Hierarchical NiCoP nanocone arrays supported on Ni foam as an efficient and stable bifunctional electrocatalyst for overall water splitting

Li, Junzhi; Wei, Guodong; Zhu, Yukun; Xi, Yunlong; Pan, Xuexue; Ji, Yuan; Zatovsky, Іgor V.; Han, Wei

doi:10.1039/c7ta03947f

Cited by 278 publications

(115 citation statements)

References 72 publications

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“…The XRD pattern of flower‐like NiCoP/NF is shown in Figure (b) (top) together with that of plate‐like NiCoP/NF (bottom), in which diffraction peaks at 2θ=41.0°, 47.6° and 54.4° are observed in both XRD patterns and assigned to (111), (210) and (300) planes of hexagonal phase of NiCoP (JCPDS No.71‐2336), respectively. As such, it is proved that the new hydrothermal method without additional alkali sources can successfully fabricate similar NiCoP/NF catalyst to that by previously reported methods . Specifically, the intensities of diffraction peaks of flower‐like NiCoP/NF (top) are obviously stronger than the corresponding ones of plate‐like NiCoP/NF (bottom) while the same intensities of Ni diffraction peaks exist in the two XRD patterns.…”

Section: Resultssupporting

confidence: 54%

“…Figure (d) presents the narrow scanning XPS spectrum of P 2p, where two main peaks at 129.5 eV and 134.3 eV are observed. The peak at 129.5 eV is assigned to reduced P (P δ− ) in the metal phosphides, which has a lower binding energy than 130.0 eV of P element, a value reported by Li et al . This means that P element carried partial negative charges (δ − ) in flower‐like NiCoP/NF.…”

Section: Resultsmentioning

confidence: 79%

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A Self‐Assembled Flower‐Like Structure of Nickel‐Cobalt Phosphide Nanosheets Supported on Nickel Foam for Electrochemical Hydrogen Evolution Reaction

Zou

et al. 2019

ChemistrySelect

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In this study, flower‐like nickel‐cobalt phosphide (NiCoP) on Ni foam (flower‐like NiCoP/NF) was fabricated via a two‐step process, including hydrothermal and phosphorization. Hydrogen evolution reaction (HER) measurements show that such flower‐like NiCoP/NF is a highly efficient and stable electrocatalyst, which can keep high activity for more than 20 h at ambient temperature. Scanning electron microscope (SEM) images show that flower‐like NiCoP/NF uniformly covered the Ni foam surface. In the hydrothermal step, X‐ray photoelectron spectroscopy (XPS) results show that partial Co2+ ions from Co(NO3)2⋅6H2O were oxidized to Co3+ ions in the ethanol‐water solution. Meanwhile, NO3− ions from Ni(NO3)2⋅6H2O and Co(NO3)2⋅6H2O triggered the ethanol‐water solution to release OH− ions, which subsequently reacted with Ni2+, Co2+ and Co3+ ions to generate NiCo‐OH precipitation. Subsequently, in the phosphorization step NiCo‐OH was converted to NiCoP nanosheets by NaH2PO2 at a low temperature of 350 °C. The two‐step method employed in the present work avoids an addition of alkali sources or precipitators to the hydrothermal reaction solution, which is favorable for environmental protection strategies and sustainable development principles.

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Section: Resultssupporting

confidence: 54%

Section: Resultsmentioning

confidence: 79%

A Self‐Assembled Flower‐Like Structure of Nickel‐Cobalt Phosphide Nanosheets Supported on Nickel Foam for Electrochemical Hydrogen Evolution Reaction

Zou

et al. 2019

ChemistrySelect

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“…As shown in Figure E, the CoP‐Co 2 P@PC/PG NHs have the smallest Tafel slope (66 mV dec −1 ), and thereby their OER rate can increase quickly with the increase of potential. It should be mentioned that the OER activity of CoP‐Co 2 P@PC/PG NHs is also superior to CoP‐Co 2 P@PC NHs (Figure S19, Supporting Information), and most of recently reported OER catalysts, such as NiCoP‐NWAs/NF, Co 4 N/CNW/CC, Ni 3 (S 0.25 Se 0.75 ) 2 @NiOOH, and so on. The detailed comparison is given in Table S2 (Supporting Information).…”

Section: Resultsmentioning

confidence: 97%

Cobalt Phosphides Nanocrystals Encapsulated by P‐Doped Carbon and Married with P‐Doped Graphene for Overall Water Splitting

