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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