Junction Engineering for Photocatalytic and Photoelectrocatalytic CO 2 Reduction

Artificial photosynthesis of clean fuels shows fascinating prospects for solving the energy crisis and environmental pollution. However, the solar conversion efficiency is too low to fulfill industrialization requirements, which is confined by the poor photon utilization, severe recombination of electrons and holes, and insufficient reactive sites. Fortunately, junction engineering displays outstanding performance in conquering the aforementioned problems. Herein, an updated fundamental understanding of various junction engineering for enhancing the efficiency, selectivity, and stability of solar‐driven CO2 reduction is provided. The recent progresses of heterojunctions, homojunctions, and multijunctions for photocatalytic (PC) and photoelectrochemical (PEC) CO2 reduction are focused on, especially their essential roles in facilitating the key PC or PEC processes, including charge separation and transfer, adsorption and activation of CO2, and desorption of products, which may provide an interactively referential development pathway for CO2 photoreduction. Finally, an outlook on the current challenges and perspectives of junction engineering design of photocatalysts for solar‐driven CO2 reduction is provided.