Cobalt Pyrene‐Quaterpyridine Molecular Complex Immobilized on Functionalized Multi‐Walled Carbon Nanotubes as a Robust Hybrid Catalyst for Efficient Electrochemical Reduction of CO ₂

Abstract Molecular complexes immobilized on conductive carbon supports is a promising strategy for designing efficient electrocatalysts of CO ₂ reduction reaction (CO ₂ RR). However, most immobilized catalysts suffer from low catalytic activity and durability due to weak catalyst‐support interactions. Herein, modifications of Co quaterpyridine complex (Coqpy) with a pyrene group and multi‐walled carbon nanotubes (MWCNT) with carboxyl or amide groups have been made, resulting in a highly efficient and stable hybrid catalyst. The carboxyl groups on MWCNT can effectively bind to Co centers by axial coordination; which allow for loading more electroactive Co complex, facilitate interfacial electron transfer, and lower the energy barrier for CO ₂ RR. A 2.6‐fold increase in CO yield and a higher Faradaic efficiency (97.5% vs 83.6% at 423 mV overpotential) are obtained compared with the hybrid catalyst without carboxyl group. While, the pyrene group induced more substantial π–π interactions, leading to an enhanced electronic coupling between MWCNT and Coqpy, and enhanced hybrid stability, resulting in a ≈ 4.4‐fold higher CO turnover frequency than Coqpy. Overall, the outstanding performance of the modified hybrid catalyst (turnover number up to 570000, Faradaic efficiency close to 100%) provides new mechanistic insights and design strategy for efficient and durable CO ₂ RR based on heterogenized molecular catalysts.