Hydrothermal synthesis of (m-t)BiVO4/g-C3N4 heterojunction for enhancement in photocatalytic degradation of imidacloprid

Bismuth vanadate (BiVO4) has gained significant attention as a photocatalyst due to lower band gap energy and its effectiveness in the degradation of both organic and inorganic pollutants. In this study, BiVO4 and nanocomposites of BiVO4 with g-C3N4 were synthesized by varying g-C3N4 compositions using hydrothermal technique. Thereafter the catalysts were assessed for the degradation and mineralization of imidacloprid (IMD). The catalysts were characterized using SEM, BET, XRD, UV-Vis DRS, photoluminescence spectroscopy, and XPS techniques to analyze the various properties for its effectiveness. XRD studies reveals the monoclinic as well as tetragonal phase in synthesized BiVO4 and its composite. In a UV-C light with an intensity of 15 W/m2 and at neutral pH, the degradation rate was significantly higher (94.2%) for BiVO4/g-C3N4 (90:10), denoted as BVCN10, compared to the bare BiVO4 nano-catalyst (83.2%) within a short period of 30 min. BVCN10 catalyst reported higher surface area, improved visible light absorption capacity, and lower electron-hole recombination, presence of monoclinic and tetragonal phases which might have enhanced its photocatalytic activity thereby accelerating degradation efficiency. Kinetic studies show that the degradation of IMD follows the first-order rate law with a rate constant (k) 0.11 min−1. Furthermore, BVCN10 can be used five times without losing catalytic activity, making it a reliable nanocatalyst with economic and environmental benefits.