Single-Atom Metal Anchored Zr 6 -Cluster-Porphyrin Framework Hollow Nanocapsules with Ultrahigh Active-Center Density for Electrocatalytic CO 2 Reduction

Designing earth-abundant electrocatalysts toward highly efficient CO reduction has significant importance to decrease the global emission of greenhouse gas. Herein, we propose an efficient strategy to anchor non-noble metal single atoms on Zr -cluster-porphyrin framework hollow nanocapsules with well-defined and abundant metal-N porphyrin sites for efficient electrochemical CO reduction. Among different transition metal single atoms (Mn, Fe, Co, Ni, and Cu), Co single-atom anchored Zr -cluster-porphyrin framework hollow nanocapsules demonstrated the highest activity and selectivity for CO production. The rich Co-N active centers and hierarchical porous structure contribute to enhanced CO adsorption capability and moderate binding strength of reaction intermediates, thus facilitating *CO desorption and CO -to-CO conversion. The Co-anchored nanocapsules maintain high efficiency and well-preserved stability during long-term electrocatalysis tests. Moreover, the Co-anchored nanocapsules exhibit a remarkable solar-to-CO energy conversion efficiency of 12.5% in an integrated solar-driven CO reduction/O evolution electrolysis system when powered by a custom large-area [Cs (FA MA ) ]Pb (I Br ) -based perovskite solar cell.