A Three-Dimensional Branched TiO₂ Photoanode with an Ultrathin Al₂O₃ Passivation Layer and a NiOOH Cocatalyst toward Photoelectrochemical Water Oxidation

Photoelectrochemical (PEC) water splitting provides an alternative strategy for clean and renewable hydrogen production; however, the practical application is severely limited by the low solar conversion. Herein, a novel and simple strategy has been developed to construct a 3D branched TiO2 photoanode with an ultrathin Al2O3 passivation layer and NiOOH cocatalyst. The structure and properties of the as-obtained photoanodes are explored by X-ray diffraction, Mott–Schottky, electrochemical impedance spectroscopy, and open circuit voltage measurements. The as-obtained B-TiO2/Al2O3/NiOOH ternary heterojunction with a high-quality contact interface exhibits improved light absorption ability, an enhanced photocurrent density of 1.42 mA/cm2 at 1.23 VRHE, high conversion efficiency (0.44% at 0.80 VRHE), and excellent stability compared to pristine TiO2 and alone-Al2O3 or NiOOH decorated TiO2 photoanodes. Therefore, this work could offer a new approach to designing and fabricating high-quality contact interfaces between photoelectrodes and various cocatalysts.