Photoelectrocatalytic (PEC) water splitting for H₂ production and CO₂ reduction for fuel production are important ways for solar energy conversion and utilization. However, the PEC efficiency is limited by problems such as poor light absorption, high overpotential and sluggish kinetics of surface reaction, and serious recombination of photogenerated carriers. Herein, we describe the principles of PEC water splitting and CO₂ reduction, recent progress and strategies on increasing the PEC efficiency, including enhancing light absorption via energy band engineering, morphology control and sensitizing strategy, promoting surface reaction via loading cocatalyst, enhancing charge separation and transfer via introducing local dipole and heterojunction electric field, morphology control, interface engineering, etc.

photoelectrocatalytic water splitting  /  CO₂ reduction  /  light absorption  /  charge separation  /  cocatalyst  /  interface