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Journal ArticleDOI: 10.1016/J.JALLCOM.2020.158219

Hetero-structured V-Ni3S2@NiOOH core-shell nanorods from an electrochemical anodization for water splitting

05 Mar 2021-Journal of Alloys and Compounds (Elsevier)-Vol. 856, pp 158219
Abstract: Developing cost-efficient bi-functional catalysts with high performance for electrochemical water splitting is of paramount significance but a challenge for the future energy scenario. Hetero-structure engineering has invoked new feasibilities to achieve comprehensive promotion for both activity and durability. However, there is still a grand challenge to develop a facile strategy for hetero-structure construction. Herein, V-Ni3S2 @NiOOH core-shell hetero-structure has been fabricated via a facile electrochemical anodization. It is demonstrated that this core-shell heterostructure featured with a thin but disordered NiOOH shell exhibits optimized structure and facilitated charge transfer resulting in a modulated catalytic activity as well as a structural stability. As expected, it is observed that the overpotential of V-Ni3S2 @NiOOH for HER shows 45 mV lower than that of Pt/C catalysts at 250 mA cm−2. The OER activity of V-Ni3S2 @NiOOH is comparable with that of RuO2 as well. This superior performance for both HER and OER indicates the potential of V-Ni3S2 @NiOOH to be an alternative to noble-metal-based catalysts for electrochemical water splitting. Our findings in this work may put forward a fresh concept and strategy to construct hetero-structure for many other high-performance energy materials using in the next-generation energy conversion and storage devices.

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Topics: Water splitting (51%)
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7 results found


Journal ArticleDOI: 10.1016/J.IJHYDENE.2021.09.190
Rui Tong1, Miao Xu1, Haiming Huang1, Chengrui Wu1  +6 moreInstitutions (2)
Abstract: Studying cheap and efficient electrocatalysts is of great significance to promote the sluggish kinetics of oxygen evolution reaction (OER). Here, we adopted a simple two-step method to successfully prepare the 3D V–Ni3S2@CoFe-LDH core-shell electrocatalyst. The V–Ni3S2@CoFe-LDH/NF shows excellent OER performance with low overpotential (190 mV at 10 mA/cm2 and 240 mV at 50 mA/cm2), small Tafel slope (26.8 mV/dec) and good long-term durability. Excitingly, to reach the same current density, V–Ni3S2@CoFe-LDH/NF electrode even needs much smaller overpotential than RuO2. Furthermore, the outstanding OER activity of V–Ni3S2@CoFe-LDH/NF is ascribed to the following reasons: (1) V–Ni3S2 nanorod cores improve the conductivity and ensure the fast charge transfer; (2) CoFe-LDH nanosheets interconnected with each other provide more exposed active sites; (3) the unique 3D core-shell structures are favorable for electrolyte diffusion and gas releasing. Our work indicates that building 3D core-shell heterostructure will be a useful way to design good electrocatalysts.

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Topics: Overpotential (58%), Electrocatalyst (52%), Tafel equation (52%)

1 Citations



Open accessJournal ArticleDOI: 10.1016/J.IJHYDENE.2021.10.216
Rui Wang1, Yang Yang2, Zhipeng Sun1, Xia Lu2Institutions (2)
Abstract: Exploring cost-efficient electrocatalysts for oxygen evolution reaction (OER) is still a huge challenge in the electrochemical energy conversion technology. In this work, Gallium (Ga)-doped Ni3S2 nanosheet arrays grown on Ti3C2-MXene/nickel foam (Ga–Ni3S2/Ti3C2/NF) have been synthesized by a successive hydrothermal and sulfidization process. The Ga doping modulates the electronic structure of Ni3S2, so tuning the adsorption energies of oxygen intermediate (∗OOH). The Ga–Ni3S2/Ti3C2/NF delivers outstanding catalytic activities toward OER with an overpotential of 340 mV at 100 mA cm−2, and exhibits superior electrochemical durability. The excellent OER performance of Ga–Ni3S2/Ti3C2/NF can be ascribed to the 3D sheet arrays morphology and optimized electronic structure. Density functional theory (DFT) calculations also demonstrate that electronic disturbance attributed to Ga doping effectively improves the activity of Ni sites, leading to stronger binding strength of ∗OOH intermediate at Ni sites nearby Ga. This study provides insights into the fabrication of advanced electrocatalysts for application.

