Electrocatalytic H2 Generation from Water Relying on Cooperative Ligand Electron Transfer in "PN3P" Pincer‐Supported NiII Complexes. Issue 54 (20th August 2021)

• Record Type: Journal Article
• Authors: Norouziyanlakvan, Somayeh; Rao, Gyandshwar Kumar; Ovens, Jeffrey; Gabidullin, Bulat; Richeson, Darrin
• Is Part Of: Chemistry. Volume 27:Issue 54(2021)
• Page Start: 13518
• Page End: 13522
• Publication Date: 2021-08-20
• Subjects: Electrocatalysis -- hydrogen production -- nickel -- reduction of water; Chemistry -- Periodicals; 540
• DOI: 10.1002/chem.202102031
• Languages: English
• ISSNs: 0947-6539

Abstract

Abstract: Water is the most sustainable source for H2 production, and the efficient electrocatalytic production of H2 from mixed water/acetonitrile solutions by using two new air‐stable nickel(II) pincer complexes, [Ni(κ 3 ‐2, 6‐{Ph2 PNR}2 (NC5 H3 )Br2 ] (R=H I, Me II ) is reported. Hydrogen generation from H2 O/CH3 CN solutions is initiated at −2 V against Fc +/0, and bulk electrocatalysis studies showed that the catalyst functions with an excellent Faradaic efficiency and a turnover frequency of 160 s −1 . A DFT computational investigation of the reduction behavior of I and II revealed a correlation of H2 formation with charge donation from electrons originating in a reduced ligand‐localized orbital. As a result, these catalysts are proposed to proceed by a novel mechanism involving electron/proton transfer between a Ni 0I species bonded to an anionic PN 3 P ligand ("L − /Ni 0I ") and a Ni I ‐hydride ("Ni−H"). Furthermore, these catalysts are able to reduce phenol and acetic acid, more active proton sources, at lower potentials that correlate with the substrate p K a . Abstract : Towards sustainable H2 production : To bring electrocatalytic hydrogen production into the sustainable realm, earth‐abundant metal catalysts should function with water as the substrate. These newly reported hydrogen‐generating catalysts of Ni II are robust, stable in air and electrocatalytically reduce water to hydrogen with excellent Faradaic efficiency. Computations supplemented our understanding of a unique ligand‐based electron transfer with the cooperativity of the PN 3 P ligand as an electron reservoir as a requirement for successful catalysis.