perform performance tests such as LSV and water splitting on the photoanode film.

[0042] All electrochemical experiment tests were carried out in an electrochemical workstation (Princeton Applied Research 2273) with a three-electrode system. The sample film was used as the working electrode, a platinum sheet as the counter electrode, Ag / AgCl as the reference electrode, the electrolyte was 1M potassium hydroxide, and the light irradiation area of the sample was 1 cm 2 , and a GC-1690 was used to detect the hydrogen production amount per period of time during the water splitting test.

[0043] LSV test: The light source was a 300W xenon lamp (100mW / cm 2 ), the bias voltage was 1.23V vs. RHE, and the measured results were as Figure 2 shown. The results showed that the photocurrent density of the Ge,Zr-Fe 2 O 3 photoanode was much larger than that of Fe 2 O 3 , indicating that the photoelectrochemical performance was improved after doping.

[0044] Water splitting hydrogen production test: The light source was selected as a 300W xenon lamp (100mW / cm 2 ), the bias voltage was 1.23V vs. RHE, and the measured results were as Figure 3 shown. After doping Ge and Zr, the hydrogen production rate value (26 μmol h 2 O 3 ) of the Fe -1 cm -2 ) photoanode film was greater than that of Fe 2 O 3 (8.4 μmol h -1 cm -2 ), proving that the Ge,Zr-Fe 2 O 3 photoanode film had a more effective water oxidation driving force.

Claims

1. A high-performance Ge, Zr-Fe2O3 photoanode, characterized in that: The preparation method comprises the following steps: 1) dissolving iron salt and sodium acetate in deionized water, adding ZrO(NO3)2 ethanol solution, stirring to obtain a precursor solution; placing the precursor solution and FTO conductive glass in a hydrothermal reactor, growing a precursor Zr-FeOOH on the conductive glass FTO through a hydrothermal reaction, and obtaining a precursor Zr-FeOOH photoanode film; 2) immersing the Zr-FeOOH photoanode film in an aqueous solution containing GeO2 to obtain a Ge, Zr-FeOOH photoanode; 3) Calcine Ge, Zr-FeOOH under air conditions to obtain Ge, Zr-Fe2O3 photoanode film.

2. A high performance Ge, Zr-Fe2O3 photoanode as claimed in claim 1, characterized in that: In step 1), the iron salt is ferric chloride hexahydrate or ferric sulfate.

3. A high performance Ge, Zr-Fe2O3 photoanode as claimed in claim 1, characterized in that: In step 1), the concentration of the ZrO(NO3)2 ethanol solution is 1 mmol / L.

4. A high performance Ge, Zr-Fe2O3 photoanode as claimed in claim 1, characterized in that: In step 1), the molar ratio of iron salt: sodium acetate: ZrO(NO3)2 is 1800:2000:(0.5-3).

5. A high performance Ge, Zr-Fe2O3 photoanode as claimed in claim 1, characterized in that: In step 1), the hydrothermal reaction has a reaction temperature of 100° C. and a reaction time of 3 h.

6. A high performance Ge, Zr-Fe2O3 photoanode as claimed in claim 1, characterized in that: In step 2), the concentration of the GeO2 aqueous solution is 40 mmol / L.

7. A high performance Ge, Zr-Fe2O3 photoanode as claimed in claim 1, characterized in that: In step 2), the immersion time is 20 minutes.

8. A high performance Ge, Zr-Fe2O3 photoanode as claimed in claim 1, characterized in that: In step 3), the calcination temperature is 550° C. and the time is 2 h.

9. The high-performance Ge, Zr-Fe2O3 photoanode described in claim 1 can be used in photoelectrochemical water decomposition to produce hydrogen.

10. The use according to claim 9, characterized in that: The method is as follows: using the high-performance Ge, Zr-Fe2O3 photoanode described in any one of claims 1 to 9 as a working electrode, a platinum sheet as a counter electrode, Ag / AgCl as a reference electrode, an electrolyte of 1M potassium hydroxide, and a light source of 300W xenon lamp to photolyze water for hydrogen evolution.

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