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Electrocatalysts Derived from Copper Complexes Transform CO into C 2+ Products Effectively in a Flow Cell
Author(s) -
Ren Shaoxuan,
Zhang Zishuai,
Lees Eric W.,
Fink Arthur G.,
Melo Luke,
Hunt Camden,
Dvorak David J.,
Yu Wu Wen,
Grant Edward R.,
Berlinguette Curtis P.
Publication year - 2022
Publication title -
chemistry – a european journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.687
H-Index - 242
eISSN - 1521-3765
pISSN - 0947-6539
DOI - 10.1002/chem.202200340
Subject(s) - catalysis , copper , chemistry , electrolysis , bulk electrolysis , inorganic chemistry , electrocatalyst , faraday efficiency , electrolyte , electrochemistry , metal , hydroxide , chemical engineering , electrode , organic chemistry , engineering
Electrochemical reactors that electrolytically convert CO 2 into higher‐value chemicals and fuels often pass a concentrated hydroxide electrolyte across the cathode. This strongly alkaline medium converts the majority of CO 2 into unreactive HCO 3 − and CO 3 2− byproducts rather than into CO 2 reduction reaction (CO2RR) products. The electrolysis of CO (instead of CO 2 ) does not suffer from this undesirable reaction chemistry because CO does not react with OH − . Moreover, CO can be more readily reduced into products containing two or more carbon atoms (i. e., C 2+ products) compared to CO 2 . We demonstrate here that an electrocatalyst layer derived from copper phthalocyanine ( CuPc ) mediates this conversion effectively in a flow cell. This catalyst achieved a 25 % higher selectivity for acetate formation at 200 mA/cm 2 than a known state‐of‐art oxide‐derived Cu catalyst tested in the same flow cell. A gas diffusion electrode coated with CuPc electrolyzed CO into C 2+ products at high rates of product formation (i. e., current densities ≥200 mA/cm 2 ), and at high faradaic efficiencies for C 2+ production ( FE C2+ ; >70 % at 200 mA/cm 2 ). While operando Raman spectroscopy did not reveal evidence of structural changes to the copper molecular complex, X‐ray photoelectron spectroscopy suggests that the catalyst undergoes conversion to a metallic copper species during catalysis. Notwithstanding, the ligand environment about the metal still impacts catalysis, which we demonstrated through the study of a homologous CuPc bearing ethoxy substituents. These findings reveal new strategies for using metal complexes for the formation of carbon‐neutral chemicals and fuels at industrially relevant conditions.