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A Nickel Dithiolate Water Reduction Catalyst Providing Ligand‐Based Proton‐Coupled Electron‐Transfer Pathways
Author(s) -
Koshiba Keita,
Yamauchi Kosei,
Sakai Ken
Publication year - 2017
Publication title -
angewandte chemie international edition
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 5.831
H-Index - 550
eISSN - 1521-3773
pISSN - 1433-7851
DOI - 10.1002/anie.201700927
Subject(s) - catalysis , nickel , faraday efficiency , electron transfer , chemistry , hydrogenase , electrochemistry , proton coupled electron transfer , ligand (biochemistry) , electrolysis of water , redox , electrolysis , bulk electrolysis , electrocatalyst , photochemistry , proton , inorganic chemistry , electrode , cyclic voltammetry , organic chemistry , biochemistry , receptor , electrolyte , physics , quantum mechanics
A nickel pyrazinedithiolate ([Ni(dcpdt) 2 ] 2− ; dcpdt=5,6‐dicyanopyrazine‐2,3‐dithiolate), bearing a NiS 4 core similar to the active center of [NiFe] hydrogenase, is shown to serve as an efficient molecular catalyst for the hydrogen evolution reaction (HER). This catalyst shows effectively low overpotentials for HER (330–400 mV at pH 4–6). Moreover, the turnover number of catalysis reaches 20 000 over the 24 h electrolysis with a high Faradaic efficiency, 92–100 %. The electrochemical and DFT studies reveal that diprotonated one‐electron‐reduced species (i.e., [Ni II (dcpdt)(dcpdtH 2 )] − or [Ni II (dcpdtH) 2 ] − ) forms at pH<6.4 via ligand‐based proton‐coupled electron‐transfer (PCET) pathways, leading to electrocatalytic HER without applying the highly negative potential required to generate low‐valent nickel intermediates. This is the first example of catalysts exhibiting such behavior.