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Journal ArticleDOI: 10.1039/D0TA10281D

MoC nanodots toward efficient electrocatalytic hydrogen evolution: an interlayer-confined strategy with a 2D-zeolite precursor

02 Mar 2021-Journal of Materials Chemistry (The Royal Society of Chemistry)-Vol. 9, Iss: 8, pp 4724-4733
Abstract: An efficient electrocatalyst of molybdenum carbide nanodots on carbon nanosheets (nano-MoC/C-Ns) is prepared via a novel interlayer-confined strategy with the aid of MCM-22(P), a kind of multilayered two-dimensional (2D) zeolite precursor. In this strategy, the confined space of the surfactant-swollen MCM-22(P) plays a critical role in creating a unique sandwich-like structure with Mo-based organic–inorganic nanohybrids which further in situ evolve into ultrafine ∼2 nm MoC nanodots on carbon nanosheets in the following carbonization process. After etching the zeolite layers, the nano-MoC/C-Ns is successfully obtained as an efficient noble-metal-free electrocatalyst for hydrogen evolution. The intimate contact between ultrafine MoC nanodots and C nanosheets, as well as their synergetic effects, endows this catalyst with large exposed active sites and accelerated electron transport. The optimal sample achieves excellent hydrogen evolution reaction performance in acidic, neutral and alkaline media with low η10 values of 126, 185 and 92 mV (vs. the values of 28, 36 and 37 mV for a Pt/C reference in acidic, neutral and alkaline media), respectively. This synthetic strategy provides some hints for designing high-performance carbides for energy conversion and storage.

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Topics: Electrocatalyst (56%), Nanodot (54%)
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5 results found


Journal ArticleDOI: 10.1039/D1DT01809D
Tiantian Zhang1, Jianfei Yu1, Jiyao Huang1, Shengnan Lan1  +2 moreInstitutions (1)
Abstract: Metal halide perovskites, such as iodine methylamine lead (MAPbI3), have received extensive attention in the field of photocatalytic decomposition of HI for hydrogen evolution, due to their excellent photoelectric properties. In this paper, a new MAPbI3-based composite, MoC/MAPbI3, was synthesized. The results show that 15 wt% MoC/MAPbI3 has the best hydrogen production performance (38.4 μmol h−1), which is approximately 24-times that of pure MAPbI3 (1.61 μmol h−1). With the extension of the catalytic time, the hydrogen production rate of MoC/MAPbI3 reached 165.3 μmol h−1 after 16 h due to the effective separation and transfer of charge carriers between MoC and MAPbI3, showing excellent hydrogen evolution rate performance under visible light. In addition, the cycling stability of MoC/MAPbI3 did not decrease in multiple 4 h cycle tests. This study used the non-precious metal promoter MoC to modify MAPbI3, and provides a new idea for the synthesis of efficient MAPbI3-based composite catalysts.

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Topics: Hydrogen production (53%)

1 Citations


Journal ArticleDOI: 10.1021/ACS.INORGCHEM.1C02639
Manman Guo1, Fen Qiu1, Yuxi Yuan1, Ting Yu1  +2 moreInstitutions (1)
Abstract: As the core of an electrocatalyst, the active site is critical to determine its catalytic performance in the hydrogen evolution reaction (HER). In this work, porous N-doped carbon-encapsulated CoP nanoparticles on both sides of graphene (CoP@NC/GR) are derived from a bimetallic metal-organic framework (MOF)@graphene oxide composite. Through active site engineering by tailoring the environment around CoP and engineering the structure, the HER activity of CoP@NC/GR heterostructures is significantly enhanced. Both X-ray photoelectron spectroscopy (XPS) results and density functional theory (DFT) calculations manifest that the electronic structure of CoP can be modulated by the carbon matrix of NC/GR, resulting in electron redistribution and a reduction in the adsorption energy of hydrogen (ΔGH*) from -0.53 to 0.04 eV. By engineering the sandwich-like structure, active sites in CoP@NC/GR are further increased by optimizing the Zn/Co ratio in the bimetallic MOF. Benefiting from this active site engineering, the CoP@NC/GR electrocatalyst exhibits small overpotentials of 105 mV in 0.5 M H2SO4 (or 125 mV in 1 M KOH) to 10 mA cm-2, accelerated HER kinetics with a low Tafel slope of 47.5 mV dec-1, and remarkable structural and HER stability.

