Synchronous generation of H2O2 and high effective removal of inorganic arsenic/organoarsenic by visible light-driven cell

A Janus photocathode of asymmetric wettability with hydrophobic oxygen storage layer and hydrophilic catalyst layer was successfully fabricated by graphite felt (GF) polytetrafluoroethylene (PTFE)-hydrophobization and a subsequent hollow sphere NiFe2O4@ZnFe2O4 (NF@ZF) Z-scheme photocatalysts coating on the other side of GF. The designed Janus electrode showed significantly higher H2O2 production than hydrophilic (NF@ZF/GF) and hydrophobic (NF@ZF/PTFE/GF) electrodes, and achieved a higher faradaic efficiency of 72%, as well as a record H2O2 production rate of 255.9 mg·L-1∙h-1, while maintaining a stable photoelectrochemical performance for 9 h at 2.8 mA∙cm-2 in Na2SO4 solution. The two-electrode co-photoelectrolysis system by coupling the ORR with inorganic arsenic/organoarsenic oxidation can simultaneously produce H2O2 at Janus photocathode and As (V) at Fe anode under a low energy consumption (a cell voltage of only 0.7 V), respectively, and then the generated As (V) could be rapidly removed (above 93%) by adsorption onto Fe (III) (hydro)oxides.