Bi2WO6/Ag3PO4 as a new n–n heterojunction photocatalyst: Synthesis, charge transfer mechanism, and enhanced blue-light-driven photocatalysis for simultaneous degradation of dye pollutants

A simple one-pot hydrothermal method was successfully used to synthesize n–n heterojunction Bi2WO6/Ag3PO4 composites and subsequently this new material was characterized by FT-IR, EDS, powder XRD, FESEM, UV-Vis-DRS and PL spectroscopy. The n-Bi2WO6/n-Ag3PO4 were efficiently used as blue-light-driven photocatalyst for the simultaneous degradation of methyl green (MG) and auramine O (AO) dyes. Several experiments were designed by central composite design (CCD) where parameters including irradiation time, pH, n-Bi2WO6/n-Ag3PO4 mass as well as MG and AO concentrations involved in process were optimized. The significance of individual parameters and their possible interactions was investigated using the analysis of variance (ANOVA). Kinetics as an essential step in the photocatalytic process was investigated, which showed that pseudo first order kinetics based on Langmuir-Hinshelwood (L-H) model well describes the experimental data. This kinetics model showed more significant photodegradation of MG and AO dyes compared to their surface adsorptions, which is great advantage of this work besides the application of blue light in the process. The n-Bi2WO6/n-Ag3PO4 was found to be very stable visible-light-driven photocatalyst where its reusability was successfully examined for 6 times. The reasonably high photodegradation efficiencies obtained by a short-time process as well as the neutral working pH, high stability and reusability of the cost-effectively prepared n-Bi2WO6/n-Ag3PO4 make them promising for such photocatalytic applications [1-3].