Confined growth of ultrafine Mo2C nanoparticles embedded in N-doped carbon nanosheet for water splitting

Because of low-cost, marvelous activity and excellent stability characteristics, nonprecious metal carbide-based catalysts are promising candidates for hydrogen evolution reaction (HER). However, inferior specific surface area and undesirable catalytic activity of pure phase carbides greatly impedes their industrialization process. Herein, ultrafine Mo2C nanoparticles embedded in N-doped carbon nanosheet has been synthesized by a facile strategy. High viscosity of guar gum alleviates the aggregation of nanocrystals by providing space-confinement effect; besides, NaCl plays two roles: (1) hard template directing the formation of carbon nanosheet; (2) molten salt adjusting the nucleation and growth process of Mo2C to ensure the formation of ultra-small Mo2C nanoparticles. Two-dimensional sheet-like carbon accelerates the electron transfer, and rich heterojunction between ultrafine Mo2C and N-doped carbon facilitates boosting the HER catalytic activity. The prepared Mo2C/NCS with optimized composition exhibit excellent electrocatalytic activity and stability both in acidic (189 mV at a current density of 10 mV/cm(2) with a Tafel slope of 61.2 mV/dec) and alkaline medium (142 mV at a current density of 10 mV/cm(2) with a Tafel slope of 56.1 mV/dec). This work may provide insight for developing economic and high-efficient catalysts for water splitting. (C) 2020 Elsevier B.V. All rights reserved.