Heterojunction catalysts g-C₃N₄/-3ZnO-c-Zn₂Ti₃O₈ with highly enhanced visible-light-driven photocatalytic activity

In this study, pristine ZnO, TiO₂, hexagonal-ZnTiO₃, and cubic-Zn₂Ti₃O₈ nanoparticles were synthesized by varying the molar ratio of ZnO/TiO₂ by sol–gel method assisted with calcinations at 500 °C for 2 h in air. Compared with the pristine phase of zincite (ZnO) and anatase/rutile (TiO₂), hybrid nanostructures with 3ZnO:1TiO₂ (3ZT) that retain zincite and c-Zn₂Ti₃O₈ demonstrated a higher photocatalytic activity (~82% degradation within 45 min). 3ZT photocatalyst that has been loaded with 10 wt% g-C₃N₄ has further enhanced visible-light photocatalytic activity performance up to ~99% degradation within 45 min under sunlight illumination. The bandgap energy of 2.5 eV, the formation of a heterojunction of 10g-C₃N₄/-3ZnO-c-Zn₂Ti₃O₈, crystalline nature of the phases, and high quantity of surface OH⁻ resulted in higher adsorption of organic molecules, causing a substantial improvement in degradation of methylene blue (MB) from ~1.8 to 2.2% per min, which in turn was ~70% better than other reported work. [Figure not available: see fulltext.].