A photodegradation study of the deposition fabricated CdS–BiVO4 binary catalyst: a brief comparison with other fabrication procedures†

In the present study, Eriochrome black T (EBT) degradation in an aqueous environment was carried out by CdS–BiVO₄ integrated catalysts prepared using several integrated methods. The catalyst prepared via the deposition method showed the highest activity. The catalysts were identified using XRD, FTIR, SEM, UV-Vis DRS, and cyclic voltammetry (CV). The crystallite size of the binary catalyst was obtained at about 25.3 nm and 45 nm by the Scherrer and Williamson–Hall methods. Since the response surface methodology (RSM) is one of the efficient modeling methods, it was used to investigate the simultaneous effects of the effective parameters (catalyst amount, pollutant concentration, pH, and irradiation time) on the photocatalytic degradation. R² showed good agreement between the experimental results and the data predicted by the software. Also, the predicted square model was very satisfactory with high correlation coefficients R² (0.9839) and adj R² (0.9688). The optimal-run conditions were C_EBT: 15 ppm, catalyst dose: 0.9 g L⁻¹, pH: 7.3, and illumination time: 20 min. The effect of some inhibitory agents was evaluated, and it was found that the role of superoxide radicals and the holes in the degradation of EBT is more critical than that of hydroxyl radicals and photoinduced electrons, based on the direct Z-scheme mechanism proposed for charge carriers’ transfer. The process obeyed a pseudo-first-order kinetic with the apparent rate constant of 0.0614 min⁻¹.