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Topics: Electrocatalyst (55%), Graphene (50%)

Journal ArticleDOI: 10.1039/D1TA03164C
Yanlong Lv1, Jian Ru Gong1Institutions (1)
Abstract: The design of a universal synthetic strategy for long-term durable transition metal carbide catalysts with a controllable nanostructure and sufficient active sites for the hydrogen evolution reaction is challenging. Herein, the in situ growth of Mo-containing MOFs was achieved on three-dimensional (3D) nickel foam (NF) through the conversion of pre-deposited bimetal hydroxide/oxide nanosheets (Mo and Co). After pyrolysis, ultrafine Mo carbide nanoparticles encapsulated in cobalt and nitrogen-doped carbon layers were obtained. The ultrafine metal carbide nanoparticles favored the exposure of active sites, the in situ growth enhanced the binding between catalysts and substrate, and the cobalt and nitrogen-doped carbon layer facilitated charge transfer. The MoxC electrode showed a current of 10 mA cm−2 at an overpotential of 33.5 mV under alkaline conditions, which was 6 mV lower than that of the 20% Pt/C/NF electrode. The WxC electrode was also prepared. This work highlights a novel universal strategy to synthesize metal carbide electrodes.

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Topics: Carbide (63%), Cobalt (55%), Overpotential (54%) ... show more

Journal ArticleDOI: 10.1007/S10854-021-06906-2
Weili Wang1, Guoxun Sun1, Xiaoning Sun1, Meng Huang1  +2 moreInstitutions (1)
Abstract: Carbides are typical electromagnetic microwave (EM) absorbing materials, due to their excellent dielectric properties. Large-scale synthesis of carbides through simple and low-cost methods is a necessary demand for EM pollution treatment. In this work, molybdenum carbide (MoC) was synthesized by a facile solid-state reaction method using carbon nanotubes and carbon black as carbon sources. The as-prepared MoC powders possessed irregular shape and rough surface. The EM absorption property as well as the EM parameters in the range of 2–18 GHz were investigated. It is found that the MoC powders, either carbon nanotubes or carbon black as carbon sources, showed satisfactory EM absorption performance. The powders using carbon nanotubes and carbon black as carbon source displayed the minimum reflection loss of –42.2 dB with a 1.5 mm thickness and –34.3 dB with a 3.0 mm thickness, respectively. The experimental results show that MoC is a promising EM microwave absorbing candidate, and the low-cost synthesis of MoC will be helpful for its large-scale development in EM protection field.

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Topics: Carbon black (57%), Carbon (57%), Carbon nanotube (56%) ... show more

Journal ArticleDOI: 10.1016/J.JCIS.2021.06.022
Qiqi Jing1, Jiahui Zhu1, Xiangru Wei1, Yaqian Lin1  +2 moreInstitutions (1)
Abstract: Molybdenum carbides are promising electrocatalysts for the hydrogen evolution reaction (HER). Rational design of morphology, composition and interfacial structure in Mo2C materials is essential to enhance their HER performance. Herein, an acid-base molecular assembly strategy is demonstrated for the synthesis of novel N-doped Mo2C@C core–shell nanowires (NWs) composed of mesoporous Mo2C cores with interconnected crystalline walls and ultrathin carbon shells. The strong interactions between the two precursors, adenine (Ade) and phosphomolybdic acid (PMA), lead to the formation of inter-molecular hybrid NWs during a hydrothermal process. The subsequent pyrolysis leads to confined growth of crystalline Mo2C NWs with inter-crystal mesopores (5 ~ 10 nm), formation of ultrathin carbon shells (~1.5 nm in thickness), and effective N doping. Such a structure architecture can provide abundant active sites, fast and diverse mass and electron transport paths, as well as stable reaction interfaces. The typical N-doped Mo2C@C NWs exhibit high HER performance with a low overpotential of 136 mV at 10 mA cm−2, a small Tafel slop of 58 mV dec-1, excellent durability and outstanding anti-poisoning performance against CO and H2S gases. Furthermore, the influences of several important factors, including the pyrolysis temperature, hydrothermal temperature and precursor mass ratio, on the morphology, composition and structural configuration of the resulted materials are elucidated and correlated with their HER performance. This work may provide a general strategy for the synthesis of other nanoscale metal carbides for various catalytic applications.

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Topics: Mesoporous material (53%), Overpotential (51%), Nanowire (50%)
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63 results found


Journal ArticleDOI: 10.1039/C2EE02618J
Abstract: This perspective covers the use of molybdenum disulfide and related compounds, generally termed MoSx, as electro- or photoelectrocatalysts for the hydrogen evolution reaction (HER). State of the art solutions as well as the most illustrative results from the extensive electro- and photoelectrocatalytic literature are given. The research strategies currently employed in the field are outlined and future challenges pointed out. We suggest that the key to optimising the HER activity of MoS2 is divided into (1) increasing the catalytic activity of the active site, (2) increasing the number of active sites of the catalyst, and (3) improving the electrical contact to these sites. These postulations are substantiated by examples from the existing literature and some new results. To demonstrate the electrocatalytic properties of a highly conductive MoS2 hybrid material, we present the HER activity data for multi-wall MoS2 nanotubes on multi-wall carbon nanotubes (MWMoS2@MWCNTs). This exemplifies the typical data collected for the electrochemical HER. In addition, it demonstrates that the origin of the activity is closely related to the amount of edges in the layered MoS2. The photoelectrocatalytic HER is also discussed, based on examples from literature, with an emphasis on the use of MoSx as either (1) the co-catalyst providing the HER activity for a semiconductor, e.g. Mo3S+4on Si or (2) MoS2 as the semiconductor with an intrinsic HER activity. Finally, suggestions for future catalyst designs are given.

