Construction of Single-Atom Cobalt in Ordered Mesoporous Metal–Organic Frameworks for Boosting CO2 Conversion

Constructing single-atom transition-metal-implanted mesoporous metal-organic frameworks (MOFs) for CO2 conversion is of great importance for achieving carbon neutrality, yet remains a formidable challenge. This work presents a modular optimization of cerium-based metal-organic frameworks by incorporating Co single atoms with ordered mesopores (OMCU). These periodically arranged mesopores in OMCU were fabricated by synergistically combining the Hofmeister effect with a soft-template structure-oriented strategy. Mechanistic investigations reveal that the Co single atoms could not only accelerate photogenerated electron participation in CO2 conversion but also lower the energy barrier by promoting the formation of a new intermediate, *OCHO, along a specific reduction pathway, as directly observed by in situ Raman and operando ATR-IR spectroscopy. Density functional theory calculations corroborate that Co atoms favor the generation of *OCHO-related intermediates, omitting the high energy input for CO2·- formation and resulting in outstanding CO2 reduction performance, which is equivalent to a 10.84-fold enhancement in CO generation rate compared to that of the pristine MOF in the presence of TEA and bipyridinium ruthenium. This work provides an effective strategy through the construction of active cobalt sites within ordered mesoporous cerium-based MOFs for modulating the key intermediates in CO2 photoreduction.