Highly enhanced photocatalytic property dominantly owing to the synergic effects of much negative Ecb and S-scheme heterojunctions in composite g-C3N4/Mo-doped WO3

Abstract

In this work, an S-scheme heterojunction-structured composite, g-C3N4/Mo-doped WO3 (mass ratio 100:5, labeled 5M15WOCN) together with pure WO3, g-C3N4, and Mo-doped WO3 (labeled M15WO) was prepared. The as-prepared samples were characterized by XRD, UV–Vis DRS, SEM, TEM, ESR, EIS, PL and XPS. The photocatalytic properties were investigated by photodegrading methyl orange (MO). The following findings were obtained. The dopant Mo increased the amount of Ov-s and produced W5+, along with prolonging the lifetime of photogenerated carriers, improving the transfer ability of carriers. The S-scheme heterojunction g-C3N4/M15WO drastically improved the photocatalytic properties, dominantly due to the synergetic effect of the Ov-s, S-scheme mechanism and very negative CB potential. A new phenomenon is found in which W6+ can combine with the net electrons coming from the side with a higher Fermi level in the heterojunction and form W5+, suggesting a good method for stabilizing the high valence state for the material by combining one with a lower Fermi level. This work also implies that, compared to the S-scheme, a more negative CB is much more beneficial for MO photodegradation.