Preparation And Photoelectric Property Of Cu₂O With Copper Anode Oxidation Method

Cuprous oxide is a p-type semiconductor with a direct band gap of 2.0 eV and can be exitated by visible light. It has potential applications in solar energy conversion, electrode materials, sensors, and catalysis. So, cuprous oxide has become one of the hottest semiconductor nanomaterials.In this article, using NaCl as the anodic electrolyte and NaOH as cathodal electrolyte, Cu2O films by the method of copper anode oxidation have been prepared. They were characterized with the techniques of scanning electron microscopy, X-ray diffraction (XRD) pattern and X-ray photoelectron spectroscopy. Additionally, UV-Vis diffusion reflection spectroscopy (UV-Vis) and open ciruit were employed to record the photoelectrochemical properties of the nanostructures. Besides, we explored the effect of surfactants on the morphology of Cu2O thin film, and the sterilization property of the samples was also investigated.The results show that the sample we prepared through the method of copper anode oxidation is p-type Cu2O with the band gap of 1.97 eV. Both surface current density and surfactant have great impact on the morphology of Cu2O. When we use CTAB as the surfactant, with the increase of current density, the morphology of Cu2O can be nanonet, nanosheet and nanorod arrays respectively, among which nanorod cuprous oxide has the best activity in sterilization. When the surface current density was fixed to 10 A/m2, we can get needle-like, nanobelt, branch-like and nanowire Cu2O films when the anodic electrolyte contains a certain amount of CTAB, PVP, PEG respectively. And the nanowire Cu2O film has the best photoelectrochemical property.Additionally, the prepared Cu/Cu2O films were used as electrodes for catalytic reduction of CO2 in photochemical, electrochemical and photoelectrochemical system respectively. For comparison, n-type Cu2O through simple boiling process was also prepared. The results show that CH4 and C2H4 are the major hydrocarbon products in the above catalytic reduction systems and Cu2O thin film on Cu substrate has a higher selectivity for C2H4 production than blank copper electrode. The best yield for CO2 reduction is obtained in the photoelectrochemical system. The effect of electric field and visible light irradiation on the CO2 reduction was studied in detail. The stability of the Cu/Cu2O electrodes has been studied as well.