Trace RuO2 nanoparticles loaded nickel-coated multi-walled carbon nanotubes to boost hydrogen evolution reaction under acidic and alkaline media

Developing low-cost catalysts with high activity for the Hydrogen Evolution Reaction (HER) is a main challenge to reduce the dependence on precious metals while maintaining the catalytic activity. In this study, nickel-plated multi-walled carbon nanotubes (Ni-MWCNTs) with a large number of active sites were selected, and Ni-MWCNTs electrocatalysts loaded with trace amounts of RuO₂ nanoparticles were prepared by annealing treatment, which exhibited excellent HER performances in both acidic and alkaline media. The RuO₂ nanoparticles loaded nickel-coated multi-walled carbon nanotubes (RuO₂@Ni-MWCNTs) had a small electrochemical impedance spectrum (EIS) and a large electrochemically active surface area (ECSA). Notably, RuO₂@Ni-MWCNTs with less than 1 % Ru content exhibited excellent catalytic activities in both acidic and alkaline solutions. The results showed that the overpotentials of RuO₂@Ni-MWCNTs were 20.2 mV (alkaline) and 73.7 mV (acidic), respectively. After stabilization at 20 mA cm^-2 for 90 h, the evaluation results showed that RuO₂@Ni-MWCNTs could maintain their catalytic efficiency without significant degradation.