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1,074 Citations


Open accessJournal ArticleDOI: 10.1038/NCOMMS7512
Hao Bin Wu1, Bao Yu Xia1, Le Yu1, Xin-Yao Yu1  +1 moreInstitutions (1)
Abstract: Electrochemical water splitting has been considered as a promising approach to produce clean and sustainable hydrogen fuel. However, the lack of high-performance and low-cost electrocatalysts for hydrogen evolution reaction hinders the large-scale application. As a new class of porous materials with tunable structure and composition, metal-organic frameworks have been considered as promising candidates to synthesize various functional materials. Here we demonstrate a metal-organic frameworks-assisted strategy for synthesizing nanostructured transition metal carbides based on the confined carburization in metal-organic frameworks matrix. Starting from a compound consisting of copper-based metal-organic frameworks host and molybdenum-based polyoxometalates guest, mesoporous molybdenum carbide nano-octahedrons composed of ultrafine nanocrystallites are successfully prepared as a proof of concept, which exhibit remarkable electrocatalytic performance for hydrogen production from both acidic and basic solutions. The present study provides some guidelines for the design and synthesis of nanostructured electrocatalysts. There is extensive research into non-platinum electrocatalysts for hydrogen evolution. Here, the authors report a molybdenum carbide catalyst, prepared via the carburization of a copper metal-organic framework host/molybdenum-based polyoxometalates guest system, and demonstrate its catalytic activity.

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Topics: Water splitting (53%), Molybdenum (52%), Hydrogen production (52%) ... show more

1,044 Citations


Open accessJournal ArticleDOI: 10.1002/ANIE.201207111
Heron Vrubel1, Xile Hu1Institutions (1)
14 Dec 2012-Angewandte Chemie
Abstract: Molybdenum boride (MoB) and carbide (Mo2C) are excellent catalysts for electrochemical hydrogen evolution at both pH 0 and pH 14.

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Topics: Carbide (58%), Molybdenum (57%), Water splitting (51%)

1,019 Citations


Open accessJournal ArticleDOI: 10.1038/NMAT4738
01 Jan 2017-Nature Materials
Abstract: Advances in electrocatalysis at solid-liquid interfaces are vital for driving the technological innovations that are needed to deliver reliable, affordable and environmentally friendly energy. Here, we highlight the key achievements in the development of new materials for efficient hydrogen and oxygen production in electrolysers and, in reverse, their use in fuel cells. A key issue addressed here is the degree to which the fundamental understanding of the synergy between covalent and non-covalent interactions can form the basis for any predictive ability in tailor-making real-world catalysts. Common descriptors such as the substrate-hydroxide binding energy and the interactions in the double layer between hydroxide-oxides and H---OH are found to control individual parts of the hydrogen and oxygen electrochemistry that govern the efficiency of water-based energy conversion and storage systems. Links between aqueous- and organic-based environments are also established, encouraging the 'fuel cell' and 'battery' communities to move forward together.

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Topics: Energy storage (51%)

934 Citations


Journal ArticleDOI: 10.1002/ADMA.201605838
Jing Wang1, Fan Xu1, Haiyan Jin1, Yiqing Chen1  +1 moreInstitutions (1)
01 Apr 2017-Advanced Materials
Abstract: Hydrogen has been hailed as a clean and sustainable alternative to finite fossil fuels in many energy systems. Water splitting is an important method for hydrogen production in high purity and large quantities. To accelerate the hydrogen evolution reaction (HER) rate, it is highly necessary to develop high efficiency catalysts and to select a proper electrolyte. Herein, the performances of non-noble metal-based carbon composites under various pH values (acid, alkaline and neutral media) for HER in terms of catalyst synthesis, structure and molecular design are systematically discussed. A detailed analysis of the structure-activity-pH correlations in the HER process gives an insight on the origin of the pH-dependence for HER, and provide guidance for future HER mechanism studies on non-noble metal-based carbon composites. Furthermore, this Review gives a fresh impetus to rational design of high-performance noble-metal-free composites catalysts and guide researchers to employ the established electrocatalysts in proper water electrolysis technologies.

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Topics: Hydrogen production (55%), Water splitting (54%), Electrolysis of water (53%) ... show more

926 Citations