Sunlight driven photocatalytic degradation of organic pollutants by solvothermally synthesized rGO-BiVO4 nanohybrids

Abstract

This study reports photocatalytic degradation of organic dyes by rGO-BiVO4 nanohybrids. rGO- BiVO4 nanohybrids were solvothermally prepared with different rGO loading (1.5, 3 and 6 %) and their structural, optical and photocatalytic properties were investigated. Effect of rGO loading on photocatalytic dye degradation was studied and the factors responsible were analyzed. Structural analysis was done using XRD and Raman analyses which clearly showed monoclinic phase of the BiVO4. FESEM images showed sub-micron spheres of BiVO4 along with sheet-like structures corresponding to rGO. A slight change in the band gap was observed from 2.2 eV for BiVO4 to around 2 eV for the rGO-BiVO4 nanohybrids. Band to band transitions as well as the transitions from the defect bands were observed from the PL spectra. Photocatalytic degradation studies of organic pollutant MB under natural sunlight showed 3 % rGO-BiVO4 to be the best photocatalyst which degraded 88.4 % of MB in 80 min with rate constant of 0.0244 min−1. It was observed that for obtaining a maximum catalytic efficiency an optimum loading of rGO proved to be best. In either case of higher or lower loading of rGO showed a lower degradation performance. Amongst the samples synthesized 3 % rGO loading was found to be the optimum rGO loading to have the lowest band gap (2 eV) as well as the reduced recombination that has resulted in highest photocatalytic efficiency under solar irradiation.