Ultrafine VN nanoparticles confined in Co@N-doped carbon nanotubes for boosted hydrogen evolution reaction

Development of highly active, durable electrocatalysts involving cheap and earth-abundant non-precious metals for the electrocatalytic hydrogen evolution reaction (HER) is of great significance for green hydrogen fuel production. Herein, we report a novel ultrafine VN nanoparticle (2–4 nm) dispersedly confined in Co-encapsulated N-doped carbon nanotubes (VN/Co@NCNT) by a facile one-pot NH3-free pyrolysis method. When applied for the electrocatalytic HER, the as-obtained VN/Co@NCNT material exhibits greatly improved catalytic activity compared to bulk VN and Co@NCNT counterparts, with a quite low overpotential of 180 mV at 10 mA cm−2 (VN: 342 mV; Co@NCNT: 313 mV), accompanying a remarkable catalytic durability for over 60 h and approximately 100% Faradaic efficiency in alkaline media. The enhanced electrocatalytic HER performance of VN/Co@NCNT can be mainly attributed to the exposed high-density catalytically active sites of ultrafine VN nanoparticles, the fast mass and electron transport over Co-embedded graphitic carbon nanotubes, as well as the enhanced electrical conductivity by the graphitic and pyridinic N-doping effects. [Display omitted] •A facile one-pot NH3-free pyrolysis approach is reported to synthesize carbon tube-supported ultrafine VN nanoparticles.•The ultrafine nanostructure of VN favors the full exposure of catalytically active sites on its surface.•The as-obtained material can function as a highly active and stable nonprecious metal containing electrocatalyst of HER.•The findings put forward new insights into the rational design of efficient VN-based HER electrocatalysts.