CN111020501A

CN111020501A - Preparation method of copper bismuthate film

Info

Publication number: CN111020501A
Application number: CN201911192917.5A
Authority: CN
Inventors: 冯柯; 埃泽尔·阿金诺古; 博热耶夫·法拉比; 薛亚飞; 金名亮; 王新; 周国富; 迈克尔·诺顿; 米夏埃尔·吉尔斯西
Original assignee: Zhaoqing South China Normal University Optoelectronics Industry Research Institute
Current assignee: Zhaoqing South China Normal University Optoelectronics Industry Research Institute
Priority date: 2019-11-28
Filing date: 2019-11-28
Publication date: 2020-04-17
Also published as: WO2021103478A1

Abstract

The invention belongs to the technical field of photoelectrode materials, and particularly relates to a preparation method of a copper bismuthate film, which utilizes a magnetron sputtering method to prepare the copper bismuthate film with the vacuum degree of 4-8 x10^‑4Introducing mixed gas of oxygen and argon into a Pa reaction cavity, respectively applying 5-40w of power to a copper target and 15w of power to a bismuth target through a radio frequency direct current power supply to form plasma, wherein the partial pressure of the argon is 0.75-0.85 Pa, and O is₂The partial pressure is 0.15-0.25 Pa, the deposition time is 10-20 min, and annealing is carried out in air for 15-25 min at 550-650 ℃ after deposition is finished. The preparation method is simple, and the obtained film has flat surfaceThe density is high, and the method is very beneficial to preparing the film with large coverage area, so the method can be widely used for industrial production. According to the invention, the structural composition and the optical band gap of the thin film are changed by applying power to the target material, so that a material with a proper band gap is obtained. The method is also suitable for preparing other ternary metal oxides by a magnetron sputtering method.

Description

Preparation method of copper bismuthate film

Technical Field

The invention belongs to the technical field of photoelectrode materials, and particularly relates to a preparation method of a copper bismuthate film.

Background

With the development of the human society industry, environmental problems become more serious. TiO has been reported since 1972 in Takao and Honda₂Photocatalysis has been considered one of the most effective and economical approaches to environmental problems since the evolution of oxygen and hydrogen under light exposure to electrodes. The destruction of organic contaminants by semiconductor photocatalytic processes has attracted considerable attention over the last two decades due to the complete breakdown of organic contaminants. Among these semiconductors, oxides of titanium (Ti), bismuth (Bi), zinc (Zn), and tin (Sn) are preferred materials for photocatalytic processes.

The development of sustainable, renewable and portable clean energy for replacing fossil fuels is an energy problem to be solved urgently today. Hydrogen (H)₂) Is always a clean energy source with great concern. The heat energy of hydrogen energy is 120 MJ.Kg-1, which is almost three times of gasoline. The production of hydrogen by Photoelectrochemical (PEC) water splitting technology, known as "artificial photosynthesis", which uses solar energy to irradiate an electrolyte device immersed in water to produce hydrogen and oxygen, is an ideal renewable deviceA raw energy production form. To achieve large-scale decomposition of PEC water, new materials must be developed. These materials must be composed of abundant elements, remain stable in aqueous solutions under light, and efficiently drive the water splitting half-reactions (oxygen evolution reaction (OER) and Hydrogen Evolution Reaction (HER)). In PEC water splitting systems, the hydrogen evolution reaction occurs on the photocathode of a p-type semiconductor.

Metal oxides have become attractive materials for photoelectrodes, such as TiO, due to their ability to provide different bandwidths and generally better stability₂，WO₃，Fe₂O₃， BiVO₄And the like. Although many complex metal oxide materials have been identified as potential semiconductor candidates for photoelectrodes that can be used in the water splitting of PECs, the art is still limited by poorly understood materials. Alternative metal oxides with higher theoretical maximum photocurrent densities are urgently needed and their development is crucial to achieving high efficiencies.

