Semiconductor Quantum Dots: An Emerging Candidate for CO2 Photoreduction

As one of the most critical approaches to resolve the energy crisis and environmental concerns, carbon dioxide (CO2 ) photoreduction into value-added chemicals and solar fuels (for example, CO, HCOOH, CH3 OH, CH4 ) has attracted more and more attention. In nature, photosynthetic organisms effectively convert CO2 and H2 O to carbohydrates and oxygen (O2 ) using sunlight, which has inspired the development of low-cost, stable, and effective artificial photocatalysts for CO2 photoreduction. Due to their low cost, facile synthesis, excellent light harvesting, multiple exciton generation, feasible charge-carrier regulation, and abundant surface sites, semiconductor quantum dots (QDs) have recently been identified as one of the most promising materials for establishing highly efficient artificial photosystems. Recent advances in CO2 photoreduction using semiconductor QDs are highlighted. First, the unique photophysical and structural properties of semiconductor QDs, which enable their versatile applications in solar energy conversion, are analyzed. Recent applications of QDs in photocatalytic CO2 reduction are then introduced in three categories: binary II-VI semiconductor QDs (e.g., CdSe, CdS, and ZnSe), ternary I-III-VI semiconductor QDs (e.g., CuInS2 and CuAlS2 ), and perovskite-type QDs (e.g., CsPbBr3 , CH3 NH3 PbBr3 , and Cs2 AgBiBr6 ). Finally, the challenges and prospects in solar CO2 reduction with QDs in the future are discussed.