Single-Atom Metal Anchored Zr6-Cluster-Porphyrin Framework Hollow Nanocapsules with Ultrahigh Active-Center Density for Electrocatalytic CO2 Reduction.

Abstract

Designing earth-abundant electrocatalysts toward highly efficient CO2 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 Zr6-cluster-porphyrin framework hollow nanocapsules with well-defined and abundant metal-N4 porphyrin sites for efficient electrochemical CO2 reduction. Among different transition metal single atoms (Mn, Fe, Co, Ni, and Cu), Co single-atom anchored Zr6-cluster-porphyrin framework hollow nanocapsules demonstrated the highest activity and selectivity for CO production. The rich Co-N4 active centers and hierarchical porous structure contribute to enhanced CO2 adsorption capability and moderate binding strength of reaction intermediates, thus facilitating *CO desorption and CO2-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 CO2 reduction/O2 evolution electrolysis system when powered by a custom large-area [Cs0.05(FA0.85MA0.15)0.95]Pb0.9(I0.85Br0.15)3-based perovskite solar cell.