Photoelectrochemical water splitting by engineered multilayer TiO2/GQDs photoanode with cascade charge transfer structure

Herein, for the first time, an efficient photoanode engineered with the cascade structure of FTO vertical bar c-TiO2 vertical bar few graphene layers vertical bar TiO2/GQDs vertical bar Ni(OH)(2) assembly (Ni(OH)(2) photoanode) is designed. This photoanode exhibited much lower electron-hole recombination, fast charge transport, higher visible light harvesting, and excellent performance with respect to FTO vertical bar c-TiO2 vertical bar TiO2 assembly (TiO2 photoanode) in the photoelectrocatalytic oxygen evolution process. The photocurrent density of Ni(OH)(2) photoanode is 7 times (0.35 mA cm(-2) at 1.23 V vs. RHE) greater than that of TiO2 photoanode (0.045 mA cm(-2) at 1.23 V vs. RHE). The compact TiO2 (c-TiO2) layer in Ni(OH)(2) photoanode plays a role of an effective hole-blocking layer. Few-layer graphene layer could speed up the transport of the photogenerated electrons from the conduction band of the TiO2/GQDs to FTO. Ni(OH)(2) layer could transfer rapidly holes into electrolyte solution. (C) 2019 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.