A polyoxometalate supported copper dimeric complex: Synthesis, structure and electrocatalysis

Kumar, Naresh; Bhoi, Umashis; Naulakha, Pragya; Das, Samar K.

doi:10.1016/j.ica.2020.119554

Cited by 7 publications

(3 citation statements)

References 74 publications

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“…Equations – demonstrate proton-coupled electrochemical reactions, leading to the formation of the [Cu IV O] 2+ group that can oxidize water chemically to form oxygen with the regeneration of Cu(II) species (eqs –). This electrocatalytic water oxidation description (eqs –) is also supported by various literature studies. − false[ Cu normalI ( H 2 O ) false] + − normale − → false[ Cu II ( H 2 O ) false] 2 + false[ Cu II ( H 2 O ) false] 2 + − normale − → false[ Cu III ( H 2 O ) false] 3 + false[ Cu III ( H 2 …”

Section: Resultssupporting

confidence: 82%

Section: Resultssupporting

confidence: 79%

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Hydroxylated Polyoxometalate with Cu(II)- and Cu(I)-Aqua Complexes: A Bifunctional Catalyst for Electrocatalytic Water Splitting at Neutral pH

2023

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A sole inorganic framework material [Li(H2O)4][{CuI(H2O)1.5} {CuII(H2O)3}2{WVI 12O36(OH)6}]·N2·H2S·3H2O (1) consisting of a hydroxylated polyoxometalate (POM) anion, {WVI 12O36(OH)6}6–, a mixed-valent Cu(II)– and Cu(I)–aqua cationic complex species, [{CuI(H2O)1.5}{CuII(H2O)3}2]5+, a Li(I)-aqua complex cation, and three solvent molecules, has been synthesized and structurally characterized. During its synthesis, the POM cluster anion gets functionalized with six hydroxyl groups, i.e., six WVI–OH groups per cluster unit. Moreover, structural and spectral analyses have shown the presence of H2S and N2 molecules in the concerned crystal lattice, formed from “sulfate-reducing ammonium oxidation (SRAO)”. Compound 1 functions as a bifunctional electrocatalyst exhibiting oxygen evolution reaction (OER) by water oxidation and hydrogen evolution reaction (HER) by water reduction at the neutral pH. We could identify that the hydroxylated POM anion and copper-aqua complex cations are the functional sites for HER and OER, respectively. The overpotential, required to achieve a current density of 1 mA/cm2 in the case of HER (water reduction), is found to be 443 mV with a Faradaic efficiency of 92% and a turnover frequency of 4.66 s–1. In the case of OER (water oxidation), the overpotential needed to achieve a current density of 1 mA/cm2 is obtained to be 418 mV with a Faradaic efficiency of 88% and turnover frequency of 2.81 s–1. Diverse electrochemical controlled experiments have been performed to conclude that the title POM-based material functions as a true bifunctional catalyst for electrocatalytic HER as well as OER at the neutral pH without catalyst reconstruction.

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Section: Resultssupporting

confidence: 82%

Section: Resultssupporting

confidence: 79%

Hydroxylated Polyoxometalate with Cu(II)- and Cu(I)-Aqua Complexes: A Bifunctional Catalyst for Electrocatalytic Water Splitting at Neutral pH

2023

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“…POM-based soft-oxometalates have been explored for various electrochemical catalytic processes such as electrochemical CO 2 reduction or water oxidation . Our group has initiated PSTMCs for their electrocatalytic activity in the OER/HER . Inspired by the recent report and motivated by its scarcity in the literature, we designed new POM-supported copper coordination complexes for the OER/HER.…”

Section: Introductionmentioning

confidence: 99%

Devising a Polyoxometalate-Based Functional Material as an Efficient Electrocatalyst for the Hydrogen Evolution Reaction

et al. 2021

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Hydrogen is the solution to all the problems associated with the energy crisis. Generating hydrogen from water splitting is one of the greener approaches, but it requires an efficient catalyst that is economical for the bulk production of hydrogen. The transition metal-aqua coordination complexes, which are otherwise inactive/unstable for electrochemical hydrogen evolution reaction (HER) activity, can efficiently be utilized for the same by attaching these metal-aqua species on a stable support. With a similar approach, we have synthesized and structurally characterized a two-dimensional polyoxometalate (POM)-copper complex hybrid that supports a copper(II)-aqua-bypyridine complex with a molecular formula of the overall system, [{Cu II . The bis(aqua)-mono(bipyridine) Cu(II)-complex fragment {Cu II (2,2′bpy)(H 2 O) 2 } 2+ , attached to the two-dimensional POM-Cu-complex support, acts as an active catalytic center that catalyzes the electrochemical HER. The electrochemical studies done for this work enabled us to understand the role of compound 1 as an electrocatalyst for the HER in near-neutral medium (pH 4.8), under buffered conditions (acetate buffer). Through detailed electrochemical experiments including controlled ones, we understand that compound 1 follows a proton-coupled electron transfer (PCET) pathway with one proton and one electron involvement in the HER. The overpotential required to achieve a current density of 1 mA/cm 2 is found to be 520 mV with a Faradaic efficiency of 81%.

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Hydration of Alkynes to Ketones with an Efficient and Practical Polyoxomolybdate‐based Cobalt Catalyst

Xie

Wang

et al. 2021

ChemCatChem

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Hydration of alkynes to ketones is one of the most atom economical and universal methods for the synthesis of carbonyl compounds. However, the basic reaction usually requires organic ligand catalysts or harsh reaction conditions to insert oxygen into the C�C bond. Here, we report an inorganic ligand supported cobalt (III) catalyst, (NH 4 ) 3 [CoMo 6 O 18 (OH) 6 ], which is supported by a central cobalt (III) mononucleus and a ringshaped pure inorganic ligand composed of six Mo VI O 6 octahe-drons to avoid the disadvantages of expensive and unrecyclable organic ligand catalysts or noble metal catalysts. Under mild conditions, the cobalt (III) catalyst can be used for the hydration of alkynes to ketones. The catalyst is non-toxic, green, and environment friendly. The catalyst can be recycled at least six times with high activity. According to control experiments, a reasonable mechanism is provided.

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A polyoxometalate supported copper dimeric complex: Synthesis, structure and electrocatalysis

Cited by 7 publications

References 74 publications

Hydroxylated Polyoxometalate with Cu(II)- and Cu(I)-Aqua Complexes: A Bifunctional Catalyst for Electrocatalytic Water Splitting at Neutral pH

Hydroxylated Polyoxometalate with Cu(II)- and Cu(I)-Aqua Complexes: A Bifunctional Catalyst for Electrocatalytic Water Splitting at Neutral pH

Devising a Polyoxometalate-Based Functional Material as an Efficient Electrocatalyst for the Hydrogen Evolution Reaction

Hydration of Alkynes to Ketones with an Efficient and Practical Polyoxomolybdate‐based Cobalt Catalyst

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