Imidazolium-Functionalized Cationic Covalent Triazine Frameworks Stabilized Copper Nanoparticles for Enhanced CO2 Electroreduction

The highly selective production of reduced multicarbon products with long-term durability for CO2 electroreduction reaction (CO2RR) using clean and renewable electricity is currently a major challenge. Copper nanoparticles (Cu NPs) are exceptionally advantageous for CO2RR to yield multielectron transfer chemical products such as ethylene and ethanol. However, Cu NPs for CO2RR generally require high overpotential to produce multiple electron transfer C2+ products with poor stability. Herein, an imidazolium-functionalized covalent triazine framework (ICTF) stabilized Cu NPs (Cu/ICTF) for the enhanced CO2RR to produce ethylene is reported. The imidazolium groups in the cationic ICTF not only can enhance CO2 capture capacity and lower the energetic barrier to activate CO2, but also the in situ formed N-heterocyclic carbenes (NHC) could stabilize Cu NPs to prevent their deactivation. Thus, the Cu/ICTF demonstrated higher selectivity (35 %) for the electroreduction of CO2 to ethylene with larger partial current density of ethylene (4.14 mA cm(-2)) over the unmodified neutral CTF stabilized Cu NPs (Cu/CTF) with 29 % Faradaic efficiency (FE) of ethylene and current density of 3.69 mA cm(-2). Moreover, the active sites could be stabilized by the in situ produced NHC in ICTF and the current density and C2H4 FE of Cu/ICTF50 were almost maintained after 10 h continuous electrolysis experiment, while the C2H4 FE of Cu/CTF50 were lost ca. 42 % of its original value after 7 h. This strategy provides a facile approach to stabilize active sites for CO2RR and may bring new inspiration to apply in energy storage and conversion.