Defective materials for CO 2 photoreduction: From C 1 to C 2+ products

Photocatalytic CO 2 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 CO 2 reduction. This critical review summarizes the advantages, state-of-the-art progress, remaining challenges, and perspectives regarding defective materials for CO 2 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 CO 2 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 CO 2 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 C C coupling via defect engineering is highlighted, certainly shows greater potentiality for future CO 2 photoreduction. Finally, major challenges and opportunities regarding the future exploration of defective materials for CO 2 photoreduction are presented.