N-doped carbon-wrapped MoxC heterophase sheets for high-efficiency electrochemical hydrogen production.

Highlights • N doped carbon-wrapped Mo x C heterophase sheets are synthesized via in situ carbonation. • N-Mo x C@C HSs effectively combine the respective advantages of both γ-MoC and β-Mo 2 C. • Heterostructures possess a synergistically-enhanced activity on the interface and surface of γ-MoC/β-Mo 2 C. • N-Mo x C@C HSs exhibit excellent activity and stability in acid media. Abstract Advancement of non-precious-metal catalysts for hydrogen evolution reactions (HER) with both prominent activity and excellent stability has been becoming an ongoing challenge in the following decades. Herein, N-doped carbon-wrapped molybdenum carbide heterophase (γ-MoC and β-Mo 2 C) sheets (N-Mo x C@C HSs) were prepared by a facile chemical vapor reduction (CVR) procedure and following calcination at desired temperatures. The best HER electrocatalytic activity of N-Mo x C@C HSs was detailedly examined in 0.5 M H 2 SO 4 , which exhibited a small overpotential of 172 mV (10 mA cm−2) with a Tafel slope of only 60 mV dec−1 and durability. The improved HER activities and catalytic stability were due to heterocrystal Mo x C, nitrogen doping, and carbon coating. Particularly, this study effectively combined the respective advantages of both γ-MoC and β-Mo 2 C via the interface effect and matched polarity of hydrogen adsorption. [ABSTRACT FROM AUTHOR]