Recently, ternary oxides have attracted a great deal of attention in hydrogen evolution reactions, such as CuBi₂O₄(copper bismuthate) which was first proposed in 2007 as a material for hydrogen evolution reactions. The optical band gap is 1.5-1.8eV, the initial potential of photocurrent is 1VRHE, and the maximum photocurrent can reach 19.7-29.0mA cm under AM1.5 illumination^-2Due to CuBi₂O₄(copper bismuthate) exhibits very attractive photoelectrochemical properties and has not been reported to date to exhibit photocurrent densities approaching the limiting theory, and thus has also been the focus of recent research. And, since CuBi₂O₄The surface special catalytic property and optical property, especially the light absorption in visible light region, can be used as a novel photocatalytic material and can also be used for photodegrading organic matters.

Disclosure of Invention

The invention provides a preparation method of a copper bismuthate film. The invention adopts the magnetron sputtering method to prepare the copper bismuthate film, the magnetron sputtering method is a commonly used method for preparing metal and metal oxide films, the film prepared by the magnetron sputtering method has the characteristics of compactness and uniformity, and the magnetron sputtering can be widely applied toCommercial, therefore, the present invention proposes for the first time the preparation of CuBi by magnetron sputtering₂O₄The (copper bismuthate) film is used as a cathode for photo-hydrolysis to produce hydrogen.

In order to achieve the purpose, the invention adopts the technical scheme that:

a preparation method of a copper bismuthate film utilizes a magnetron sputtering method, and the vacuum degree is 4-8 x10^-4Introducing mixed gas of oxygen and argon into a Pa reaction cavity, respectively applying 5-40w of power to a copper target and 15w of power to a bismuth target through a radio frequency direct current power supply to form plasma, wherein the partial pressure of the argon is 0.75-0.85 Pa, and O is₂The partial pressure is 0.15-0.25 Pa, the deposition time is 10-20 min, and annealing is carried out in air for 15-25 min at 550-650 ℃ after deposition is finished.

Preferably, before the film is deposited, the vacuum degree of the magnetron sputtering reaction cavity is pumped to 4-8 x10^-4Pa. Introducing 8sccm O into the reaction chamber at room temperature₂And 40sccm Ar gas, the partial pressure of oxygen in the reaction chamber is controlled to be 0.2Pa, and the partial pressure of Ar is controlled to be 0.8Pa, as shown in figure 1, so that plasma is formed in front of the target and deposited on a rotating sample table for containing the FTO and the n-type silicon wafer. The composition and thickness of the film are changed by applying different powers to the copper and bismuth targets and controlling the deposition time, thereby changing various properties of the film.

More preferably, annealing is carried out at 600 ℃ for 20 minutes in air.

The invention simultaneously protects a preparation method for adjusting the structural composition and the optical band gap in the ternary metal oxide, which comprises the following steps: using magnetron sputtering method, and making the vacuum degree be 4-8 x10^-4And introducing mixed gas of oxygen and argon into the Pa reaction cavity, applying power to corresponding metal targets through a radio frequency direct current power supply respectively to form plasma and deposit, and annealing in the air at 400-800 ℃ after the deposition is finished.

Compared with the prior art, the invention has the beneficial effects that:

the key point of the invention is that the CuBi is prepared by magnetron sputtering₂O₄(copper bismuthate) film and by varying the power applied to the two targets during the preparation of the filmThe structural composition of the film is changed, so that the optical band gap of the film is changed, and the band gap of the film can be adjusted by simply changing the power of the target material, so that the material with the appropriate band gap can be obtained. The preparation method is simple, the obtained film has smooth surface and high density, and the method is very favorable for preparing the film with large coverage area and can be widely used for industrial production. The invention changes the structural composition and the optical band gap of the film by simply changing the power applied to the target material, thereby obtaining the material with proper band gap. The method is also suitable for preparing other ternary metal oxides by a magnetron sputtering method, and the structural composition and the size of the optical band gap of the material can be changed by simply changing the power applied to the target material, so that the band gap of the material can be adjusted to a proper size.

