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Hydrogen Evolution Electrocatalysis with a Molecular Cobalt Bis(alkylimidazole)methane Complex in DMF: a Critical Activity Analysis
Author(s) -
Vos Sander D.,
Otten Maartje,
Wissink Tim,
Broere Daniël L. J.,
Hensen Emiel J. M.,
Klein Gebbink Robertus J. M.
Publication year - 2022
Publication title -
chemsuschem
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.412
H-Index - 157
eISSN - 1864-564X
pISSN - 1864-5631
DOI - 10.1002/cssc.202201308
Subject(s) - overpotential , electrocatalyst , cobalt , catalysis , chemistry , electrolysis , glassy carbon , bulk electrolysis , faraday efficiency , cyclic voltammetry , inorganic chemistry , methane , voltammetry , electrode , electrochemistry , organic chemistry , electrolyte
[Co(HBMIM Ph2 ) 2 ](BF 4 ) 2 ( 1 ) [HBMIM Ph2 =bis(1‐methyl‐4,5‐diphenyl‐1 H ‐imidazol‐2‐yl)methane] was investigated for its electrocatalytic hydrogen evolution performance in DMF using voltammetry and during controlled potential/current electrolysis (CPE/CCE) in a novel in‐line product detection setup. Performances were benchmarked against three reported molecular cobalt hydrogen evolution reaction (HER) electrocatalysts, [Co(dmgBF 2 ) 2 (solv) 2 ] ( 2 ) (dmgBF 2 =difluoroboryldimethylglyoximato), [Co(TPP)] ( 3 ) (TPP=5,10,15,20‐tetraphenylporphyrinato), and [Co(bapbpy)Cl](Cl) ( 4 ) [bapbpy=6,6′‐bis‐(2‐aminopyridyl)‐2,2′‐bipyridine], showing distinct performances differences with 1 being the runner up in H 2 evolution during CPE and the best catalyst in terms of overpotential and Faradaic efficiency during CCE. After bulk electrolysis, for all of the complexes, a deposit on the glassy carbon electrode was observed, and post‐electrolysis X‐ray photoelectron spectroscopy (XPS) analysis of the deposit formed from 1 demonstrated only a minor cobalt contribution (0.23 %), mainly consisting of Co 2+ . Rinse tests on the deposits derived from 1 and 2 showed that the initially observed distinct activity was (partly) preserved for the deposits. These observations indicate that the molecular design of the complexes dictates the features of the formed deposit and therewith the observed activity.