Enhanced solar-driven water splitting of 1D core-shell Si/TiO2/ZnO nanopillars

Abstract In this work, 1D core-shell Si/metal oxide nanopillar (NP) photoanodes were synthesized for enhanced solar-driven water splitting processes. The core-shell structures were fabricated by atomic layer deposition of different metal oxides (TiO2 and ZnO) onto Si NP, which were synthesized by metal-assisted chemical etching and nanosphere lithography. In order to characterize produced photoanodes various experimental techniques (SEM/TEM, XRD, Transmittance, Reflectance, Raman spectroscopy) were applied. Photoelectrochemical (PEC) water oxidation of produced photoanodes was studied. It was shown that composition of n-Si/TiO2/ZnO NP exhibited enhanced photocurrents due to barrier effects. The enhanced PEC properties of core-shell Si/TiO2/ZnO NP are caused by efficient charge separation of photogenerated electron-hole pairs in the TiO2/ZnO shell and effective holes transfer to the shell-electrolyte interface. The superior photoelectrochemical performance of a photoanode based on core-shell Si/TiO2/ZnO NP has been confirmed through electrochemical impedance spectroscopy and voltamperometric measurements under electrode irradiation. 1D core-shell Si/TiO2/ZnO NP offer a new approach for preparing stable and highly efficient photoanodes for PEC water-splitting process.