Electro-reduction of carbon dioxide at low over-potential at a metal-organic framework decorated cathode

Electrochemical reduction of carbon dioxide is a clean and attractive strategy for producing organic products but is hindered by the high negative potential required to activate CO₂. The authors report a copper electrode decorated with a porous metal–organic framework, [Cu₂(L)] (H₄L = 4,4',4",4''-(1,4-phenylenebis(pyridine-4,2,6-triyl))tetrabenzoic acid), prepared by ionic-liquid-templated electrosynthesis. This decorated electrode exhibits an onset potential of −1.45 V vs. Ag/Ag⁺ for CO₂ reduction to formic acid in an organic electrolyte, achieving a current density of 65.8 mA·cm⁻² at −1.8 V with a Faradaic efficiency of 90.5% to formic acid. EPR spectroscopy confirms the presence of structural defects comprising homogenously distributed, uncoupled Cu(II) centers generated by the templated electro-synthesis. These active sites promote catalytic performance, as supported by DFT calculations.

Xinchen Kang, Lili Li, Alena Sheveleva, Xue Han, Jiangnan Li, Lifei Liu, Floriana Tuna, Eric J. L. McInnes, Buxing Han, Sihai Yang, Martin Schröder