Enhanced Nanoconfinement of Copper-Organic Interfaces within Phthalocyanine Frameworks for Selective Electroreduction of CO to Acetate

Abstract

Acetate is an essential raw material in the chemical industry, supporting sustainable processes and efficient carbon utilization, driving interest in electrochemical CO-to-acetate conversion. However, this process is limited by catalyst instability and the complexity of the reaction pathway, making precise control difficult. Herein, we engineer nanoconfined copper-organic interfaces within a series of nucleophilic substituted heterocyclic copper phthalocyanine covalent organic frameworks (CuPc-COFs) with AA’ stacking configuration to selectively steer CO electroreduction toward acetate. This architecture stabilizes low-coordination Cu clusters─generated via partial reduction of phthalocyanine Cu sites─and fosters synergistic CuPc-Cu cluster interactions, creating an active interfacial microenvironment that enhances acetate selectivity. The optimized CuPc-COF achieves a Faradaic efficiency (FE) of 53.5% for acetate at −0.9 V vs RHE. Operando X-ray absorption spectroscopy (XAS) confirms the in situ formation of highly reactive copper-organic interfaces, while in situ FTIR spectroscopy and DFT calculations reveal that low-coordinated Cu clusters strengthen *CO bridge adsorption (*CO_B) and promote *COCO dimerization. Additionally, heterocyclic linkers provide electron donation, stabilizing the Cu clusters and improving the structural integrity. This work elucidates the critical role of nanoconfined interface engineering in C–C coupling and establishes a design paradigm for advanced CO electroreduction catalysts.