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A bimetallic oxide Fe_1.89Mo_4.11O₇ electrocatalyst with highly efficient hydrogen evolution reaction activity in alkaline and acidic media.

ABSTRACT: Transition-metal Mo-based materials have been considered to be among the most effective hydrogen evolution reaction (HER) electrocatalysts. Regulating the electronic structure of Mo atoms with guest metal atoms is considered as one of the important strategies to improve their HER activity. However, introduction of guest metal elements in the vicinity of Mo sites with atomic-level hybridization is difficult to realize, resulting in the failure of the modified electronic structure of Mo sites. Herein, an Fe_1.89Mo_4.11O₇/MoO₂ material is prepared through the thermal treatment of a ferrimolybdate precursor. It exhibits a Tafel slope of 79 mV dec^-1 and an exchange current density of 0.069 mA cm^-2 in 1 M KOH medium, as well as a Tafel slope of 47 mV dec^-1 and an exchange current density of 0.072 mA cm^-2 in 0.5 M H₂SO₄ medium. Compared to original Mo-based oxides, Fe_1.89Mo_4.11O₇ with the regulated Mo electronic structure shows a more suitable Mo-H bond strength for the fast kinetics of the HER process. Density functional theory (DFT) calculations also indicate that the Mo-H bond strength in Fe_1.89Mo_4.11O₇ is similar to the Pt-H bond strength, resulting in the high kinetic activity of Mo-based HER electrocatalysts in alkaline and acidic media.

SUBMITTER: Hao Z

PROVIDER: S-EPMC6049016 | biostudies-literature | 2018 Jul

REPOSITORIES: biostudies-literature

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Publications

A bimetallic oxide Fe1.89Mo4.11O7 electrocatalyst with highly efficient hydrogen evolution reaction activity in alkaline and acidic media.

Hao Zhaomin Z Yang Shishuai S Niu Jingyang J Fang Zhiqiang Z Liu Liangliang L Dong Qingsong Q Song Shuyan S Zhao Yong Y

Chemical science 20180528 25

Transition-metal Mo-based materials have been considered to be among the most effective hydrogen evolution reaction (HER) electrocatalysts. Regulating the electronic structure of Mo atoms with guest metal atoms is considered as one of the important strategies to improve their HER activity. However, introduction of guest metal elements in the vicinity of Mo sites with atomic-level hybridization is difficult to realize, resulting in the failure of the modified electronic structure of Mo sites. Her ...[more]

PMID: 30061997

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Project description:There are many challenges associated with the fabrication of efficient, inexpensive, durable and very stable nonprecious metal catalysts for the hydrogen evolution reaction (HER). In this study, we have designed a facile strategy by tailoring the concentration of precursors to successfully obtain nickel-cobalt bimetallic sulfide (NiCo2S4) using a simple hydrothermal method. The morphology of the newly prepared NiCo2S4 comprised a mixture of microparticles and nanorods, which were few microns in dimension. The crystallinity of the composite sample was found to be excellent with a cubic phase. The sample that contained a higher amount of cobalt compared to nickel and produced single-phase NiCo2S4 exhibited considerably improved HER performance. The variation in the salt precursor concentration during the synthesis of a material is a simple methodology to produce a scalable platinum-free catalyst for HER. The advantageous features of the multiple active sites of cobalt in the CN-21 sample as compared to that for pristine CoS and NiS laid the foundation for the provision of abundant active edges for HER. The composite sample produced a current density of 10 mA cm-2 at an overpotential of 345 mV. Also, it exhibited a Tafel value of 60 mV dec-1, which predominantly ensured rapid charge transfer kinetics during HER. CN-21 was highly durable and stable for 30 hours. Electrochemical impedance spectroscopy showed that the charge transfer resistance was 21.88 ohms, which further validated the HER polarization curves and Tafel results. CN-21 exhibited a double layer capacitance of 4.69 μF cm-2 and a significant electrochemically active surface area of 134.0 cm2, which again supported the robust efficiency for HER. The obtained results reveal that our developed NiCo2S4 catalyst has a high density of active edges, and it is a non-noble metal catalyst for the hydrogen evolution reaction. The present findings provide an alternative strategy and an active nonprecious material for the development of energy-related applications.

Dataset Information

A bimetallic oxide Fe_1.89Mo_4.11O₇ electrocatalyst with highly efficient hydrogen evolution reaction activity in alkaline and acidic media.

Publications

A bimetallic oxide Fe<sub>1.89</sub>Mo<sub>4.11</sub>O<sub>7</sub> electrocatalyst with highly efficient hydrogen evolution reaction activity in alkaline and acidic media.

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