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

Here we report a redox-anchoring strategy for synthesizing a non-noble metal carbide (MoCx) 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 MoCx nanoparticles during the following carbonization process. The morphology and chemical composition of the elec-trocatalysts were well characterized by BSE-SEM, TEM, XRD and XPS. The obtained MoCx-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 mAcm(-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 MoCx particles. This work may open a new way to the design and fabrication of other non-noble metal carbide nanocatalysts for various electrochemical applications.