Photoelectrochemical Water Splitting: A Visible-Light-Driven CoTiO 3 @g-C 3 N 4 -Based Photoanode Interface Follows the Type II Heterojunction Scheme.

Harnessing solar energy can be efficiently used to generate hydrogen by photochemical water splitting, which is a sustainable and environmentally benign energy source. Here, a unique visible-light-driven CoTiO 3 @g-C 3 N 4 (CTOCN)-based photoanode interface has been optimized and developed with modification to follow the type II heterojunction for the enhancement of photoelectrochemical water splitting. Initially, a graphitic carbon nitride-loaded CoTiO 3 (with 10 wt % g-C 3 N 4 ) composite was obtained using a one-pot solvothermal method. Accordingly, the type II heterojunction interface between g-C 3 N 4 and CoTiO 3 has been successfully created and confirmed by the acquired phase, morphological, and optical examinations. Thereby, heterostructure generations with interfacial interaction were enabled to decrease photogenerated electron-hole pair recombination, leading to enhanced charge transfer for water oxidation kinetics. The minimal charge transfer resistance and hole relaxation lifetime ( p ) shown in Nyquist and Bode plots have further confirmed the rapid electron transport across the electrode/electrolyte interfaces, which is attributed to an enhanced absorption of holes for the water splitting process. Additionally, UV-vis spectroscopy, Mott-Schottky analysis, and UPS studies were used to determine the band edge locations of g-C 3 N 4 and CoTiO 3 . In comparison to previously developed nanohybrids and their equivalents, the CTOCN-d photoanode follows the type II charge transfer mechanism, resulting in a higher photocurrent density of 55.51 mA cm -2 .