Synergistic effects of ThO2 on g-C3N4/BiVO4 heterojunctions for enhanced photoelectrochemical (PEC) water splitting

In this study, we unveil a groundbreaking approach, incorporating dopants and engineering heterojunctions, to craft an exceptional g-C3N4/ThO2@BiVO4 photoanode through a two-step process of methanolic dispersion spincoating followed by electrodeposition (ED) method. The PEC cells utilizing the g-C3N4/ThO2@BiVO4 heterojunction photoanode outperform both the g-C3N4/BiVO4 and standalone BiVO4, with the g-C3N4/ThO2@BiVO4 achieving a notably enhanced photocurrent density of 0.45 mA cm-2 at 1.23 V vs. RHE. This signifies a substantial improvement over the photocurrent densities of 0.32 mA cm-2 and 0.21 mA cm-2 attained by the gC3N4/BiVO4 and BiVO4 photoanodes, respectively. Exhibiting a distinctive dual-nanostructure morphology, the deposited g-C3N4/ThO2@BiVO4 photoelectrode constructs a 'spongy' and 'needle-like' nanoflower architecture, ultimately converging into a densely packed agglomerate. The incorporation of Oxygen and about 5.8% Th4+- doping not only induces noteworthy photostability but also amplifies charge transfer efficiency while concurrently mitigating charge recombination within the g-C3N4/ThO2@BiVO4 photoanode, achieved through the creation of defects, as elucidated in XPS and Raman analyses. Our in-depth exploration highlights the exceptional performance and photostability of the g-C3N4/ThO2@BiVO4 photoanode, establishing it as an auspicious candidate for applications in photoelectrochemical (PEC) water splitting.