Co₂N/Co₂Mo₃O₈ Heterostructure as a Highly Active Electrocatalyst for an Alkaline Hydrogen Evolution Reaction

The development of earth-abundant electrocatalysts with high intrinsic activity, abundant active sites, and good electrical conductivity is of vital importance for the market penetration of clean energy technologies. We herein report a facile synthesis of a self-supported Co₂N/CoN/Co₂Mo₃O₈ heterostructured catalyst on cobalt foam (CF) by a hydrothermal process followed by nitridation treatment. Our first-principles calculations revealed that Co₂Mo₃O₈ and Co₂N could work in concert to provide active sites for an alkaline hydrogen evolution reaction (HER). The hierarchical and nanoporous architecture of the Co₂N/CoN/Co₂Mo₃O₈ catalyst ensured an abundance of accessible active sites. The direct growth of metalloid CoN nanoparticles on the defective Co₂Mo₃O₈ substrate endowed the catalyst with good electrical conductivity. As a consequence, the Co₂N/CoN/Co₂Mo₃O₈/CF catalyst showed extraordinarily high activity and good stability toward the alkaline HER, outperforming most existing non-precious electrocatalysts. In particular, it exhibited a comparable catalytic performance to the commercial Pt/C catalyst at a current density of 100 mA cm^-2.