Cobalt phthalocyanine-based conjugated polymer as efficient and exclusive electrocatalyst for CO2 reduction to ethanol
Dong Jiang, Ran Bu, Wei Xia, Yichen Hu, Mengchen Zhou, En‐Qing Gao, Toru Asahi, Yusuke Yamauchi, Jing Tang
Abstract
Electrocatalytic conversion of carbon dioxide to high value-added chemicals is a promising method for solving the energy crisis and global warming. Electrochemical active metal-containing conjugated polymers have been widely studied for heterogeneous carbon dioxide reduction. In the present contribution, we designed and synthesized a stable cobalt phthalocyanine-based conjugated polymer, named CoPPc-TFPPy-CP, and also explored its electrocatalytic application in carbon dioxide reduction to liquid products in an aqueous solution. In the catalyst, cobalt phthalocyanine acts as building blocks connected with 1,3,6,8-tetrakis(4-formyl phenyl)pyrenes via imine-linkages, leading to mesoporous formation polymers with the pore size centered at 4.1 nm. And the central cobalt atoms shifted to a higher oxidation state after condensation. With these chemical and structural natures, the catalyst displayed a remarkable electrocatalytic CO2 reduction performance with an ethanol Faradaic efficiency of 43.25% at −1.0 V vs RHE. While at the same time, the electrochemical reduction process catalyzed by cobalt phthalocyanine produced only carbon monoxide and hydrogen. To the best of our knowledge, CoPPc-TFPPy-CP is the first example among organic polymers and metal-organic frameworks that produces ethanol from CO2 with a remarkable selectivity.