A novel photoanode based on Thorium oxide (ThO2) incorporated with graphitic Carbon nitride (g-C3N4) for Photoelectrochemical water splitting

[Display omitted] •The g-C3N4/ThO2 photoanode was successfully undergo polymerization process then fabricated by the spin-coating method.•The enhanced separation of photo-generated electron–hole pairs reduced the carrier recombination that was obviously probed via PL.•Doping with ThO2 increased the intensity of triazine and C-N bond in the g-C3N4 network, as observed by FT-IR analysis.•The 1 layer of g-C3N4/ThO2 photoanode by spin-coating method yielded the optimum photocurrent density reaching ~9.71 μcm−2 at 1.23 V vs. Ag/AgCl under simulated light (100 mW/cm2). In this study, a new insight into the doping engineering with nuclear fuel (ThO2) was performed and applied in photoelectrochemical (PEC) water splitting. The successfully synthesized g-C3N4/ThO2 (~5.8%) via thermal treatment and g-C3N4 polymerization (precursor: Urea, 30 min; 520 ˚C) manifested a remarkable and superior photocatalytic activity. The photocurrent density achieved for g-C3N4/ThO2 was 9.71 μcm−2 at 1.23 V vs. Ag/AgCl under simulated light (100 mW/cm2) that is more than twice compared with the un-doped g-C3N4 (~4.23 μA cm−2). The introduction of Thorium Nitrate during g-C3N4 polymerization altered the chemical bonding, structure, and morphology, with the improved PEC stability of the photoanode. Besides, doping with ThO2 increased the intensity of triazine and C-N bond in the g-C3N4 network, as observed by FT-IR analysis. The unique “hollow cylindrical” architecture also increased the surface area, light absorption, as well as the catalytic sites. The enhanced separation of photo-generated electron–hole pairs reduced the carrier recombination that was obviously probed via Photoluminescence spectra. Therefore, due to the photostability and the good performance, the g-C3N4/ThO2 composite can be envisioned as a potential candidate in the field of photocatalysis and prospectively be applied in PEC solar water splitting.