Synthesis of a novel SnO2/graphene-like carbon/TiO2 electrodes for the degradation of recalcitrant emergent pharmaceutical pollutants in a photo-electrocatalytic system

Abstract

Photo-electro catalysis (PEC) has emerged as an efficient, sustainable, and green technology for the treatment of recalcitrant compounds, where anode plays a critical role. Novel preparation methods for anodes as catalysts should be considered in order to achieve larger active sites and diverse oxidants production, which can directly enhance the degradation performance. Therefore, in this work, a new cheap and green electrode material modification or synthesis method was studied. A graphene-like carbon mesoporous layer and SnO2 layer over TiO2 was produced and it resulted in higher porosity and stability of the electrode. This led to dominating advantage on photo/electrocatalytic activity and degradation performances. Synthesized electrodes attribute better charge separation and it was analyzed by electrochemical characterization. Hydroxyl radicals and superoxide (O2−) radicals were dominant oxidants in the degradation process based on the catalytic and degradation mechanism. However, the synergistic effect of photo and electro-catalytic degradation performances shrank under unoptimized PEC operational parameters. Therefore, the effect of various PEC parameters for the degradation of emerging pollutants was optimized. It was found that 90% degradation of emergent pollutants was achieved at optimized PEC operational parameters within 60 min of reaction time. Intermediates via PEC degradation of emerging pollutants were identified and a possible removal pathway was thus proposed. The three-dimensional SnO2-G-TiO2 electrodes hold great potential for PEC treatment of wastewater treatment.