Co2Ni alloy/N-doped CNTs composite as efficient hydrogen evolution reaction catalyst in alkaline medium

Abstract

Hydrogen evolution reaction (HER) is a crucial half-reaction of water splitting to produce possible future energy carrier: H2, which is directly associated with the conversion and storage of clean energy. There is a great demand on efficient earth-abundant electrocatalysts to replace Pt, especially in alkaline medium. Herein, we report Co2Ni alloy anchored on nitrogen-doped carbon nanotubes (Co2Ni alloy/N-CNTs) as an efficient alkaline HER electrocatalyst. The alloy is prepared from a straightforward hydrothermal reaction and a post-annealing process in NH3 atmosphere, which in situ reduces the nickel cobalt carbonate hydroxide precursor to alloy and brings N-doping to CNTs without changing original morphology. The as-obtained Co2Ni alloy/N-CNTs hybrids exhibit superior alkaline HER performance with a small Tafel slope of 87 mV dec−1, high exchange current density of 0.8 mA cm−2 and a low overpotential of 100 mV to drive current density of 10 mA cm−2, which is comparable to commercial Pt/C and surpasses numerous reported earth-abundant electrocatalysts. This electrocatalyst can also endure long-time HER process (>24 h). The excellent catalytic performance can be attributed to accelerated charge transfer, more exposed active sites and structural robustness which all benefit from the structural and component configuration that brought by alloy and N-doped CNTs.