Electrocatalytic Oxidation of Hydroxide Ions by Co₃O₄ and Co₃O₄@SiO₂ Nanoparticles Both at Particle Ensembles and at the Single Particle Level

Abstract

We report that the Co3O4 nanoparticle‐mediated electrochemical oxidation under alkaline conditions of the hydroxide ion on a glassy carbon macroelectrode leads to hydrogen peroxide as the initial oxidation product of electron transfer. The latter is inferred to subsequently partially decompose to dioxygen by catalytic chemical reaction at the nanoparticles. At the single particle level, electrochemical particle‐electrode impacts point out the rate‐determining step and the limiting kinetics of the reaction. Furthermore, particles with a core‐shell structure of a Co3O4 core and SiO2 shell are synthesised, and their electrochemical behaviour is studied and compared with bare Co3O4 nanoparticles, suggesting the very likely broken or highly porous state of the silica shell, which is not otherwise easily distinguished, for example, by electron microscopy.

Ultrasound-Engineered fabrication of immobilized molybdenum complex on Cross-Linked poly (Ionic Liquid) as a new acidic catalyst for the regioselective synthesis of pharmaceutical polysubstituted spiro compounds

“…The mentioned peaks that appeared were consistent with Co 3 O 4 (JCPDS No. 01–080-1533, fcc, Fd3m) [37] . A broad peak about 2Θ = 22° is attributed to the amorphous Si [38] .…”

Semiconducting Nanoparticles: Single Entity Electrochemistry and Photoelectrochemistry

“…In recent years, the electrochemical behavior of single MOS including IrO x , Fe 2 O 3 , Fe 3 O 4 , CeO 2 , CuO, Co 3 O 4 , TiO 2 , ZnO and CoFe 2 O 4 etc. has been investigated via nano-impact method ( Sardesai et al, 2013 ; Tschulik and Compton, 2014 ; Shimizu et al, 2016a ; Shimizu et al, 2016b ; Zhou et al, 2017 ; Zampardi, et al, 2018 ; Peng et al, 2018 ; Xie et al, 2020 ; Karunathilake et al, 2020 ) The specific research topics mainly involve two aspects: the electrochemical redox behavior and electrocatalysis of single MOS, which is summarized and discussed in the following paragraphs respectively. For a direct type of nano-impact, the nanoparticles are usually fully oxidized (or reduced) so that the electrolysis of the nanoparticles is quantitative.…”

“…Some significant applications of the mediated electron transfer for MOS have been reported, examples cover IrO x , Fe 2 O 3 , Co 3 O 4 and CoFe 2 O 4 NPs. ( Zhou et al, 2017 ; Kwon et al, 2010 ; Shimizu et al, 2016a , b ; Xie et al, 2020 ; El Arrassi et al, 2019 ). The initial studies on the mediated impacts of MOS reported the enhanced current transients from the electrocatalysis of individual impacting IrO x NPs toward oxygen evolution reaction (OER).…”

“…Recently Xie et al reported the water oxidation on single Co 3 O 4 nanoparticles, a mechanism involving hydrogen peroxide as the initial oxidation product of electron transfer and a following decomposition to form dioxygen was proposed. Single particle electrocatalysis points out the rate-determining step and the limiting kinetics of the reaction ( Xie et al, 2020 ). El Arrassi et al investigated the OER on single CoFe 2 O 4 NPs and revealed that the current density at single nanoparticle researches as high as several kA·m −2 .…”

Single-entity coccolithophore electrochemistry shows size is no guide to the degree of calcification

“…At the most basic level, characterising the behaviour of a single unit in any system, for example, in catalysis, cellular biology, enzyme or reaction kinetics, allows the ensemble response to be better understood and optimised. In the modern era, with advances in electronic components and with a large arsenal of redox systems at the user's disposal, electrochemistry has claimed notable successes in stochastic measurements 1 in the detection of, but not limited to, single nanoparticles, 2 electrocatalysis, 3,4 red blood cells, 5 bacteria 6,7 and viruses. 8 In the world's ocean, calcifying marine phytoplanktoncoccolithophoresplay a crucial role in the global carbon cycle 9 owing to their ability to sequester in excess of 10 15 g of CaCO 3 to the deep ocean per annum.…”