Metal-Organic Frameworks for Gas-Solid Reactive Carbon Dioxide Capture – Photo/Thermochemical Routes

Abstract

Metal-organic frameworks (MOFs) are customizable adsorbents with demonstrated value for point-source and direct air capture of carbon dioxide (CO₂). Simultaneously, MOFs are emerging CO₂ reduction catalysts. Combining these independent pillars of success leads to the central focus of our review: the application of MOFs for reactive carbon capture (RCC), a process that eliminates intermediate separation, concentration, and transportation of CO₂ from the point of capture to the reactor. In the context of the present review, we consider a gas-solid RCC process where in one step, CO₂ is loaded on the material and in a second step, a co-reactant is fed to the reactor while energy in the form of heat or light stimulates product formation. Gas-solid RCC on pristine MOFs remains underexplored when compared with post-synthetically modified MOFs, amine-grafted frameworks, and solution-phase systems. This review critically assesses the dual functionality (capture and conversion) of MOFs, emphasizing their structural tunability, porosity, and photo/thermal catalytic activity. We systematically discuss central features, including CO₂ adsorption, thermochemical and photochemical CO₂ reduction pathways, and existing barriers to MOF RCC. We highlight specific features essential to RCC, including CO₂ chemisorption, band-gap modulation, and charge-transfer mechanisms for light-driven CO₂ reduction, and hydrogen/water activation pathways on MOFs. Finally, recent trends, challenges, and prospects in MOF design for RCC are discussed, offering a critical evaluation of their advantages, limitations, and potential for integrated RCC.