Studies On Fabrication, Modification And Photoelectrochemical Performance Of Cuprous Oxide Photoelectrode

Identify and establish a sustainable energy system is the key issue which must be addressed in today’s society. Hydrogen energy because of its abundant and cheap raw materials, easy to store and transport, environment friendly, is regarded as the most promising clean energy. Through photoelectrochemical water splitting using of free and unlimited solar energy is considered as one of the most promising hydrogen production method. As one of few natural p-type semiconductor metal, cuprous oxide(Cu2O) is thought of by many as the most promising candidate for e ffcient photocathode material due to the following reasons:(1) it has a band gap of-2.0 eV, which guarantees effcient visible light absorption;(2) its conduction band edge lies-0.7 eV(vs NHE), which allows Cu2 O to drive water reduction reaction as photocathode;(3) the natural abundance of copper on the earth’s crust makes the large-scale fabrication of a Cu2 O photoelectrode. However, the practical application of C u2 O in the PEC process is still limited by two main drawbacks:(1) the short intrinsic carrier diffusion length(usually 20-100 nm); and(2) its poor stability due to self-photocorrosion in electrolyte solution. In the present research, to increase the photoelectrochemical activity and stability of cuprous oxide, the methods such as the constructing the nanostructure of cuprous oxide, modification of a protective layer or co- catalyst on the surface have been adopted.The main contents of this paper include the following two aspects:(1.)Preparation of copper hydroxide nanowires by anodic oxidation method with 10 mA /cm2 current density. Then calcined at 550℃ under nitrogen atmosphere to obtained cuprous oxide nanowires. In order to improve the photoelectrochemical activity and the stability of cuprous oxide, we modified the photoelectrode with carbon layer and the nickel oxide layer successively by using glucose and nickel acetate as precursor. The photoelectric property of photoelectrode. The effects of different glucose concentration and nickel acetate concentration on photoelectric property of the photoelectrode were analyzed and compared. The results shows that when the concentration of glucose was 3 mg/mL, the photoelectrochemical activity and the stability of the photoelectrode with modified with carbon layer were significantly improved; when the concentration of nickel acetate was 0.2mg/mL, the photoelectrochemical activity and stability of the modified photoelectrode get further improved; the photoelectrode modified with carbon layer and nickel oxide together has a higher photocurrent than the photoelectrode modified with carbon layer or nickel layer alone, which produces a synergistic effect.(2). We have deposited the metal nickel on the surface of cuprous oxide photoelectrode as a co-catalyst by using electrolytic method in organic solvent NMF. The effect of different deposition current density on the photoelectric properties of the photoelectrode were test by photoelectrochemical. We found that at the current density of 10 mA /cm2 for 10 s, the photoelectric activity of the photoelectrode increased significantly, but the stability of photoelectrode still stay poor. Therefore, the photoelectrode modification with the metal nickel have oxidedation treatment at 160 ℃ for 30 min to oxidation, and formed copper oxide protection layer and nickel / nickel-oxide core-shell structure on the surface of photoelectrode. And the photoelectrochemical activity and stability of the photoelectrode have been further i mproved.