Ultrasound-assisted synthesis of nickel/nickel phosphide on carbon nanotubes as highly effective electrocatalysts for hydrogen evolution reaction in alkaline solution

Nickel phosphides are considered to be excellent non-noble metal electrocatalysts for hydrogen evolution reaction (HER). However, the HER activity of nickel phosphides is still not ideal due to their relatively weak electrical conductivity. The HER performance can be enhanced by combining nickel phosphides with highly conductive materials. Here, nickel and nickel phosphide nanoparticles supported on pristine carbon nanotubes (Ni-Ni12P5/CNTs) were prepared through an ultrasonic electroless plating method. The combination of Ni-Ni12P5 active sites and the CNTs with good conductivity made the Ni-Ni12P5/CNTs good HER electrocatalytic performance with an overpotential of 120 mV at 10 mA cm−2 and a Tafel slope of 53 mV dec−1. Coupled with the outstanding chemical stability of CNTs and their strong chemical bonds with Ni-Ni12P5, the Ni-Ni12P5/CNTs electrocatalyst possessed good stability in 0.1 M KOH electrolyte solution. The ultrasonic electroless plating offers a new way for facile designing of transition metal composites with improving electrocatalytic performance toward HER.