Yang

Guo

Zhao

et al. 2019

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As one class of important functional materials, transition metal phosphides (TMPs) nanostructures show promising applications in catalysis and energy storage fields. Although great progress has been achieved, phase‐controlled synthesis of cobalt phosphides nanocrystals or related nanohybrids remains a challenge, and their use in overall water splitting (OWS) is not systematically studied. Herein, three kinds of cobalt phosphides nanocrystals encapsulated by P‐doped carbon (PC) and married with P‐doped graphene (PG) nanohybrids, including CoP@PC/PG, CoP‐Co2P@PC/PG, and Co2P@PC/PG, are obtained through controllable thermal conversion of presynthesized supramolecular gels that contain cobalt salt, phytic acid, and graphene oxides at proper temperature under Ar/H2 atmosphere. Among them, the mixed‐phase CoP‐Co2P@PC/PG nanohybrids manifest high electrocatalytic activity toward both hydrogen and oxygen evolution in alkaline media. Remarkably, using them as bifunctional catalysts, the fabricated CoP‐Co2P@PC/PG||CoP‐Co2P@PC/PG electrolyzer only needs a cell voltage of 1.567 V for driving OWS to reach the current density at 10 mA cm−2, superior to their pure‐phase counterparts and recently reported bifunctional catalysts based devices. Also, such a CoP‐Co2P@PC/PG||CoP‐Co2P@PC/PG device exhibits outstanding stability for OWS. This work may shed some light on optimizing TMPs nanostructures based on phase engineering, and promote their applications in OWS or other renewable energy options.

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“…Highly efficient water electrolysis generally requires high-performance electrocatalysts with low overpotential, fast kinetics, and high stability. [9][10][11] Recently, transition-metal hydroxides, [7,12] phosphides, [8,[13][14][15][16] nitrides, [17,18] and chalcogenides [19][20][21][22] have been investigated as promising candidates for bifunctional electrocatalysts. [7,8] The search for earth-abundant, lowcost HER and OER electrocatalysts that are robust, have high activity and stability has triggered numerous efforts to replace noble metal-based materials.…”

Section: Introductionmentioning

confidence: 99%

3D Architectures of Quaternary Co‐Ni‐S‐P/Graphene Hybrids as Highly Active and Stable Bifunctional Electrocatalysts for Overall Water Splitting

Song

Yoon

et al. 2018

Advanced Energy Materials

113

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Developing low-cost, highly active, and stable bifunctional electrocatalysts is a challenging issue in electrochemical water electrolysis. Building on 3D architectured electrocatalysts through structural and compositional engineering is an effective strategy to enhance catalytic activities as well as stability and durability. Herein, 3D architectures of quaternary Co-Ni-S-P compounds coupled with graphene ((Co 1−x Ni x )(S 1−y P y ) 2 /G) electrocatalysts are proposed, in which nanosheets are self-assembled to form 3D architectures with round and flat doughnut-like shapes, toward overall water splitting. Benefiting from the 3D architectures and Ni, P substitution, (Co 1−x Ni x )(S 1−y P y ) 2 /G exhibits superior electrocatalytic activities with low overpotentials of 117 and 285 mV at 10 mA cm −2 and Tafel slopes of 85 and 105 mV dec −1 for hydrogen and oxygen evolution reactions, respectively, in alkaline media. In addition, minimal increases in overpotential are observed, even after the 10 000th voltammetric cycle and continuous chronopotentiometric testing over 50-100 h, confirming the high stability and durability of (Co 1−x Ni x )(S 1−y P y ) 2 /G. When used as both cathode and anode, (Co 1−x Ni x )(S 1−y P y ) 2 /G achieves excellent overall water splitting performance with a cell potential as low as 1.65 V, reaching a current density of 10 mA cm −2 with no obvious decay after 50 h, demonstrating that (Co 1−x Ni x )(S 1−y P y ) 2 /G is an efficient bifunctional electrocatalyst for overall water splitting.

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Hierarchical NiCoP nanocone arrays supported on Ni foam as an efficient and stable bifunctional electrocatalyst for overall water splitting

Abstract: NiCoP cone-shaped nanowire arrays as an efficient and stable bifunctional electrocatalyst for overall water splitting.

Cited by 278 publications

References 72 publications

A Self‐Assembled Flower‐Like Structure of Nickel‐Cobalt Phosphide Nanosheets Supported on Nickel Foam for Electrochemical Hydrogen Evolution Reaction

A Self‐Assembled Flower‐Like Structure of Nickel‐Cobalt Phosphide Nanosheets Supported on Nickel Foam for Electrochemical Hydrogen Evolution Reaction

Cobalt Phosphides Nanocrystals Encapsulated by P‐Doped Carbon and Married with P‐Doped Graphene for Overall Water Splitting

3D Architectures of Quaternary Co‐Ni‐S‐P/Graphene Hybrids as Highly Active and Stable Bifunctional Electrocatalysts for Overall Water Splitting

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