Efficient charge transfer and separation of TiO2@NiCo-LDH core-shell nanowire arrays for enhanced photoelectrochemical water-splitting

Efficient charge transfer and separation play a significant role in determining the photoelectrochemical (PEC) water-splitting performance of photocatalysts. Here, hierarchical nanowire arrays (NWAs) containing the TiO2 nanowire core and nickel-cobalt layered double hydroxide (NiCo-LDH) shell were synthesized by combining a hydrothermal method with a facile electrochemical-deposition process. The hierarchical structure not only forms heterojunctions between the TiO2 core and NiCo-LDH shell but also provides active sites for water-splitting reaction, achieving the charge transfer efficiency up to 87% and the charge separation efficiency up to 42% at 1.23 V vs. reversible hydrogen electrode (RHE) under one sun illumination. The excellent PEC water-splitting performance of TiO2@NiCo-LDH core-shell NWAs is attributed to the enhanced charge transfer and separation, resulting from the decoration of the NiCo-LDH cocatalyst. This facile and cost-effective strategy for integrating the light-harvesting TiO2 semiconductor and NiCo-LDH cocatalyst into a hierarchical core-shell nanostructure can be potentially applied in energy conversion and environmental applications.