Influence of C 3 N 4 Precursors on Photoelectrochemical Behavior of TiO 2 /C 3 N 4 Photoanode for Solar Water Oxidation

Photoelectrochemical water splitting is considered as a long-term solution for the ever-increasing energy demands. Various strategies have been employed to improve the traditional TiO 2 photoanode. In this study, TiO 2 nanorods were decorated by graphitic carbon nitride (C 3 N 4 ) derived from different precursors such as thiourea, melamine, and a mixture of thiourea and melamine. Photoelectrochemical activity of TiO 2 /C 3 N 4 photoanode can be modified by tuning the number of precursors used to synthesize C 3 N 4 . C 3 N 4 derived from the mixture of melamine and thiourea in TiO 2 /C 3 N 4 photoanode showed photocurrent density as high as 2.74 mA/cm 2 at 1.23 V vs. RHE. C 3 N 4 synthesized by thiourea showed particle-like morphology, while melamine and melamine with thiourea derived C 3 N 4 yielded two dimensional (2D) nanosheets. Nanosheet-like C 3 N 4 showed higher photoelectrochemical performance than that of particle-like nanostructures as specific surface area, and the redox ability of nanosheets are believed to be superior to particle-like nanostructures. TiO 2 /C 3 N 4 displayed excellent photostability up to 20 h under continuous illumination. Thiourea plays an important role in enhancing the photoelectrochemical performance of TiO 2 /C 3 N 4 . This study emphasizes the fact that the improved photoelectrochemical performance can be achieved by varying the precursors of C 3 N 4 in TiO 2 /C 3 N 4 heterojunction. This is the first report to show the influence of C 3 N 4 precursors on photoelectrochemical performance in TiO 2 /C 3 N 4 systems. This would pave the way to explore different precursors influence on C 3 N 4 with respect to the photoelectrochemical response of TiO 2 /C 3 N 4 heterojunction photoanode.