Construction of CdS@ZnO core–shell nanorod arrays by atomic layer deposition for efficient photoelectrochemical H2 evolution

Photoelectrochemical (PEC) water splitting provides a promising strategy for the production of clean hydrogen fuel. Herein, a new CdS@ZnO core–shell nanorod arrays (NRAs) is successfully constructed by atomic layer deposition (ALD) for H2 evolution from PEC water splitting. The CdS@ZnO200 obtained after 200 ALD cycles presents a significantly enhanced PEC H2 evolution rate of 21.64 μmol·h−1·cm−2, which is about 9.4 times of pristine CdS NRAs (2.31 μmol·h−1·cm−2). The reasons for the improved PEC H2 evolution performance can be ascribed to several aspects: firstly, the Z-scheme charge transfer mechanism formed between CdS core and ZnO shell promotes the effective spatial separation of photo-induced electrons and holes; secondly, the close contact between the two semiconductors resulted from ALD process helps to reduce the transfer resistance of charge carriers. In addition, the CdS core is tightly wrapped by ZnO shell, which helps to prevent the photo-corrosion of CdS core. This work provides a new type of photoanode material suitable for PEC H2 evolution from water splitting, and provides an efficient anti-corrosion method for the use of photocorrosive semiconductor materials.