Porphyrin-based metal-organic frameworks for photocatalytic carbon dioxide reduction: Current understanding and challenges

Photocatalytic carbon dioxide reduction reaction (CO₂RR) is a carbon-neutral strategy to address global energy use and its impact on climate. Metal oxide and metal chalcogenide catalysts are the most investigated catalysts for photocatalytic CO₂RR. Unfortunately, low CO₂ adsorption ability and limited active sites of metal oxide and metal chalcogenide catalysts for CO₂RR make them less competitive compared to their industrial counterparts. Inspired by applications of porphyrin-based metal-organic framework (MOF) catalysts for hydrogen evolution and photodynamic therapy, the investigations of these porphyrin-based MOFs, including pristine and composite porphyrin-based MOFs in photocatalytic CO₂RR, have attracted significant attention in the last five years due to their excellent CO₂ adsorption capacities, high porosity, high stability, exceptional optoelectronic properties, and multi-functionality. However, due to the difference in photocatalytic CO₂RR, several critical issues need to be addressed to achieve the rational design of advanced porphyrin-based MOF photocatalysts to improve activity, selectivity, and stability for CO₂RR. Here, we review recent developments in the field of porphyrin-based MOF CO₂RR photocatalysts, along with critical issues, challenges, and perspectives concerning porphyrin-based MOF catalysts for photocatalytic CO₂RR.