The<i>in situ</i>formation of defective CoOOH catalysts from semi-oxidized Co for alkaline oxygen evolution reaction

Wang, Lan; Pan, Ya; Wu, Dan; Liu, Xiaokang; Cao, Linlin; Zhang, Wei; Chen, Honglei; Liu, Tong; Liu, Dong; Zhu, Wenkun; Ding, Tao; Wang, Yi; Ding, Chenglong; Kang, Caitao; Li, Changli; He, Jingfu; Yao, Takeshi

doi:10.1039/d2ta02989h

Cited by 17 publications

(13 citation statements)

References 49 publications

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“…To verify this hypothesis, we synthesized an analogous material by replacing NiO x (OH) 2– x (bulk) with CoOOH, constituting a two-layer structure with surface NiO x (OH) 2– x and bulk CoOOH (Figure a). Since the bulk redox transition from Co(OH) 2 to the conductive CoOOH occurred at ∼1.11 V vs RHE, much earlier than the ∼1.34 V vs RHE for bulk Ni redox transition, the oxidation kinetics could no longer be restricted by the Ni redox (Figure d) . The material exhibited a nanoplate morphology stacked on the carbon fiber paper substrate (Figure b).…”

Section: Resultsmentioning

confidence: 99%

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Origin of the Universal Potential-Dependent Organic Oxidation on Nickel Oxyhydroxide

Hao

Cao

et al. 2023

ACS Catal.

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The paired electrolysis via anodic organic oxidation and cathodic hydrogen evolution has been an emerging hydrogen production technology with high efficiency and high values. Nickel oxyhydroxide is a special electrocatalyst that is capable of selectively oxidizing various alcohols, aldehydes, and amines to the corresponding carboxylates and nitriles at more favorable potentials compared to the oxygen evolution reaction. However, its detailed molecular-level mechanism is still in debate, especially for the potential-dependent behavior of some organic substrates. In this study, we revealed that the nickel oxyhydroxide can be dissected into two functional regions with a more facilely oxidized surface for facilitated substrate adsorption and a relatively inert bulk phase for accelerated electron transfer via probe-assisted kinetics and in situ surface-enhanced Raman spectroscopy. The prerequisite of the two regions conceals a universal potential-dependent oxidation behavior for almost all organic substrates. Further combining with the computational investigation unravels the origin of this potential dependence from the exothermic O/N-centered adsorption process on the surface and the rate-limiting proton-coupled electron-transfer (PCET) steps for the C−H bond breaking that demands bulk electron conductivity. This provides a rationale for designing more conductive underlayers to break the intrinsic limitations of nickel oxyhydroxide toward more efficient organic electrooxidation processes.

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Section: Resultsmentioning

confidence: 99%

“…Since the bulk redox transition from 6d). 31 The material exhibited a nanoplate morphology stacked on the carbon fiber paper substrate (Figure 6b). S1).…”

Section: ■ Introductionmentioning

confidence: 99%

Origin of the Universal Potential-Dependent Organic Oxidation on Nickel Oxyhydroxide

Hao

Cao

et al. 2023

ACS Catal.

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“…The well oxidation and reduction were occurred in SCSCO6 compared to other catalysts (SCSCO4 and SCSCO8) and NF. The presence of active species of SCSCO6 at higher and lower oxidation states afforded more efficient activity of OER and HER [36,82,83] …”

Section: Resultsmentioning

confidence: 99%

“…The presence of active species of SCSCO6 at higher and lower oxidation states afforded more efficient activity of OER and HER. [36,82,83] To analyse the charge-transfer potential of SCSCO in OER and HER processes, the electrochemical impedance spectra was recorded (Figure 11b). In order to calculate the charge-transfer resistance (R ct ) of electrocatalyst in 1 M KOH, the randles equivalent circuit was used (Figure 11b inset: C dl -double-layer capacitance, R ct -charge-transfer resistance and, R s -electrolyte resistance).…”

