Construction of novel an in-situ m-BiVO4/t-BiVO4 isotype heterojunction photocatalyst for improved visible light-dependent degradation of dye

In this article, we have studied the photocatalytic characteristics of isotype heterostructure Bismuth vanadate BiVO4 (m-BiVO4/t-BiVO4). The isotype Bismuth vanadate m-BiVO4/t-BiVO4 (MTBV) was formed by a facile hydrothermal method. It was observed that the crystalline phase of isotype MTBV could be controlled by modifying the pH values of the precursors in the hydrothermal method. The isotype MTBV heterojunction was investigated for its physicochemical features by different techniques including X-ray powder diffraction (XRPD), Field emission scanning electron microscopy (FESEM), Energy dispersive microscopy (EDS), Fourier transfer infrared (FTIR) spectroscopy, UV-visible diffuse reflectance spectroscopy (UV-Vis DRS), Photoluminance (PL), and Electrochemical impedance spectroscopy (EIS). Photocatalytic degradation of Congo red (CR) dye under visible light irradiation was used to determine the photocatalytic activity of a well-developed MTBV heterostructure. The isotype MTBV phase resulted in an increased response due to a faster electron-hole pair formation rate by reducing charge recombination processes, a reduction in optical energy band gap (2.52 eV), and good compatibility between Preston t-BiVO4 and m-BiVO4 photocatalyst. In 1 hr, the optimized isotype MTBV heterojunction showed a CR degradation of 98%. According to the results of the PL, EIS, and UV-Vis studies, isotype MTBV might be an excellent option for a blue/green visible light-dependent optical photocatalyst. A feasible photocatalytic mechanism was suggested and discussed in particular to relate the physiochemical properties and photocatalytic properties; furthermore, kinetics decomposition process study, scavenger effect, dye concentration, catalyst dose effect, reusability and stability were checked, respectively.