Exploring the hydrogen evolution capabilities of earth-abundant ternary metal borides for neutral and alkaline water-splitting

Amorphous ternary metal borides in the form of Co-M-B (where, M = Fe, Ni, Cu, Mo, Mn, W or Cr) were developed for electrocatalytic hydrogen evolution in neutral and alkaline solutions. Except for Co-Cr-B, all the Co-M-B catalysts showed better hydrogen evolution rate than Co-B, with the lowest overpotential of 95 mV and 67 mV (at 10 mA/cm2) recorded for optimized Co-Mo-B catalyst, in pH 7 and pH 14, respectively. The reasons for enhancement in electrocatalytic rate, with inclusion of a second metal in Co-B, were investigated by considering several material related factors, such as, physical and electrochemical surface area, turn-over frequency, surface elemental states & composition and charge-transfer resistance. These experimental results were complemented with computational investigations to identify the most suitable sites for hydrogen adsorption and determine their H-adsorption energies. In the end, industrial feasibility of the developed Co-M-B catalysts was illustrated by performing stability and recycling tests.