Edge Sites with Unsaturated Coordination on Core–Shell Mn3O4@MnxCo3−xO4 Nanostructures for Electrocatalytic Water Oxidation

Hu, Congling; Zhang, Lei; Zhao, Zhi‐Jian; Luo, Jun; Shi, Jing; Huang, Zhiqi; Gong, Jinlong

doi:10.1002/adma.201701820

Cited by 125 publications

(67 citation statements)

References 45 publications

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“…Recently, Gong and co-workers have devised an edge-site-enriched core-shell Mn 3 O 4 @Co x Mn 3−x O 4 oxides nanoparticles (Mn@CoMnO NPs) (inset in Figure 3a) through an ion exchange of Co ions with Mn ions on the surface of Mn 3 O 4 seed for OER. [95] They reveal that the existence of abundant edge sites has promoted the generation of oxygen vacancies in the hybrid particles, which results in the direct structural exposure of Co atoms with open coordination sites, as illustrated in Figure 3b. Such unsaturated coordination sites with missing oxygen atoms are proposed to be unstable in alkaline condition and are easily filled by OH − groups, which can reduce the overpotential for the H 2 O dissociation or favor the OH − conversion to a more active oxyhydroxide species.…”

Section: Anion Vacanciesmentioning

confidence: 96%

“…In addition to Co 3 O 4 , the oxygen‐vacancy‐induced electrocatalytic activity enhancement has also been observed in other transition‐metal oxides. Recently, Gong and co‐workers have devised an edge‐site‐enriched core–shell Mn 3 O 4 @Co x Mn 3− x O 4 oxides nanoparticles (Mn@CoMnO NPs) (inset in Figure a) through an ion exchange of Co ions with Mn ions on the surface of Mn 3 O 4 seed for OER . They reveal that the existence of abundant edge sites has promoted the generation of oxygen vacancies in the hybrid particles, which results in the direct structural exposure of Co atoms with open coordination sites, as illustrated in Figure b.…”

Section: Classification Of Functional Vacanciesmentioning

confidence: 99%

“…a) LSV curves of OER for Mn@CoMnO NPs, RuO 2 , and Ni foam in 1 m KOH (inset shows the structural model); b) structural illustration of the edge‐site‐enriched Mn@CoMnO NPs with unsaturated coordination. Reproduced with permission . Copyright 2017, John Wiley & Sons, Inc. c) LSV curves of HER for Pt foil, Pt/carbon cloth (Pt/CC), MoS 3.1 , and MoS 1.7 in 0.5 m H 2 SO 4 .…”

Section: Classification Of Functional Vacanciesmentioning

confidence: 99%

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Noble Metal‐Free Nanocatalysts with Vacancies for Electrochemical Water Splitting

Yang

Wang

et al. 2018

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The fast development of nanoscience and nanotechnology has significantly advanced the fabrication of nanocatalysts and the in-depth study of the structural-activity characteristics of materials at the atomic level. Vacancies, as typical atomic defects or imperfections that widely exist in solid materials, are demonstrated to effectively modulate the physicochemical, electronic, and catalytic properties of nanomaterials, which is a key concept and hot research topic in nanochemistry and nanocatalysis. The recent experimental and theoretical progresses achieved in the preparation and application of vacancy-rich nanocatalysts for electrochemical water splitting are explored. Engineering of vacancies has shown to open up a new avenue beyond the traditional morphology, size, and composition modifications for the development of nonprecious electrocatalysts toward efficient energy conversion. First, an introduction followed by discussions of different types of vacancies, the approaches to create vacancies, and the advanced techniques widely used to characterize these vacancies are presented. Importantly, the correlations between the vacancies and activities of the vacancy-rich electrocatalysts via tuning the electronic states, active sites, and kinetic energy barriers are reviewed. Finally, perspectives on the existing challenges along with some opportunities for the further development of vacancy-rich noble metal-free electrocatalysts with high performance are discussed.

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Section: Anion Vacanciesmentioning

confidence: 96%

Section: Classification Of Functional Vacanciesmentioning

confidence: 99%

Section: Classification Of Functional Vacanciesmentioning

confidence: 99%

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Noble Metal‐Free Nanocatalysts with Vacancies for Electrochemical Water Splitting

Yang

Wang

et al. 2018

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“…As electrocatalytic OER occurs preferentially on atoms that are exposed on surface to catalysts, greater number of highly active sites usually produces better catalytic activity. Moreover, atoms located at various coordination sites, crystal faces, edges, terraces, and corners usually exhibit distinct catalytic activity, which can thus be considered as a reasonable strategy to tailor OER performance for M 3 Ge 2 O 5 (OH) 4 materials. Similar to most naturally metal layered double hydroxides, M 3 Ge 2 O 5 (OH) 4 grows preferentially into nanosheet morphology .…”

Section: Introductionmentioning

confidence: 99%

Serpentine Ni₃Ge₂O₅(OH)₄ Nanosheets with Tailored Layers and Size for Efficient Oxygen Evolution Reactions

Zhang

Yang

et al. 2018

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Layered serpentine Ni3Ge2O5(OH)4 is compositionally active and structurally favorable for adsorption and diffusion of reactants in oxygen evolution reactions (OER). However, one of the major problems for these materials is limited active sites and low efficiency for OER. In this regard, a new catalyst consisting of layered serpentine Ni3Ge2O5(OH)4 nanosheets is introduced via a controlled one‐step synthetic process where the morphology, size, and layers are well tailored. The theoretical calculations indicate that decreased layers and increased exposure of (100) facets in serpentine Ni3Ge2O5(OH)4 lead to much lower Gibbs free energy in adsorption of reactive intermediates. Experimentally, it is found that the reduction in number of layers with minimized particle size exhibits plenty of highly surface‐active sites of (100) facets and demonstrates a much enhanced performance in OER than the corresponding multilayered nanosheets. Such a strategy of tailoring active sites of serpentine Ni3Ge2O5(OH)4 nanosheets offers an effective method to design highly efficient electrocatalysts.

