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Electrocatalytic H 2 Evolution by the Co‐Mabiq Complex Requires Tempering of the Redox‐Active Ligand
Author(s) -
Tok G. Ceren,
Freiberg Anna T. S.,
Gasteiger Hubert A.,
Hess Corinna R.
Publication year - 2019
Publication title -
chemcatchem
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.497
H-Index - 106
eISSN - 1867-3899
pISSN - 1867-3880
DOI - 10.1002/cctc.201900953
Subject(s) - chemistry , redox , cyclic voltammetry , catalysis , electrocatalyst , ligand (biochemistry) , protonation , photochemistry , electrochemistry , hydride , inorganic chemistry , bulk electrolysis , non innocent ligand , combinatorial chemistry , electrode , hydrogen , organic chemistry , ion , biochemistry , receptor
H 2 is a promising fuel for sustainable energy conversion and storage. The development of effective earth abundant H 2 evolution catalysts is integral to advancing hydrogen‐based technologies. H 2 evolution by molecular complexes classically involves the formation of metal hydride intermediates. Recently, the use of redox‐active ligands has emerged as an alternate strategy for electron and proton storage. Herein, we examine the electrocatalytic behavior of [Co II (Mabiq)(THF)](PF 6 ) ( Co Mbq ), containing a redox‐active macrocyclic ligand, in acidic, organic media (using para ‐cyanoanilinium ( p CA) as the proton source). Cyclic voltammetry (CV) and Rotating Ring Disk Electrode (RRDE) voltammetry evidence a pre‐catalytic process that leads to the formation of a protonated, two‐electron reduced intermediate. This species evolves H 2 at potentials negative of −1.1 V Fc , as confirmed by On‐line Electrochemical Mass Spectrometry (OEMS). OEMS results further reveal a catalyst deactivation pathway. The electrochemical data denote the involvement of the redox‐active Mabiq ligand in the hydrogen evolution reaction (HER), with implications for the use of such scaffolds in electrocatalytic complexes.