Defective materials for CO2 photoreduction: From C1 to C2+ products

Photocatalytic CO2 conversion to carbon-based products has been proven as a versatile method to manage carbon balance. Engineering defects into photocatalysts is an effective strategy to maneuver their performance for CO2 reduction. This critical review summarizes the advantages, state-of-the-art progress, remaining challenges, and perspectives regarding defective materials for CO2 photoreduction, especially based on two-dimensional materials. Different types of defects are employed to tailor the electronic structure, atomic coordination configuration, carrier concentration or electrical conductivity for CO2 photoreduction, namely anion vacancies, cation vacancies, vacancy pairs, planar defects and volume defects. The strategies for defect construction, defect identification are summarized. The key roles of various defects for CO2 photoreduction from various aspects are presented, such as light absorption and electronic structure, charge separation and transfer, reactant adsorption and activation, reaction energy barriers, reaction pathways. Especially, the CC coupling via defect engineering is highlighted, certainly shows greater potentiality for future CO2 photoreduction. Finally, major challenges and opportunities regarding the future exploration of defective materials for CO2 photoreduction are presented.