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Topics: Electrocatalyst (55%), Nanosheet (54%), Overpotential (52%) ... read more

Journal ArticleDOI: 10.1039/D1DT02530A
Xiaoqiang Du1, Guangyu Ma1, Yanhong Wang1, Xinghua Han1  +1 moreInstitutions (1)
Abstract: The design and synthesis of hybrid core–shell catalysts is of great significance for obtaining an excellent performance of hydrogen evolution reaction (HER). However, it remains a challenge to explore the exact active sites and research the catalytic mechanism for HER. Here, a series of Ni3S2@MOOH/NF (M = Fe, Ni, Cu, Mn and Co) hybrid structures is firstly in-site grown on Ni foam by the typical hydrothermal and electrodeposition methods. The Ni3S2@NiOOH/NF catalyst with a core–shell structure exhibits a relatively low overpotential of 79 mV for HER at a current density of 10 mA cm−2, which is one of the best catalytic activities reported so far. Moreover, it also shows good stability in the long-term durability test. Various spectral analysis and density functional theory calculations demonstrate that NiOOH is favorable for the adsorption of water molecules, and the S atom at the interface between Ni3S2 and NiOOH is favorable for the adsorption of H intermediates, which strongly accelerates the HER process in alkaline solution. This work provides a general strategy for the synthesis of electrocatalytic materials, which can be used for efficient electrocatalytic water splitting reactions.

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Topics: Overpotential (54%), Water splitting (54%), Catalysis (52%) ... read more

Journal ArticleDOI: 10.1016/J.JELECHEM.2021.115555
Tao Zhou1, Yang Qi Huang1, Asad Ali1, Pei Kang Shen1Institutions (1)
Abstract: The development of heterostructures is an effective way to improve the efficiency of water decomposition. More heterojunction with smaller size is an important strategy to improve the utilization efficiency of non-noble metal active substances and further improve catalytic activity. Herein, the stereotaxically-constructed graphene (SCG) was synthesized by cationic exchange resin and was used as the substrate to prepared Ni-MoO2@SCG nanoparticles heterojunction (Ni is surrounded by MoO2) for the first time by hydrothermal process and annealing method. In urea solution, porous SCG restricted the transition of nanoparticles to microspheres, inhibited the aggregation of active substances, and provided a large number of anchoring sites for nanoparticles. In the process of high-temperature hydrogen reduction, Ni atoms precipitate to form nano-particles and form unique heterojunction particles of about 20 nm with MoO2. The synergistic effect at the interface between Ni and MoO2 significantly enhances the catalytic activity of MoO2. The as-prepared Ni-MoO2@SCG sample exhibits overpotentials of 79.97 mV and 278 mV to reach a current density of 10 mA cm−2 for HER and OER in 1.0 M KOH, respectively. More importantly, it performs stable overall water splitting with a cell voltage of 1.548 V at a current density of 10 mA cm−2 as both cathode and anode. Anchoring nano heterojunction particles on the surface of porous Stereotaxically-constructed graphene provides a new direction for improving the catalytic performance of powder's electrocatalysis.

