A Redox-anchoring Approach to Well-dispersed MoC_x /C Nanocomposite for Efficient Electrocatalytic Hydrogen Evolution

Here we report a redox-anchoring strategy for synthesizing a non-noble metal carbide (MoC_x ) nanocomposite electrocatalyst for water electrolysis in acidic media, using glucose and ammonium heptamolybdate as carbon and Mo precursors, respectively, without the need of gaseous carbon sources such as CH₄ . Specifically, the aldehyde groups of glucose are capable of reducing Mo⁶⁺ to Mo⁴⁺ (MoO₂ ), and thus molybdenum species can be well anchored by a redox reaction onto a carbon matrix to prevent the aggregation of MoC_x nanoparticles during the following carbonization process. The morphology and chemical composition of the electrocatalysts were well characterized by BSE-SEM, TEM, XRD and XPS. The obtained MoC_x -2 sample showed a reasonably high hydrogen evolution reaction (HER) activity and excellent stability in an acidic electrolyte, and its overpotential required for a current density output of 20 mA cm^-2 is as low as 193 mV. Such a prominent performance is ascribed to the excellent dispersity and nano-size, and the large reactive surface area of MoC_x particles. This work may open a new way to the design and fabrication of other non-noble metal carbide nanocatalysts for various electrochemical applications.