Section: Electrochemical Activitymentioning

confidence: 99%

Solution combusted ultrathin Co₃O₄/CoO heterophase electrocatalyst for solar‐energy driven bifunctional water electrolysis

2023

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Potential low‐cost solution combustion synthesis of cobalt oxide (SCSCO: Co3O4/CoO) by using sugar as a fuel for H2 and O2 generation. Co3O4/CoO heterophase provided multiple functional sites and abundant interfaces between the components owing to synergistic effect. The sufficient adsorption sites in SCSCO6 favoured the formation of reactive intermediates which leads to extraordinary OER and HER process. The SCSCO6 exhibits η of 271 mV (102 mV dec−1) for OER and 174 mV (73 mV dec−1) for HER to achieve 10 mA cm−2 (without iR correction). TOF of SCSCO6 (OER: 0.0624 s−1/IrO2‐ 0.0185 s−1; HER: 0.0282 s−1/Pt ‐ 0.0843 s−1) was found to be higher than IrO2 and near to Pt, respectively. The SCSCO6 displays durability of 130 h with potential loss of 3.2 % (OER) and 3.0 % (HER). The disordered oxidation states and high surface area of SCSCO6 (BET ‐ 99 m2 g−1: ECSA ‐ 151.27 m2/g) facilitates the bifunctional activity. The fabricated water electrolyzer consist of SCSCO6//SCSCO6 affords 10 mA cm−2 @1.64 V and exhibits high stability (>130 h: 4.1 % potential loss). The solar‐to‐hydrogen electrolyser (SCSCO6//SCSCO6) afforded non‐stop evolution of H2 and O2 @1.63 V which can be recommended for low‐cost, large‐scale hydrogen production.

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“…Thus, a high voltage is required to drive the current density of the CO 2 RR system to meet the commercialization demand. 58–63 To this end, it is necessary to seek an alternative anodic reaction that can replace OER and can be coupled with CO 2 RR to achieve considerable improvement in terms of energy consumption and commercial value.…”

Section: Introductionmentioning

confidence: 99%

The design of alternative anodic reactions paired with electrochemical CO₂ reduction

et al. 2023

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Thein situformation of defective CoOOH catalysts from semi-oxidized Co for alkaline oxygen evolution reaction

Abstract: Semi-oxidized Co pre-catalysts are oxidized and self-assembled into defective CoOOH with a much higher O vacancy density during the OER, benefiting the bonding of oxygen species on the catalyst surface and promoting the catalytic activity.

Cited by 17 publications

References 49 publications

Origin of the Universal Potential-Dependent Organic Oxidation on Nickel Oxyhydroxide

Origin of the Universal Potential-Dependent Organic Oxidation on Nickel Oxyhydroxide

Solution combusted ultrathin Co₃O₄/CoO heterophase electrocatalyst for solar‐energy driven bifunctional water electrolysis

The design of alternative anodic reactions paired with electrochemical CO₂ reduction

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Thein situformation of defective CoOOH catalysts from semi-oxidized Co for alkaline oxygen evolution reaction

Abstract: Semi-oxidized Co pre-catalysts are oxidized and self-assembled into defective CoOOH with a much higher O vacancy density during the OER, benefiting the bonding of oxygen species on the catalyst surface and promoting the catalytic activity.

Cited by 17 publications

References 49 publications

Origin of the Universal Potential-Dependent Organic Oxidation on Nickel Oxyhydroxide

Origin of the Universal Potential-Dependent Organic Oxidation on Nickel Oxyhydroxide

Solution combusted ultrathin Co3O4/CoO heterophase electrocatalyst for solar‐energy driven bifunctional water electrolysis

The design of alternative anodic reactions paired with electrochemical CO2 reduction

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Product

Resources

About

Solution combusted ultrathin Co₃O₄/CoO heterophase electrocatalyst for solar‐energy driven bifunctional water electrolysis

The design of alternative anodic reactions paired with electrochemical CO₂ reduction