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Topics: Water splitting (54%), Heterojunction (54%), Graphene (53%) ... read more

References
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36 results found


Journal ArticleDOI: 10.1126/SCIENCE.1211934
Ram Subbaraman1, Dusan Tripkovic1, Dusan Strmcnik1, Kee-Chul Chang1  +4 moreInstitutions (1)
02 Dec 2011-Science
Abstract: Improving the sluggish kinetics for the electrochemical reduction of water to molecular hydrogen in alkaline environments is one key to reducing the high overpotentials and associated energy losses in water-alkali and chlor-alkali electrolyzers. We found that a controlled arrangement of nanometer-scale Ni(OH)(2) clusters on platinum electrode surfaces manifests a factor of 8 activity increase in catalyzing the hydrogen evolution reaction relative to state-of-the-art metal and metal-oxide catalysts. In a bifunctional effect, the edges of the Ni(OH)(2) clusters promoted the dissociation of water and the production of hydrogen intermediates that then adsorbed on the nearby Pt surfaces and recombined into molecular hydrogen. The generation of these hydrogen intermediates could be further enhanced via Li(+)-induced destabilization of the HO-H bond, resulting in a factor of 10 total increase in activity.

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Topics: Water splitting (60%), Hydrogen (58%), Electrolysis of water (55%) ... read more

1,606 Citations


Journal ArticleDOI: 10.1021/JA502128J
Min-Rui Gao1, Wenchao Sheng1, Zhongbin Zhuang1, Qianrong Fang1  +3 moreInstitutions (1)
Abstract: Electrochemical water splitting is a clean technology that can store the intermittent renewable wind and solar energy in H2 fuels. However, large-scale H2 production is greatly hindered by the sluggish oxygen evolution reaction (OER) kinetics at the anode of a water electrolyzer. Although many OER electrocatalysts have been developed to negotiate this difficult reaction, substantial progresses in the design of cheap, robust, and efficient catalysts are still required and have been considered a huge challenge. Herein, we report the simple synthesis and use of α-Ni(OH)2 nanocrystals as a remarkably active and stable OER catalyst in alkaline media. We found the highly nanostructured α-Ni(OH)2 catalyst afforded a current density of 10 mA cm(-2) at a small overpotential of a mere 0.331 V and a small Tafel slope of ~42 mV/decade, comparing favorably with the state-of-the-art RuO2 catalyst. This α-Ni(OH)2 catalyst also presents outstanding durability under harsh OER cycling conditions, and its stability is much better than that of RuO2. Additionally, by comparing the performance of α-Ni(OH)2 with two kinds of β-Ni(OH)2, all synthesized in the same system, we experimentally demonstrate that α-Ni(OH)2 effects more efficient OER catalysis. These results suggest the possibility for the development of effective and robust OER electrocatalysts by using cheap and easily prepared α-Ni(OH)2 to replace the expensive commercial catalysts such as RuO2 or IrO2.

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Topics: Electrocatalyst (53%), Overpotential (52%), Water splitting (50%)

952 Citations



Journal ArticleDOI: 10.1002/AENM.201701592
Xin-Yao Yu1, Xiong Wen David Lou2Institutions (2)
Abstract: Mixed metal sulfides (MMSs) have attracted increased attention as promising electrode materials for electrochemical energy storage and conversion systems including lithium-ion batteries (LIBs), sodium-ion batteries (SIBs), hybrid supercapacitors (HSCs), metal–air batteries (MABs), and water splitting. Compared with monometal sulfides, MMSs exhibit greatly enhanced electrochemical performance, which is largely originated from their higher electronic conductivity and richer redox reactions. In this review, recent progresses in the rational design and synthesis of diverse MMS-based micro/nanostructures with controlled morphologies, sizes, and compositions for LIBs, SIBs, HSCs, MABs, and water splitting are summarized. In particular, nanostructuring, synthesis of nanocomposites with carbonaceous materials and fabrication of 3D MMS-based electrodes are demonstrated to be three effective approaches for improving the electrochemical performance of MMS-based electrode materials. Furthermore, some potential challenges as well as prospects are discussed to further advance the development of MMS-based electrode materials for next-generation electrochemical energy storage and conversion systems.

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460 Citations