CN113638003A

CN113638003A - Nitride-based device for artificial photosynthesis and preparation method thereof

Info

Publication number: CN113638003A
Application number: CN202110896321.4A
Authority: CN
Inventors: 陈贵锋; 刘靳恬; 张辉; 解新建
Original assignee: Hebei University of Technology
Current assignee: Hebei University of Technology
Priority date: 2021-08-05
Filing date: 2021-08-05
Publication date: 2021-11-12

Abstract

The invention discloses a nitride-based device for artificial photosynthesis and a preparation method thereof. The device is a sapphire substrate from bottom to top, n⁺-a GaN layer, an AlGaN layer, a Cu-based promoter protective layer. The preparation process comprises the following steps: firstly growing an n-type GaN layer on a sapphire substrate, then growing an AlGaN layer on the n-type GaN layer by using a molecular beam epitaxy technology, etching part of the AlGaN layer by using an etching method, and preparing an ohmic contact at the etched position by using an evaporation methodAnd covering ohmic contact by using a mask, spin-coating a Cu-based promoter serving as a protective layer by using a spin-coating method, annealing for 30min at 300 ℃ in a vacuum tube furnace, naturally cooling to room temperature, and taking out to obtain the nitride device with the protective layer. The nitride device has higher absorption coefficient and good corrosion resistance, can be used as a photoanode material in artificial photosynthesis, and has important significance for reducing the concentration of carbon dioxide in air and developing energy sources.

Description

Nitride-based device for artificial photosynthesis and preparation method thereof

Technical Field

The invention relates to a nitride-based device having a Cu-based promoter protective layer and applied in the field of artificial photosynthesis.

Technical Field

With the development of economic society, the demand of people for energy is continuously increased, and the use of non-renewable energy sources such as coal, petroleum and the like is accompanied by a large amount of carbon dioxide (CO)₂) The emission of (2) also brings a series of environmental problems, such as greenhouse effect, global warming, glacier melting and the like.

It is known that green plants can assimilate carbon dioxide and water (H) by using solar energy₂O) produces organic matter and releases oxygen, with the production of carbohydrates, releasing energy. Carbon dioxide in the atmosphere can be reduced to products of industrial value by simulating photosynthesis in plants. In recent years, artificial photosynthesis has reduced CO₂Has become a research hotspot in the energy field, and various reduction methods such as photoelectrochemical reduction, electroreduction, chemical reduction, biological reduction and the like emerge. The reducing material is divided into an organic material and an inorganic material, wherein the inorganic material is environment-friendly and can realize the CO reduction in the electrolyte solution₂Reducing into organic matter and releasing oxygen.

In 2011 Satoshi Yotsuhashi demonstrated direct carbon dioxide conversion from CO using a Cu cathode and a gallium nitride electrode₂And H₂The faradaic efficiency of O to formic acid (HCOOH) was 3%. This result demonstrates direct CO in a system containing only inorganic materials₂The possibility of transformation.

In 2013, Satoshi Yotsuhashi uses metal organic vapor phase epitaxy method on sapphire with low-temperature gallium nitride buffer layerThe GaN electron transmission layer and the AlGaN light absorption layer are sequentially grown on the stone substrate, and a nickel oxide cocatalyst is adopted for enhancing the reaction and preventing the degradation, the size of nickel oxide particles is verified by a scanning electron microscope, the diameter of the nickel oxide particles is about 30 mu M, the height of the nickel oxide particles is 0.2 mu M, and a cathode is immersed into 0.5M KHCO on the cathode side₃The electrolyte, photoelectrode immersed in the anode side 1M NaOH electrolyte, had an energy conversion efficiency of 0.15%.

In 2019, Baowen Zhou directly forms a unique GaN-Sn nano structure on planar silicon by combining molecular beam epitaxy and electrodeposition, Sn is attached to the side edge of a GaN nano column in a nano particle form as a cocatalyst, and CO is well synergistically activated by covalent gallium-carbon bonds and ionic tin-oxygen bonds on an interface₂. Provides a promising approach for realizing low-cost, high-efficiency and strong artificial photosynthesis.

The materials have strong light absorption, but work in alkaline solution, the surface sample is easy to fall off, and the corrosion resistance is still required to be enhanced.

Disclosure of Invention

Aiming at the defects of the prior art, the invention provides a gallium nitride device for artificial photosynthesis and a preparation method thereof, the gallium nitride device can solve the problem that a photoanode material is corroded when working in an alkaline electrolyte solution, a protective layer of the gallium nitride device plays a role in protecting an AlGaN light absorption layer, and meanwhile, a Cu-based hole transport layer material is good in chemical stability, high in light transmittance and has certain hole transport capacity.

The nitride-based device for artificial photosynthesis of the invention is a sapphire substrate from bottom to top, n⁺-a GaN layer, an AlGaN layer, a Cu-based promoter protective layer, the Cu-based promoter being dispersed in a granular form on the AlGaN layer, the Cu-based promoter protective layer being: CuI, CuO, Cu₂One or more of O or CuS.

