Copper(i) and cobalt(ii) frameworks with a tetraphenylethene–imidazole ligand for the electroreduction of CO2 to CH4†

Abstract

Targeted development of crystalline materials for the CO₂ reduction reaction (CO₂RR) is currently a hot topic. Copper is a common electrocatalyst for the reduction of CO₂ to CH₄. In this study, two new MOFs [Cu(TIPE)_0.5](ClO₄) (Cu-MOF) and [Co(TIPE)(TFA)₂]·2DMF (Co-MOF) (TIPE = 1,1,2,2-tetrakis(4-(imidazole-1-yl)phenyl)ethene, TFA = trifluoroacetate and DMF = N,N-dimethylformamide) were synthesized. Crystallographic analysis shows that Cu-MOF and Co-MOF are different 2D networks. Interestingly, Cu-MOF can serve as an efficient electrocatalyst for CO₂ conversion to CH₄, while the Co-MOF is not suitable for the electrocatalytic CO₂RR due to its low stability. In 1 M KOH electrolyte, Cu-MOF exhibits high performance for the electrocatalytic reduction of CO₂ to CH₄ with a faradaic efficiency (FE) of 41.53% at a potential of −1.28 V vs. RHE. The high performance and stability may be caused by the framework structure leading to a large electrochemically active surface area and fast charge transfer kinetics. This work offers an approach to design and construct CO₂ electroreduction catalysts and viable solutions to energy and environmental issues caused by excessive CO₂ emission.