Preparation of the TiO₂/Graphic Carbon Nitride Core–Shell Array as a Photoanode for Efficient Photoelectrochemical Water Splitting

The photoelectrochemical (PEC) oxygen evolution reaction over a photoanode is a promising process for renewable energy. The fascinating properties of graphic carbon nitride (g-CN) in water splitting make the photoelectrode engineering of it for PEC use quite meaningful. In this work, we report the fabrication of the core–shell-structured TiO 2 /g-CN composite film by hydrothermal growth for TiO 2 nanorod arrays and solvothermal growth for the g-CN layer. Herein, TiO 2 is used as an effective electron-transfer layer, and g-CN is used as a visible light absorption layer. Different reaction conditions were investigated in order to obtain the uniform TiO 2 /g-CN nanorod core–shell structure. Outstanding photoelectrochemical performances of the optimized composites were obtained compared to that of pristine TiO 2 or g-CN because the high-quality heterojunction between g-CN and TiO 2 turned out to effectively reduce the recombination of charge carriers and improve the photoelectric conversion ability. Thus, the photocurrent density under visible light of TiO 2 /g-CN reached 80.9 μA cm –2, which is 21 times that of g-CN under 0.6 V (vs SCE). Finally, a systematic photoelectrocatalytic mechanism of charge carrier migration and the recombination path in the TiO 2 /g-CN nanorod core–shell heterojunction was proposed, which can be considered to be a probable explanation of efficient PEC performance.