Synthesis, structural characteristics, and photocatalytic performance of Zn3-xBix(VO4)2 heterostructures

In this research, Zn3-xBix(VO4)2 heterojunction for x = 0.00, 0.10, 0.20, 0.30, 0.60, and 0.80 has been fabricated using the hydrothermal synthesis route, as mixed metal vanadate (MVO) materials are considered an interesting class of semiconductors for photocatalysis due to their tunable properties of the bandgap for the light absorption in the visible range. The prepared heterojunction was analyzed by different characterization techniques: XRD, SEM, EDS, FTIR, XPS, UV–Vis, BET, EPR, and PL for physicochemical attributes. The effect of Bi+3 substitution on structure, photocatalysis, and electrochemistry was observed, and these results indicate that with an increase in Bi+3 concentration, the lattice constant increased while the lattice strain decreased. The Bi+3 substitution revealed improvements in the host Zn3(VO4)2 owing to the lowering of Urbach energy and an improvement in the crystallinity. The Bi+3 ion substitution delays the recombination rate and increases the lifetime of the photo-assisted charge carriers, which results in enhanced photocatalytic activity. The mixture with x = 0.30 exhibits superior photocatalytic response and charge separation efficiency. The scavenger study reveals that superoxide radicals (•O2¯) are the major species for the fast deprivation of Congo Red (CR) dye. The photoluminance study also revealed that the electron-hole recombination is much slower and more controlled in Zn2.70Bi30(VO4)2 as compared to other samples, which indicates defects within the Zn2.70Bi0.30(VO4)2 catalyst structure and allows more sites for reaction owing to mesoporous and nanoporous structures.