Designing N-Confused Metalloporphyrin-Based Covalent Organic Frameworks for Enhanced Electrocatalytic Carbon Dioxide Reduction.

Electrochemical conversion of carbon dioxide (CO ) into value-added products is promising to alleviate greenhouse gas emission and energy demands. Metalloporphyrin-based covalent organic frameworks (MN -Por-COFs) provide a platform for rational design of electrocatalyst for CO reduction reaction (CO RR). Herein, through systematic quantum-chemical studies, the N-confused metallo-Por-COFs are reported as novel catalysts for CO RR. For MN -Por-COFs, among the ten 3d metals, M = Co/Cr stands out in catalyzing CO RR to CO or HCOOH; hence, N-confused Por-COFs with Co/CrN C and Co/CrN C centers are designed. Calculations indicate CoN C -Por-COFs exhibit lower limiting potential (-0.76 and -0.60 V) for CO -to-CO reduction than its parent CoN -Por-COFs (-0.89 V) and make it feasible to yield deep-reduction degree C products CH OH and CH . Electronic structure analysis reveals that substituting CoN to CoN C /CoN C increases the electron density on Co-atom and raises the d-band center, thus stabilizing the key intermediates of the potential determining step and lowering the limiting potential. For similar reason, changing the core from CrN to CrN C /CrN C lowers the limiting potential for CO -to-HCOOH reduction. This work predicts N-confused Co/CrN C -Por-COFs to be high-performance CO RR catalyst candidates. Inspiringly, as a proof-of-concept study, it provides an alternative strategy for coordination regulation and theoretical guidelines for rational design of catalysts.