Enhanced photoelectrochemical performance of hydrogenated ZnO hierarchical nanorod arrays

•The preparation of hydrogenated ZnO hierarchical nanorod arrays is reported.•Oxygen vacancies are formed in hydrogenated ZnO.•Hydrogenated ZnO hierarchical nanorod arrays have an improved donor density and IPCE.

Hydrogenated ZnO (H-ZnO) hierarchical nanorod arrays (HNRAs) with enhanced photoelectrochemical performance have been reported for the first time. The H-ZnO samples were obtained by annealing the ZnO nanorod arrays (NRAs) and HNRAs in hydrogen atmosphere at 350 °C for 60 min. The electrochemical impedance measurements indicate the donor density of H-ZnO HNRAs achieved 5.1 × 1018 cm−3, which is higher than those of other ZnO samples. These H-ZnO HNRAs yields an improved photocurrent density of 1.72 mA cm−2 at 1.23 V vs. RHE, and the incident-photon-to-current-conversion efficiency (IPCE) values uniformly higher than 90% in the wavelength range from 300 to 370 nm, which are substantially higher than the pristine ZnO NRAs, ZnO HNRAs and H-ZnO NRAs. The ability to improve the photoelectrochemical properties of ZnO electrode materials may open up new opportunities for high-performance photovoltaic cells.

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