Electrocatalytic Hydrogen Evolution using a Nickel-based Calixpyrrole Complex: Controlling the Secondary Coordination Sphere on an Electrode Surface.

Autor: Trowbridge L; Department of Chemistry, Kansas State University, 1212 Mid-Campus Drive North, Manhattan, Kansas, 66503, USA., Averkiev B; Department of Chemistry, Kansas State University, 1212 Mid-Campus Drive North, Manhattan, Kansas, 66503, USA., Sues PE; Department of Chemistry, Kansas State University, 1212 Mid-Campus Drive North, Manhattan, Kansas, 66503, USA.
Jazyk: angličtina
Zdroj: Chemistry (Weinheim an der Bergstrasse, Germany) [Chemistry] 2023 Nov 21; Vol. 29 (65), pp. e202301920. Date of Electronic Publication: 2023 Oct 13.
DOI: 10.1002/chem.202301920
Abstrakt: Incorporating design elements from homogeneous catalysts to construct well defined active sites on electrode surfaces is a promising approach for developing next generation electrocatalysts for energy conversion reactions. Furthermore, if functionalities that control the electrode microenvironment could be integrated into these active sites it would be particularly appealing. In this context, a square planar nickel calixpyrrole complex, Ni(DPMDA) (DPMDA=2,2'-((diphenylmethylene)bis(1H-pyrrole-5,2-diyl))bis(methaneylylidene))bis(azaneylylidene))dianiline) with pendant amine groups is reported that forms a heterogeneous hydrogen evolution catalyst using anilinium tetrafluoroborate as the proton source. The supported Ni(DPMDA) catalyst was surprisingly stable and displayed fast reaction kinetics with turnover frequencies (TOF) up to 25,900 s -1 or 366,000 s -1  cm -2 . Kinetic isotope effect (KIE) studies revealed a KIE of 5.7, and this data, combined with Tafel slope analysis, suggested that a proton-coupled electron transfer (PCET) process involving the pendant amine groups was rate-limiting. While evidence of an outer-sphere reduction of the Ni(DPMDA) catalyst was observed, it is hypothesized that the control over the secondary coordination sphere provided by the pendant amines facilitated such high TOFs and enabled the PCET mechanism. The results reported herein provide insight into heterogeneous catalyst design and approaches for controlling the secondary coordination sphere on electrode surfaces.
(© 2023 Wiley-VCH GmbH.)
Databáze: MEDLINE
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