Photoelectrocatalytic principles for meaningfully studying photocatalyst properties and photocatalysis processes: From fundamental theory to environmental applications

Photocatalysis is critically important for environmental remediation and renewable energy technologies. The ability to objectively characterize photocatalyst properties and photocatalysis processes is paramount for meaningful performance evaluation and fundamental studies to guide the design and development of high-performance photocatalysts and photocatalysis systems. Photocatalysis is essentially an electron transfer process, and photoelectrocatalysis (PEC) principles can be used to directly quantify transferred electrons to determine the intrinsic properties of photocatalysts and photocatalysis processes in isolation, without interference from counter reactions due to physically separated oxidation and reduction half-reactions. In this review, we discuss emphatically the PEC-based principles for characterizing intrinsic properties of photocatalysts and important processes of photocatalysis, with a particular focus on their environmental applications in the degradation of pollutants, disinfection, and detection of chemical oxygen demand (COD). An outlook towards the potential applications of PEC technique is given.