Construction of metal oxide decorated ${\text{g-C}}_3{\text{N}}_4$ materials with enhanced photocatalytic performance under visible light irradiation

Herein we report the synthesis and photocatalytic evaluation of heterostructure ${\text{WO}}_3/{\text{g-C}}_3{\text{N}}_4$ (WMCN) and ${\text{CeO}}_2/{\text{g-C}}_3{\text{N}}_4$ (CMCN) materials for RhB degradation and photoelectrochemical studies. These materials were synthesized by varying the dosages of ${\text{WO}}_3$ and ${\text{CeO}}_2$ on ${\text{g-C}}_3{\text{N}}_4$ individually and were characterized with state-of-the-art techniques like XRD, BET surface area, FT-IR, UV–Vis DRS, TGA, SEM, TEM and XPS. A collection of combined structural and morphological studies manifested the formation of bare ${\text{g-C}}_3{\text{N}}_4$, ${\text{WO}}_3$, ${\text{CeO}}_2$, ${\text{WO}}_3/{\text{g-C}}_3{\text{N}}_4$ and ${\text{CeO}}_2/{\text{g-C}}_3{\text{N}}_4$ materials. From the degradation results, we found that the material with 10 wt% ${\text{WO}}_3$ and 15 wt% ${\text{CeO}}_2$ content on ${\text{g-C}}_3{\text{N}}_4$ showed the highest visible light activity. The first order rate constant for the photodegradation performance of WMCN10 and CMCN15 is found to be 5.5 and 2.5 times, respectively, greater than that of ${\text{g-C}}_3{\text{N}}_4$. Photoelectrochemical studies were also carried out on the above materials. Interestingly, the photocurrent density of WMCN10 photoanode achieved $1.45{\text{mA cm}}^{-2}$ at 1.23 V (vs.) RHE and this is much larger than all the prepared materials. This enhanced photoactivity of WMCN10 is mainly due to the cooperative synergy of ${\text{WO}}_3$ with ${\text{g-C}}_3{\text{N}}_4$, which enhanced the visible light absorption and suppresses the electron–hole recombination.

Graphical Abstract

Synopsis The WMCN materials exhibited superior photocatalytic performance than CMCN and bare ${\text{g-C}}_3{\text{N}}_4$ materials due to the existence of synergism between ${\text{WO}}_3$ and ${\text{g-C}}_3{\text{N}}_4$. .