Fabrication of BiOI/graphene Hydrogel/FTO photoelectrode with 3D porous architecture for the enhanced photoelectrocatalytic performance

Abstract Three-dimensional (3D) porous networkstructural BiOI-graphene hydrogel-FTO (BiOI/GH/FTO) electrode with remarkably superior photoelectrocatalytic degradation activity and photoelectrocatalytic mineralization ability was successfully prepared by a two-step electrodeposition method. The BiOI nanosheets were electrodeposited into the architectures of 3D porous graphene hydrogel which was prepared by the electrochemical reduction of GO in aqueous dispersion. The morphology and amount of BiOI can be controlled by the electrochemical deposition. With the deposition time of BiOI for 60 s and the working voltage at 1.0 V, the photoelectrocatalytic activity of the 3D BiOI/GH/FTO achieved to the maximum. The removal rate of phenol can be up to about 83% in 5 h, which was 13.8 times higher than that of BiOI/FTO electrode. The degradation rate and mineralization rate of phenol in the solution absence of Na2SO4 electrolyte were 76.8% and 56.8%, respectively, which were 13.2 times and 33.4 times as high as that of the BiOI/FTO. The enhanced photoelectrocatalytic degradation activity of 3D BiOI/GH/FTO is due to the 3D porous architecture and a larger surface area of graphene hydrogel which is favorable for reactant diffusion, and the superior electrical conductivity which promotes the charges to transfer excited by BiOI. The BiOI/GH/FTO electrode has the excellent stability. The degradation rates of phenol nearly unchanged after 4 cyclic degradations in static system and a long-term degradation for 72 h in dynamical system. Trapping experiment shows that the hole might be the main active species in photoelectrocatalytic degradation. This research provides new insights in the development of a new photoelectrocatalytic material for the removal of organic compound.