Review on Photogenerated Hole Modulation Strategies in Photoelectrocatalysis for Solar Fuel Production

Photoelectrocatalytic (PEC) technique provides a clean, low-cost, and environmental-friendly route with great potential for addressing energy crisis mainly through water splitting and CO2 reduction by utilizing solar energy. In general, it is favorable for the added external electric field to greatly modulate the photogenerated electrons in PEC process. However, it is a rate-determining step as another half-reaction for the photogenerated hole to induce water oxidation since it is usually involved with 4 electrons for O-2 evolution. Thus, it is highly desired to develop feasible strategies to modulate photogenerated hole for efficient solar-to-energy conversion. Unfortunately, it is frequently neglected compared to the electron regulation. Obviously, it is much meaningful to develop new efficient strategies for photogenerated hole modulation, along with to review recent developments. Herein, this minireview summarizes the recent developments of photoexcited hole modulation for PEC process to nanosized semiconductors, and it is highlighted for the strategies successfully developed in our group in recent years, mainly including surface polarization by modifying inorganic acids and halogen anions, and non-metallic element doping. Moreover, related conclusions and several outlooks are put forward.