Collective Effect in Hierarchical Porous MOFs Combining Single Atoms and Nanoparticles for Enhanced CO2 Photoreduction to CO

Reasonable construction of atomically accurate photocatalysts is the key to building efficient photocatalytic systems. Herein, we propose a collective effects strategy that enables the consolidation of both cobalt single atoms (Co_SAs) and nickel nanoparticles (Ni_NPs) in hierarchical porous MOFs for the foundational features for the preparation of high-performance photocatalysts. Among them, the optimal sample Co_SAs/Al-bpydc/Ni_NPs achieved a CO generation rate of 12.8 mmol·g^–1·h^–1 and selectivity of 91% in 4 h. According to the experiment characterizations and theoretical simulations, we found that Co_SAs facilitate CO₂ adsorption and activation, while Ni_NPs promote hydrogen spillover and transfer of hydrogen protons to Co_SAs, highlighting the collective effect of the catalytic system with multiple active sites. Most importantly, as a proof of concept, this performance enhancement strategy can also be applied to other hierarchically porous MOF photocatalysts, such as Al-bpdc, DUT-4, and UiO-67. This work provides new insight into the development of performance optimization of CO₂ conversion photocatalysts through the ingenious design of collective catalytic sites.