The nitride-based device for artificial photosynthesis of the present invention is prepared by the following steps: firstly growing an n-type GaN layer on a sapphire substrate, growing an AlGaN layer by using a molecular beam epitaxy technology, etching part of the AlGaN layer by using an etching method, preparing ohmic contact at the etched position by using an evaporation method, covering the ohmic contact by using a mask, taking a spin coating solution of a Cu-based cocatalyst as an organic solution, dispersing the Cu-based cocatalyst in solvents such as butyl acetate, propylene glycol methyl ether acetate and the like, ultrasonically oscillating for 30min by using an ultrasonic machine to obtain a granular dispersed metal organic decomposition solution (dispersion liquid), taking the metal organic decomposition solution obtained by spin coating on the AlGaN layer by using the spin coating method as a protective layer, and annealing for 30min at 300 ℃ to obtain the nitride device with the protective layer.

The nitride-based device for artificial photosynthesis has high light absorption coefficient, high electron-hole separation capacity and high corrosion resistance. Can be used in artificial photosynthesis to realize the reaction of CO₂Conversion to CH₄Hydrocarbons such as HCOOH.

Drawings

FIG. 1 is a schematic diagram of the structure of a nitride-based device of the present invention;

FIG. 2 shows the reduction of CO with a protective layer without Cu-based promoter as a photo-anode₂A comparison graph of the generated product and concentration;

fig. 3 is an SEM image of the device before (left) and after (right) the device was used as a photoanode.

Detailed description of the preferred embodiments

The invention is further described with reference to the following figures and specific embodiments.

Referring to fig. 1, the nitride-based device for artificial photosynthesis of the present invention is a sapphire substrate, n, from bottom to top⁺GaN layer, AlGaN layer, and Cu-based promoter protective layer (CuI, CuO, Cu may be used)₂O, CuS) and a Cu-based promoter is dispersed in a granular form on the AlGaN layer.

The preparation method comprises the following steps:

firstly growing an n-type GaN layer on a sapphire substrate, then growing an AlGaN layer by utilizing a molecular beam epitaxy technology, etching part of the AlGaN layer by an etching method, preparing ohmic contact at the etched position by an evaporation method, covering the ohmic contact by utilizing a mask, spin-coating a Cu-based cocatalyst as a protective layer on the AlGaN layer by a spin-coating method, then annealing for 30min at 300 ℃ in a vacuum tube furnace, naturally cooling to room temperature, and then taking out to obtain the nitride device with the protective layer.

The device is used as photoanode material In artificial photosynthesis experiment, In, Cu or Au is used as cathode, 1M NaOH is selected as anode electrolyte, and 1M KHCO is selected as cathode electrolyte₃The experiment is carried out under the irradiation of a 300W mercury lamp, the AlGaN light absorption layer generates electron-hole pairs under the irradiation of light, the holes reach the surface of the photoanode through the protective layer to participate in the water oxidation reaction, and the electrons are transmitted to the cathode through an external circuit to participate in the CO oxidation reaction₂Can realize the reduction of CO₂Conversion to CH₄Hydrocarbons such as HCOOH. The nitride-based device for artificial photosynthesis has high light absorption coefficient, good electron-hole separation capability and good corrosion resistance, and can obtain better photosynthesis effect, as shown in fig. 2, after reaction for 30min, by analyzing an SEM test chart (shown in fig. 3), the surface change is found to be small, the corrosion problem is effectively improved, and the nitride-based device for artificial photosynthesis has important significance in reducing carbon dioxide emission and responding to national carbon neutralization calls.

Claims

1. A nitride-based device for artificial photosynthesis is characterized in that the device is a sapphire substrate from bottom to top, and n is⁺The aluminum-based catalyst comprises a GaN layer, an AlGaN layer and a Cu-based promoter protective layer, wherein the Cu-based promoter protective layer is formed by dispersing Cu-based promoters on the AlGaN layer in a granular manner.

2. The nitride-based device of claim 1, wherein the Cu-based promoter is: CuI, CuO, Cu₂One or more of O or CuS.

3. The nitride-based device of claim 1, characterized in that it is prepared as follows: firstly growing an n-type GaN layer on a sapphire substrate, then growing an AlGaN layer by utilizing a molecular beam epitaxy technology, and etching part of the AlGaN layer to expose n below the AlGaN layer by an etching method⁺A GaN layer, ohmic contacts being produced at the etched-out locations by means of an evaporation method, the ohmic contacts being brought into contact with a maskCovering, spin-coating Cu-based promoter as a protective layer on the AlGaN layer by a spin coating method, and then annealing to obtain the nitride-based device for artificial photosynthesis.

4. The nitride-based device according to claim 3, wherein the spin-coating solution is a dispersion obtained by dispersing the Cu-based promoter in an organic solvent and shaking with ultrasound during spin-coating.

5. The nitride-based device of claim 3, wherein the annealing process is: annealing at 300 deg.C for 30 min.