Copper decorated ZnO nanowires material: Growth, optical and photoelectrochemical properties

Abstract To reveal the photoelectricchemical (PEC) properties modulation and its mechanism is beneficial to the exploration of novel materials with excellent properties as well as the realization of their practical application. In this paper, uniform copper-decorated ZnO nanowires (Cu@ZnO NWs) were successfully prepared via the two-step chemical vapor deposition and then magnetron sputtering method. The structure, morphology, and composition of Cu@ZnO NWs at different sputtering time (ST) and sputtering power (SP) were characterized. The result of morphology characterization show of Cu on the surface ZnO NWs can be controlled by ST and SP adjustment. The optical and PEC properties of Cu@ZnO NWs were studied. All samples showed a strong linear absorption band due to the inherent absorption band of the ZnO nanowires in the near-ultraviolet range. The addition copper did not make any significant difference in its band gap. However, due to the surface plasmon resonance (SPR) absorption of the Cu nanostructures, the absorption spectrum peak at 558 nm is exhibited. The photoluminescence (PL) results proved two emission peaks for the Cu@ZnO NWs, which the sharp ultraviolet (UV) emission peak corresponding to the near band edge emission, and broad visible range originates from the electron-hole recombination at a deep level, caused by oxygen vacancy or zinc interstitial defects and the UV/visible emission peaks of Cu@ZnO NWs are weaker/stronger than that of pure ZnO nanowires. The PEC characteristics showed an increase/decrease in the current density of Cu@ZnO Nws with different ST/SP compared to that of unmodified ZnO nanowires. The experimental result shows that the PL and PEC properties of ZnO nanowires were regulated by Cu nanostructures with different morphologies. The ease of the synthesis route and the remarkable PL and PEC properties offer metal-semiconductor compound nanostructure materials as a promising electron source for high current density applications.