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0D/2D Heterojunctions of Molybdenum Carbide-Tungsten Carbide Quantum Dots /N Doped Graphene nanosheets as Superior and Durable Electrocatalysts for Hydrogen Evolution Reaction

Abstract

It is of great concern to exploit and design efficient and low-cost alternatives to platinum-based electrocatalysts for hydrogen evolution reaction (HER). In this work, we report a novel well-defined 0D/2D heterojunctions of uniform molybdenum carbide-tungsten carbide quantum dots ((Mo2C)x−(WC)1−x−QDs, ~3-5 nm) /N doped graphene (NG) nanosheets with two-dimensional layered structure via a nanocasting method using KIT-6/ graphene (G) as a template. By controlling the molar ratio of Mo and W precursor, the (Mo2C)x−(WC)1−x−QDs (0<x<1)/NG nanohybrids with different Mo/W molar ratio can be achieved, which show superior HER activities to individual Mo2C/NG and WC/NG nanohybrids. The superior HER activities may attribute to the redistribution of the valence electrons of Mo and W elements, nitrogen coordinating sites, highly dispersed Mo2C-WC nanocrystals, as well as the strong coupling between Mo2C-WC nanocrystals and NG.Excitingly, the optimal (Mo2C)0.34-(WC)0.32/NG electrocatalyst exhibits as low as overpotential (100 and 93 mV) to drive a cathodic current densitie of 10 mA cm-2, a small Tafel slope (53 and 53 mV·dec-1), and a high exchange current density (0.419 and 0.804 mA·cm-2) in acidic and alkaline media, respectively. More importantly, it also shows an excellent long-term durability even 25 h of stable catalytic current at different pH values. This work is expected to provide an executable avenue to fabricate 0D/2D earth-abundant nanocomposites for HER.

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Publication details

The article was received on 02 Apr 2017, accepted on 13 Jun 2017 and first published on 14 Jun 2017


Article type: Paper
DOI: 10.1039/C7TA02864D
Citation: J. Mater. Chem. A, 2017, Accepted Manuscript
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    0D/2D Heterojunctions of Molybdenum Carbide-Tungsten Carbide Quantum Dots /N Doped Graphene nanosheets as Superior and Durable Electrocatalysts for Hydrogen Evolution Reaction

    L. Huo, B. Liu, Z. Gao and J. Zhang, J. Mater. Chem. A, 2017, Accepted Manuscript , DOI: 10.1039/C7TA02864D

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