Herein, for the first time, an efficient photoanode engineered with the cascade structure of FTO|c-TiO2|few graphene layers|TiO2/GQDs|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|c-TiO2|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.

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