Confinement Effects in Well-Defined Metal–Organic Frameworks (MOFs) for Selective CO(2) Hydrogenation: A Review

Decarbonization has become an urgent affair to restrain global warming. CO(2) hydrogenation coupled with H(2) derived from water electrolysis is considered a promising route to mitigate the negative impact of carbon emission and also promote the application of hydrogen. It is of great significance to develop catalysts with excellent performance and large-scale implementation. In the past decades, metal–organic frameworks (MOFs) have been widely involved in the rational design of catalysts for CO(2) hydrogenation due to their high surface areas, tunable porosities, well-ordered pore structures, and diversities in metals and functional groups. Confinement effects in MOFs or MOF-derived materials have been reported to promote the stability of CO(2) hydrogenation catalysts, such as molecular complexes of immobilization effect, active sites in size effect, stabilization in the encapsulation effect, and electron transfer and interfacial catalysis in the synergistic effect. This review attempts to summarize the progress of MOF-based CO(2) hydrogenation catalysts up to now, and demonstrate the synthetic strategies, unique features, and enhancement mechanisms compared with traditionally supported catalysts. Great emphasis will be placed on various confinement effects in CO(2) hydrogenation. The challenges and opportunities in precise design, synthesis, and applications of MOF-confined catalysis for CO(2) hydrogenation are also summarized.