Jana Debu, Alamgir Mohammed, Das Samar K
School of Chemistry, University of Hyderabad, P.O. Central University, Hyderabad 500046, India.
Inorg Chem. 2024 Jul 29;63(30):13959-13971. doi: 10.1021/acs.inorgchem.4c01296. Epub 2024 Jul 12.
In this work, we have described a polyoxometalate (POM)-based inexpensive and easily synthesizable compound [Co(HO)][{K(HO)}VO]·2HO (), which exhibits electrocatalytic hydrogen evolution in its aqueous solution without its decomposition (or electrodeposition), acting as a rare homogeneous electrocatalyst. Even though the compound [Co(HO)][{K(HO)}VO]·2HO () (soluble in water) shows electrocatalytic hydrogen evolution reaction (HER) activity because of the Coulombic attraction, including H-bonding interactions, between the [Co(HO)] cationic species and [{K(HO)}VO]anionic species, the individual homogeneous solutions of [VO] (source: Na[VO]·18HO) and [Co(HO)] (source: CoCl·6HO) do not show any electrocatalytic HER activity. We have thus established that the synergy of [VO] with [Co(HO)] in crystal matrix as well as in the aqueous solution of makes the compound a stable and highly active electrocatalyst for homogeneous HER in an aqueous solution. In order to corroborate these homogeneous HER studies, we performed density functional theory (DFT) calculations to show that decavanadate cluster anion [VO] interacts with hexa-aqua complex cation [Co(HO)] via strong H-bonding interactions, leading to a synergy effect that enables the cobalt center of [Co(HO)] to be an active site of HER in the present work.
在这项工作中，我们描述了一种基于多金属氧酸盐（POM）的廉价且易于合成的化合物[Co(H₂O)₆][{K(H₂O)}VO₄]·2H₂O（），它在其水溶液中表现出电催化析氢作用且不会分解（或电沉积），是一种罕见的均相电催化剂。尽管化合物[Co(H₂O)₆][{K(H₂O)}VO₄]·2H₂O（可溶于水）由于[Co(H₂O)₆]阳离子物种与[{K(H₂O)}VO₄]阴离子物种之间的库仑吸引力（包括氢键相互作用）而表现出电催化析氢反应（HER）活性，但[VO₄³⁻]（来源：Na₃VO₄·18H₂O）和[Co(H₂O)₆]²⁺（来源：CoCl₂·6H₂O）的单独均相溶液并未表现出任何电催化HER活性。因此我们确定，[VO₄³⁻]与[Co(H₂O)₆]²⁺在晶体基质以及的水溶液中的协同作用使得该化合物成为水溶液中均相HER的稳定且高活性电催化剂。为了证实这些均相HER研究，我们进行了密度泛函理论（DFT）计算，结果表明十钒酸盐簇阴离子[VO₄³⁻]通过强氢键相互作用与六水合络合阳离子[Co(H₂O)₆]²⁺相互作用，产生协同效应，使得[Co(H₂O)₆]²⁺的钴中心在本工作中成为HER的活性位点。