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“…The heterojunction between the metallic core and the (oxy)hydroxide shell is of great benefit to charge transport and OER activity. [ 23,24 ] For example, the improved electron transfer could be attributed to the in situ‐formed interface metal/metal hydroxide heterojunction. [ 23 ] Coupling with electrically conductive materials (carbon nanotube, [ 25 ] graphene [ 26 ] ) seems to be another promising method.…”

Section: Introductionmentioning

confidence: 99%

Core–Shell Structured NiFeSn@NiFe (Oxy)Hydroxide Nanospheres from an Electrochemical Strategy for Electrocatalytic Oxygen Evolution Reaction

Chen

et al. 2020

Advanced Science

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fuels. [1][2][3][4][5] However, as a half reaction, oxygen evolution reaction (OER) involves multiple electron and proton transfer and is considered to be the bottleneck of the overall water splitting. [6] It is of vital importance to develop efficient OER catalysts to accelerate the sluggish reaction and reduce the energy consumption. [7][8][9] Unfortunately, although the noble metalbased catalysts (e.g., IrO 2 , RuO 2 ) have been recognized to be the state-of-the-art OER catalysts, their dearth and high cost greatly impede their scalable application and commercialization. Therefore, developing OER catalysts with low cost as well as high performance is still a great challenge.Earth-abundant transition metal (especially Fe, Co, Ni) oxides or hydroxides, which possess multiple oxidation states, are often regarded as alternatives to precious metal-based catalysts towards OER. [10,11] Among them, NiFe (oxy) hydroxide has been proven to be one of the most effective materials under alkaline conditions. It is worth noting that transition metal oxides or hydroxides are semiconductors with poor intrinsic conductivity, which greatly obstruct their catalytic performance. [12] Thus, different strategies are developed to enhance electron transfer. One common approach is to fabricate metallic precursors (metals, [13] alloys, [14,15] phosphides, [16][17][18] nitrides, [19][20][21] borides [22] ) as precatalysts. The surface would be oxidized to oxide or hydroxide as the real active sites, which is evidenced by the experimental observations after the process of OER. The heterojunction between the metallic core and the (oxy)hydroxide shell is of great benefit to charge transport and OER activity. [23,24] For example, the improved electron transfer could be attributed to the in situformed interface metal/metal hydroxide heterojunction. [23] Coupling with electrically conductive materials (carbon nanotube, [25] graphene [26] ) seems to be another promising method. There are also some studies that investigate how the vacancies increase the conductivity of the electrocatalysts. [27,28] According to density functional theory calculations, introducing oxygen vacancies led to easy excitation of delocalized electron to conduction band, and hence the conductivity was enhanced. [28] On the other hand, the electrocatalytic OER process occurs at the electrode/electrolyte interface, which means that higher value of electrochemical active surface area (ECSA) Efficient electrocatalysts for the oxygen evolution reaction (OER) are highly desirable because of the intrinsically sluggish kinetics of OER. Herein, coreshell structured nanospheres of NiFe x Sn@NiFe (oxy)hydroxide (denoted as NiFe x Sn-A) are prepared as active OER catalysts by a facile electrochemical strategy, which includes electrodeposition of NiFe x Sn alloy nanospheres on carbon cloth (CC) and following anodization. The alloy core of NiFe x Sn could promote charge transfer, and the amorphous shell of NiFe (oxy)hydroxide is defect-rich and nanoporous due to the selective electroch...

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Edge Sites with Unsaturated Coordination on Core–Shell Mn₃O₄@Mn_xCo₃₋_xO₄ Nanostructures for Electrocatalytic Water Oxidation

Cited by 125 publications

References 45 publications

Noble Metal‐Free Nanocatalysts with Vacancies for Electrochemical Water Splitting

Noble Metal‐Free Nanocatalysts with Vacancies for Electrochemical Water Splitting

Serpentine Ni₃Ge₂O₅(OH)₄ Nanosheets with Tailored Layers and Size for Efficient Oxygen Evolution Reactions

Core–Shell Structured NiFeSn@NiFe (Oxy)Hydroxide Nanospheres from an Electrochemical Strategy for Electrocatalytic Oxygen Evolution Reaction

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Edge Sites with Unsaturated Coordination on Core–Shell Mn3O4@MnxCo3−xO4 Nanostructures for Electrocatalytic Water Oxidation

Cited by 125 publications

References 45 publications

Noble Metal‐Free Nanocatalysts with Vacancies for Electrochemical Water Splitting

Noble Metal‐Free Nanocatalysts with Vacancies for Electrochemical Water Splitting

Serpentine Ni3Ge2O5(OH)4 Nanosheets with Tailored Layers and Size for Efficient Oxygen Evolution Reactions

Core–Shell Structured NiFeSn@NiFe (Oxy)Hydroxide Nanospheres from an Electrochemical Strategy for Electrocatalytic Oxygen Evolution Reaction

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Edge Sites with Unsaturated Coordination on Core–Shell Mn₃O₄@Mn_xCo₃₋_xO₄ Nanostructures for Electrocatalytic Water Oxidation

Serpentine Ni₃Ge₂O₅(OH)₄ Nanosheets with Tailored Layers and Size for Efficient Oxygen Evolution Reactions