Recent advances in photoelectrocatalysis for simultaneous water purification, energy generation or resource recovery

Serious water pollution and energy demand issues are driving the rapid development of several advanced technologies to purify wastewater, generate energy, and reduce waste in the context of sustainable economic growth. Herein, the application of photoelectrocatalysis (PEC) to wastewater treatment, with simultaneous production of either energy or high value-added products, and even with recovery of valuable resources, is reviewed. Specifically, multifunctional PEC systems include wastewater treatment, combined with either the production of H2, H2O2, CO2-derived chemicals, and power or the recovery of metal (e.g., Ag, Cu) and nonmetal (e.g., N, S) resources. The fundamentals of PEC process, the performance and selection of photoelectrodes, the mechanisms of different PEC applications and the construction of reactors are discussed. In addition, the critical challenges of PEC development in terms of system stability, energy consumption, and scale-up to practical applications are summarized. This review provides a comprehensive overview of multifunctional PEC systems in which reaction coupling allows achieving high-efficiency and low-energy consumption, with the ultimate goal of achieving a greener development.