Synthesis of ZnO/Cu₂S core/shell nanorods and their enhanced photoelectric performance

In this work, two kinds of ZnO/Cu₂S core/shell nanorods (NRs) have been successfully synthesized from ZnO NRs for photoelectrochemical (PEC) water splitting by a versatile hydrothermal chemical conversion method (H-ZnO/Cu₂S core/shell NRs) and successive ionic layer adsorption and reaction method (S-ZnO/Cu₂S core/shell NRs), respectively. The photoelectrode is composed of a core/shell structure where the core portion is ZnO NRs and the shell portion is Cu₂S nanoparticles sequentially located on the surface. The ZnO NRs array provides a fast electron transport pathway due to its high electron mobility properties. The optical property of both two kinds of core/shell NRs was characterized, and enhanced absorption spectrum was discovered. Our PEC system produced very high photocurrent density and photoconversion efficiency under 1.5 AM irradiation for hydrogen generation. On the basis of a versatile chemical conversion process based on the ion-by-ion growth mechanism, H-ZnO/Cu₂S core/shell NRs exhibit a much higher photocatalytic activity than S-ZnO/Cu₂S core/shell NRs. The photocurrent density and photoconversion efficiency of H-ZnO/Cu₂S core/shell NRs are up to 20.12 mA cm⁻² at 0.85 V versus SCE and 12.81 % at 0.40 V versus SCE, respectively.