Volume 129, Issue 15 pp. 4311-4315
Zuschrift

A Nickel Dithiolate Water Reduction Catalyst Providing Ligand-Based Proton-Coupled Electron-Transfer Pathways

Keita Koshiba

Keita Koshiba

Department of Chemistry, Faculty of Science, Kyushu University, Motooka 744, Nishi-ku, Fukuoka, 819-0395 Japan

International Institute for Carbon-Neutral Energy Research (WPI-I2CNER), Kyushu University, Japan

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Dr. Kosei Yamauchi

Corresponding Author

Dr. Kosei Yamauchi

Department of Chemistry, Faculty of Science, Kyushu University, Motooka 744, Nishi-ku, Fukuoka, 819-0395 Japan

International Institute for Carbon-Neutral Energy Research (WPI-I2CNER), Kyushu University, Japan

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Prof. Ken Sakai

Corresponding Author

Prof. Ken Sakai

Department of Chemistry, Faculty of Science, Kyushu University, Motooka 744, Nishi-ku, Fukuoka, 819-0395 Japan

International Institute for Carbon-Neutral Energy Research (WPI-I2CNER), Kyushu University, Japan

Center for Molecular Systems (CMS), Kyushu University, Japan

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First published: 09 March 2017
Citations: 23

Abstract

A nickel pyrazinedithiolate ([Ni(dcpdt)2]2−; dcpdt=5,6-dicyanopyrazine-2,3-dithiolate), bearing a NiS4 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., [NiII(dcpdt)(dcpdtH2)] or [NiII(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.

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