Cuprous Oxide And Zinc Oxide Composite Material For Photoelectrochemical Water Splitting

Cuprous oxide is of extremely important research value in the photoelectric chemical decomposition of water as metal-oxide semiconductor material with a proper band gap (2.17eV) for absorption of visible light. Since producing hydrogen capacity is far superior to producing oxygen capacity for the cuprous oxide, the research about it focuses mainly on hydrogen evolution reaction. Little study is drawn on oxygen evolution reaction. As a known metal-oxide semiconductor material in the photoelectrochemical decomposition of water, Zinc oxide, especially its nanowires, has excellent prospects for applications.As an effective means, heterojunction structure to enhance the photoelectrochemical water splitting capacity has become a consensus.This paper theoretically analyzes the energy band structure of cuprous oxide and zinc oxide, indicating the great advantages of the combination of the two oxides in the decomposition of water. We synthesized cuprous oxide particles with different morphologies by simple hydrothermal, including spherical, hexagonal, octahedron and rhombic dodecahedron, and give a brief analysis of its mechanism in the growth process;we also prepared the nanowires of zinc oxide with the average diameters less than100nm by the CVD method and combined them to form a heterojunction and use the SEM to observation their morphologies. Comparison of the photoelectronchemical performance of copper oxide, zinc oxide and their composites, the main results are as follows:1. The electrochemical water splitting I-V test results show that the dark current value of Cu2O-ZnO composite structure is higher than that of the pure zinc oxide or cuprous oxide at+1.4V voltage, which indicates that the composite structure in the electrochemical water splitting exceeds the pure cuprous oxide and zinc oxide performance.2. The photoelectrochemical water splitting I-V test results show that the photocurrent value of Cu2O-ZnO composite structure is higher than that of the pure zinc oxide or cuprous oxide at+1.4V voltage, indicating that the composite structure in the photoelectrochemical water splitting exceeds the pure cuprous oxide or zinc oxide performance.3. The photoelectrochemical water splitting I-t test results show that the cuprous oxide, zinc oxide and composite structure with a stable current value after25minutes at+1.0V voltage have a significant decrease compared to the initial current value, attributed to chemical instability of the zinc oxide and cuprous oxide; However, we also found that stable current value of Cu2O-ZnO composite structure is maximum, higher than that of the pure cuprous oxide or zinc oxide, which shows that the composite structure is more stable than the pure zinc oxide or cuprous oxide. We also give a briefly analysis of the stability by XRD and SEM.4. The photoelectrochemical water splitting I-V test of the composite structure with different thickness showed that:the light current is highest with thickness of5μm, and the photocurrent is reduced when the thickness deposited to10μm or2μm, indicating that cuprous oxide layer thickness in Cu2O-ZnO composite structure is an important factor.The composite structure in the dark current value, the value of the photocurrent and chemical stability is better than the pure cuprous oxide or zinc oxide performance in the photoelectrochemical splitting of water. This is our first time attempt to enhance Cu2O photoelectrochemical water splitting oxygen capacity by using the composite structure.