Monodispersed bi-metallic phosphide anchoring on CNTs with enhanced stability and electrocatalytic HER performance at a wide PH range

Designing efficient, stable, and inexpensive catalysts for water splitting was critical for efficient, sustainable energy conversion. Here, a one-pot hot-colloidal route was adopted to synthesize the mono-dispersed NiCoP catalyst with a particle size of∼5.0 nm. To further improve the structural stability and electronic conductivity of the catalysts, carbon nanotubes (CNTs) were introduced. The theoretical calculations suggested that a synergistic effect between Ni and Co in the NiCoP catalyst not only leads to an obvious charge redistribution but also facilitates the electron transfer from the surface to the reactant intermediates, being responsible for the optimal ΔGH* of the catalyst. As a result, NiCoP/CNTs exhibited good HER performance both in acidic and alkaline electrolytes. The overpotentials under alkaline and acidic electrolytes were 110 mV and114 mV at a current density of 10 mA cm−2, respectively. In comparison with pristine Ni2P(Co2P), the overpotential of NiCoP/CNTs in acidic and alkaline electrolytes was reduced by 50(24) and 62(30) mV at the current density of 10 mA cm−2. Even at the current densities of 50 and 200 mA cm−2, NiCoP/CNTs still retains a much lower overpotential than other samples. Our results revealed the important roles of the synergistic effect between the transition metals and the interaction between CNTs and the phosphides, which provides some useful information for the design and optimization of relevant HER catalysts.