Atomically Dispersed High-Density Al-N4 Sites in Porous Carbon for Efficient Photodriven CO2 Cycloaddition.

Highly active catalysts that can directly utilize renewable energy (e.g., solar energy) are desirable for CO2 value-added processes. Herein, aiming at improving the efficiency of photodriven CO2 cycloaddition reactions, a catalyst composed of porous carbon nanosheets enriched with a high loading of atomically dispersed Al atoms (≈14.4 wt%, corresponding to an atomic percent of ≈7.3%) coordinated with N (AlN4 motif, Al-N-C catalyst) via a versatile molecule-confined pyrolysis strategy is reported. The performance of the Al-N-C catalyst for catalytic CO2 cycloaddition under light irradiation (≈95% conversion, reaction rate = 3.52 mmol g-1 h-1 ) is significantly superior to that obtained under a thermal environment (≈57% conversion, reaction rate = 2.11 mmol g-1 h-1 ). Besides the efficient photothermal conversion induced by the carbon matrix, both experimental and theoretical analysis reveal that light irradiation favors the photogenerated electron transfer from the semiconductive Al-N-C catalyst to the epoxide reactant, facilitating the formation of a ring-opened intermediate through the rate-limiting step. This study not only provides an advanced Al-N-C catalyst for photodriven CO2 cycloaddition, but also furnishes new insight for the rational design of superior photocatalysts for diverse heterogeneous catalytic reactions in the future.