Trinuclear copper supramolecular frameworks for boosting the electrocatalytic reduction of CO2 to C3 products

Abstract

The electrocatalytic reduction of CO₂ to liquid fuels provides a compelling pathway towards the storage and conversion of renewable energy. However, designing suitable catalysts to improve liquid product selectivity remains challenging. Herein, the trinuclear copper supramolecular frameworks Cu₃–HCOO and Cu₃–SO₄ were designed and constructed by an aldehyde amine condensation reaction and a metal self-assembly reaction, and they contained three Cu active center sites and had the ability to generate multi-carbon products in the electrochemical CO₂ reduction reaction (CDRR). Trinuclear molecular Cu₃–SO₄ exhibited 5.57% n-propanol faradaic efficiency (FE(n-PrOH)) in the electrochemical CDRR process. By replacing the anionic groups on Cu sites, Cu₃–HCOO further exhibited an FE(n-PrOH) of 6.76%. This efficiency of C₃ product generation remains at a moderate level compared to that of C₁/C₂, and it still presents a challenging reaction. In addition, in situ FTIR and ¹³C isotope results further indicated that the HCOO group on trinuclear Cu promoted the generation of CO and the subsequent C–C coupling process, thereby achieving the generation of n-PrOH. Furthermore, theoretical calculations confirmed the thermodynamic feasibility of Cu₃–HCOO catalyzing the conversion of CO₂ to n-PrOH. This work provides new ideas for the design of polynuclear metal molecule catalysts and their application in CO₂ reduction, offering new insights for the development of multi-carbon product systems.