Metal halide perovskites for CO₂ photoreduction: recent advances and future perspectives

CO₂ emission has inarguably become one of the greatest challenges ever faced by mankind since industrial revolution. Techniques aiming at capture, storage and utilization of CO₂ have attracted tremendous interest from both industry and academia. Thermal, electrical and photo-catalytic conversion of CO₂ to value-added chemicals and fuels is the most well-known approach for CO₂ utilization. In particular, photocatalytic reduction of CO₂ (CO₂PR) directly employs solar energy as the driving force to activate CO₂, yielding various products including CO, CH₄ and C₂₊ hydrocarbons. CO₂PR, which mimics photosynthesis occurring in nature, is also regarded as “artificial photosynthesis” and is believed to be a promising approach toward carbon neutral economy. Recently, metal halide perovskites (MHPs) have emerged as potential photocatalysts for CO₂PR, owing to their flexible structures and excellent photoelectronic properties. This review presents a comprehensive overview of state-of-the-art developments in MHP-based catalysts for CO₂PR. Firstly, the crystal structures and photoelectric properties of MHPs are reviewed in detail, as they are the key factors determining CO₂PR catalytic performance. Secondly, design strategies to promote the catalytic efficiency of CO₂PR to CO conversion for both lead-based and lead-free MHPs are discussed, including morphological modifications, co-catalyst modifications, ion doping and crystal plane modifications. Thirdly, this review addresses MHP-based CO₂PR to CH₄ and C₂₊ products, with special emphasis on approaches adopted to promote specific product selectivity. Lastly, our perspectives and opinions are given on current research challenges and future directions for CO₂PR, which we consider are critical for its industrialization.