Novel Mechanically-Alloyed Cu–La–P Ternary Alloy Electrocatalysts for the Alkaline Hydrogen Evolution Reaction

Abstract

Transition metal phosphides, such as Cu3P, are of research interest as hydrogen evolution electrocatalysts due to a combination of good intrinsic activity and good stability. Rare earth-transition metal alloying is known to improve electrocatalytic performance, especially by the formation of intermetallic phases. Current transition metal phosphide electrocatalyst manufacturing methods are not capable of forming these intermetallic phases. Mechanical alloying is a promising technique to synthesize these intermetallic phases. Alloy powders of Cu3P, Cu19La5P12, and a novel multi-phase Cu74La4P22 composition were prepared using mechanical alloying and evaluated as electrocatalysts for the alkaline hydrogen evolution reaction on a geometric and intrinsic area basis. On an intrinsic basis, the novel Cu–La–P composition demonstrated excellent Tafel performance of 69.4 mV dec−1. Tafel slope, exchange current density, and overpotential data demonstrated the importance of spillover effects in multiphase Cu3P/Cu19La5P12 surface structures. These results suggest that Cu–La–P alloys are promising potential catalysts for electrochemical hydrogen production, and mechanical alloying of rare earth elements is an effective technique for improving the electrochemical performance of transition metal phosphides.