A Hierarchical 3D TiO<sub>2</sub>/Ni Nanostructure as an Efficient Hole‐Extraction and Protection Layer for GaAs Photoanodes
Mahdi Alqahtani, Andreas Kafizas, Sanjayan Sathasivam, Mohamed Ebaid, Fan Cui, Ahmed Y. Alyamani, Hyeon‐Ho Jeong, Tung‐Chun Lee, Peer Fischer, Ivan P. Parkin, Michaël Grätzel, Jiang Wu
Abstract
Abstract Photoelectrochemical (PEC) water splitting is a promising clean route to hydrogen fuel. The best‐performing materials (III/V semiconductors) require surface passivation, as they are liable to corrosion, and a surface co‐catalyst to facilitate water splitting. At present, optimal design combining photoelectrodes with oxygen evolution catalysts remains a significant materials challenge. Here, we demonstrate that nickel‐coated amorphous three‐dimensional (3D) TiO 2 core‐shell nanorods on a TiO 2 thin film function as an efficient hole‐extraction layer and serve as a protection layer for the GaAs photoanode. Transient‐absorption spectroscopy (TAS) demonstrated the role of nickel‐coated (3D) TiO 2 core‐shell nanorods in prolonging photogenerated charge lifetimes in GaAs, resulting in a higher catalytic activity. This strategy may open the potential of utilizing this low‐cost (3D) nanostructured catalyst for decorating narrow‐band‐gap semiconductor photoanodes for PEC water splitting devices.