Drawings

FIG. 1 is a schematic view of film deposition;

FIG. 2 XRD patterns of copper target power from 5w to 40w when bismuth target power is fixed at 15 w;

FIG. 3 is a graph showing the variation of optical band gap with power for films prepared at different copper powers.

FIG. 4 is a Scanning Electron Microscope (SEM) picture of the surface of a copper bismuthate thin film prepared by different methods: (a) sol-gel method, (b) spin coating method, (c) electrochemical deposition method, and (d) DC magnetron sputtering method.

Detailed Description

The following further describes the embodiments of the present invention. It should be noted that the description of the embodiments is provided to help understanding of the present invention, but the present invention is not limited thereto. In addition, the technical features involved in the embodiments of the present invention described below may be combined with each other as long as they do not conflict with each other.

Before the film is deposited, the vacuum degree of a magnetron sputtering reaction cavity is pumped to 4-8 x10^-4Pa. Introducing 8sccm O into the reaction chamber at room temperature₂And 40sccm Ar gas, the partial pressure of oxygen in the reaction chamber is controlled to be 0.2Pa, the partial pressure of Ar is controlled to be 0.8Pa, and plasma is formed in front of the target and deposited on the targetAnd a rotating sample table for holding FTO and n-type silicon wafers. FIG. 1 is a schematic view of film deposition. The composition and thickness of the film are changed by applying different powers to the copper and bismuth targets and controlling the deposition time, thereby changing various properties of the film.

In order to research the influence of the power applied to the target material on the material composition structure, the power applied to the Bi target is fixed at 15w, the power of 5-40w is applied to the copper target, films with different copper and bismuth contents are obtained by continuous deposition for 15min, and then the films prepared by magnetron sputtering are annealed for 20min at 600 ℃ in a tube furnace. Fig. 2 is an XRD spectrum of the prepared thin film with a change in copper power when the sputtering power of the bismuth target is constant. As can be seen from the figure, CuBi is shown in all the films₂O₄Characteristic peak of (copper bismuthate), which shows that CuBi can be obtained by magnetron sputtering method and annealing at 600 ℃ for 20min under the condition of air₂O₄A film. With increasing copper power, CuBi₂O₄The characteristic peak of CuO becomes more and more pronounced, and when the copper power is increased to 20w, the characteristic peak of CuO also appears.

Due to the change of the sputtering power of the copper target, when the power of the copper target is changed and the deposition temperature, time, pressure and power of the bismuth target are fixed, the composition of the prepared film is changed, and the optical band gap of the semiconductor material is changed. Figure 3 is a graph showing the change in optical bandgap of the film with copper power. When the copper power is 5w, the bandwidth of the film is 1.82eV, the optical band gap of the obtained film is reduced along with the increase of the copper power, and when the copper power is increased to 40w, the optical band gap of the film is reduced to 1.36 eV. The copper bismuthate film is prepared by a magnetron sputtering method, and the optical band gap of the film can be adjusted by simply changing the power of a target material.

The invention prepares CuBi by magnetron sputtering₂O₄The (copper bismuthate) film is prepared, the structural composition of the film is changed by changing the power applied to the two targets during the preparation of the film, so that the optical band gap of the film is changed, and the band gap of the film can be adjusted by simply changing the power of the targets to obtain the film with proper band gapThe material of (1).

The preparation method is simple, the obtained film has smooth surface and high density, and the method is very beneficial to preparing the film with large coverage area, so the method can be widely used for industrial production. And the structural composition and the optical band gap of the thin film can be changed by simply changing the power applied to the target, so that the material with the appropriate band gap can be obtained.

A suitable optical bandgap is important for semiconductor materials. By the method, the material composition can be changed by simply changing the power, so that the optical band gap of the material is changed, and the material with the proper band gap is obtained for photo-hydrolysis and CO₂Reduction, photovoltaic devices, optical sensors, photocatalytic degradation of organic matter, and the like.

And the film prepared by the method has smooth surface and high density, which is very important for materials used for photocatalysis.

