Basic comprehension and recent trends in photoelectrocatalytic systems

Abstract

Photoelectrocatalysis (PEC) technology has emerged in the last few decades as an environmentally friendly technology with potentially improved performances with respect to conventional electrocatalysis (EC) and photocatalysis (PC). The combination of both light irradiation and electrochemical methods, together with different modification procedures of photocatalysts, can drastically improve the overall catalytic efficiency. This review article aims to provide an overview of the current state and future trends of PEC technology from different points of view including reactor configurations, materials and potential applications. A special emphasis is placed on the different types of material used in PEC and possible strategies for their upgrading, dealing with their morphology and/or composition modification. Indeed, in PC or PEC, the proper combination of photoactive and catalytic materials is one of the key features. On the other hand, we also highlight the different PEC processes that, from our point of view, are of special energy or environmental interest, including anodic reactions like oxygen evolution, hydrogen peroxide generation, organic molecule mineralization or selective oxidation, and cathodic reactions like hydrogen evolution, CO₂ reduction or N₂ fixation. Indeed, apart from water splitting, other interesting approaches are emerging by combining some of the above half-reactions, like artificial photosynthesis and the co-generation of H₂, and value-added chemicals from biomass valorization. We discuss the current state of each approach and the necessary progress for their further technological development.