Synergistic catalysis of TiO/WO photoanode and Sb-SnO electrode with highly efficient ClO• generation for urine treatment.

Urine is the major source of nitrogen pollutants in domestic sewage and is a neglected source of H. Although ClO• is used to overcome the poor selectivity and slow kinetics of urea decomposition, the generation of ClO• suffers from the inefficient formation reaction of HO• and reactive chlorine species (RCS). In this study, a synergistic catalytic method based on TiO/WO photoanode and Sb-SnO electrode efficiently producing ClO• is proposed for urine treatment. The critical design is that TiO/WO photoanode and Sb-SnO electrode that generate HO• and RCS, respectively, are assembled in a confined space through face-to-face (TiO/WO//Sb-SnO), which effectively strengthens the direct reaction of HO• and RCS. Furthermore, a Si solar panel as rear photovoltaic cell (Si PVC) is placed behind TiO/WO//Sb-SnO to fully use sunlight and provide the driving force of charge separation. The composite photoanode (TiO/WO//Sb-SnO @Si PVC) has a ClO• generation rate of 260% compared with the back-to-bake assembly way. In addition, the electrons transfer to the NiFe LDH@Cu NWs/CF cathode for rapid H production by the constructed photoelectric catalytic (PEC) cell without applied external biasing potential, in which the H production yield reaches 84.55 μmol h with 25% improvement of the urine denitrification rate. The superior performance and long-term stability of PEC cell provide an effective and promising method for denitrification and H generation.