The invention respectively adopts other methods such as: spin coating, sol-gel, electrochemical deposition and other methods are used for preparing the film, and the density and smoothness of the film are verified.

The spin coating method and operation are as follows: 0.045M Cu (C) was prepared in acetic acid solution, respectively₅H₇O₂）₂And 0.015M Bi (NO)₃）₃•5H₂And O. The two solutions were then mixed at a molar ratio of 1:2, and 20mL of acetylacetone was added to prepare a precursor. The precursor solution was uniformly spin coated on clean FTO glass at 1000 rpm for 20 seconds. Then drying the film on a hot plate at 150 ℃ for 10min, and annealing the film in a tube furnace at 600 ℃ for 1h to obtain the copper bismuthate film.

The sol-gel method and operation are as follows: 0.04mol of Bi (NO)₃）₃•5H₂O and 0.02mol Cu (NO)₃）₂•3H₂O was added to a beaker containing 60ml of acetone, 40ml of glycerol and 40ml of a mixed solvent of nitric acid, which functions to dissolve the solute, acetone and glycerol as a complexing agent and a high boiling point solvent stabilizer. Stirring and dissolving the mixture into sol at 50 ℃ by using a magnetic stirrer, and forming the sol into gel after 12 hours. Will be provided withDrying the gel in a tube furnace at 120 ℃ for 1h to form honeycomb porous gel. Then calcining the gel at 600 ℃ for 3h to obtain CuBi₂O₄A film.

The electrochemical deposition method and operation are as follows: first Bi (NO)₃）₃•5H₂O and Cu (NO)₃）₂•3H₂Dissolving O in 10% nitric acid to prepare Cu-Bi codeposition plating solution. Nitric acid requires first dissolving the bismuth nitrate precursor. Electrochemical deposition was carried out in a tripolar cell with Pt as the counter electrode and Ag/AgCl as the reference electrode. The films were deposited on FTO glass, cathodically electrodeposited in shop mode using a CHI660 potentiostat, rinsed in demineralised water and blown dry with nitrogen. Then annealing for 1h in a tube furnace at 600 ℃ to obtain the crystallized copper bismuthate film.

The results are shown in fig. 4, and it can be seen from the comparison in fig. 4d that the thin film is uniformly distributed on the substrate and the inter-grain connection is tight. In fig. 4d, the density and uniformity of the thin film obtained by the method of the present invention are improved compared with those of the other three methods (fig. 4a to 4 c).

In addition, the method provided by the invention is also suitable for preparing other ternary metal oxides by a magnetron sputtering method, and the structural composition and the optical band gap of the material can be changed by simply changing the power applied to the target material, so that the band gap of the material can be adjusted to a proper size.

Claims

1. The preparation method of the copper bismuthate film is characterized in that a magnetron sputtering method is utilized, and the vacuum degree is 4-8 x10^-4Introducing mixed gas of oxygen and argon into a Pa reaction cavity, respectively applying 5-40w of power to a copper target and 15w of power to a bismuth target through a radio frequency direct current power supply to form plasma, wherein the partial pressure of the argon is 0.75-0.85 Pa, and O is₂The partial pressure is 0.15-0.25 Pa, the deposition time is 10-20 min, and annealing is carried out in air for 15-25 min at 550-650 ℃ after deposition is finished.

2. The method of claim 1, wherein argon gas is used to form the copper bismuthate filmHas a partial pressure of 0.80Pa, O₂The partial pressure was 0.20 Pa.

3. The method for preparing a copper bismuthate film according to claim 1, wherein the annealing is performed at 600 ℃ for 20 minutes in air.

4. A preparation method for adjusting structural composition and optical band gap applied to ternary metal oxide is characterized in that a magnetron sputtering method is utilized, and the vacuum degree is 4-8 x10^-4And introducing mixed gas of oxygen and argon into the Pa reaction cavity, applying power to corresponding metal targets through a radio frequency direct current power supply respectively to form plasma and deposit, and annealing in the air at 400-800 ℃ after the deposition is finished.