Multiscale confinement nitridation in molybdenum carbide for efficient hydrogen production

The molybdenum carbide (Mo₂C) has been regarded as one of the most cost-efficient and stable electrocatalyst for the hydrogen evolution reaction (HER) by the virtue of its Pt-like electronic structures. However, the inherent limitation of high density of empty valence band significantly reduces its catalytic reactivity by reason of strong hydrogen desorption resistance. Herein, we propose a multiscale confinement synthesis method to design the nitrogen-rich Mo₂C for modulating the band structure via decomposing the pre-coordination bonded polymer in a pressure-tight tube sealing system. Pre-bonded C/N-Mo in the coordination precursor constructs a micro-confinement space, enabling the homogeneous nitrogenization in-situ happened during the formation of Mo₂C. Simultaneously, the evolved gases from the precursor decomposition in tube sealing system establish a macro-confinement environment, preventing the lattice N escape and further endowing a continuous nitridation. Combining the multiscale confinement effects, the nitrogen-rich Mo₂C displays as high as 25% N-Mo concentration in carbide lattice, leading to a satisfactory band structure. Accordingly, the constructed nitrogen-rich Mo₂C reveals an adorable catalytic activity for HER in both alkaline and acid solution. It is anticipated that the multiscale confinement synthesis strategy presents guideline for the rational design of electrocatalysts and beyond.