Strategically designed trimetallic catalyst with minimal Ru addresses both water dissociation and hydride poisoning barriers in alkaline HER

Abstract

The major issue with the alkaline hydrogen evolution reaction (HER) is the poor kinetics emerging from the tedious water dissociation coupled Volmer step and efficient discharge of protons, resulting from the dissociation of water before they can be neutralized by the abundant hydroxide anions. In this work, we strategically developed a catalyst to overcome the two above-mentioned issues. The single-step electrodeposition of a CoMoRu trimetallic catalyst supported on a carbon cloth substrate was performed and the resultant catalytic electrode was screened for the HER in 1.0 M KOH. The Co component of the catalytic electrode promoted water dissociation, while Ru with a relatively smaller loading efficiently discharged protons, resulting in the evolution of H₂. In addition, the Mo component possessed appropriate electronic configuration to assist the optimal bonding of H_ad to the catalytic sites and prevent Ru from getting poisoned by the hydride intermediates. Overall, CoMoRu/CC delivered excellent activity and outperformed the commercial Pt/C with 20-times the quantity of Pt than Ru in our CoMoRu/CC. In particular, CoMoRu/CC demanded just 248 mV to deliver a current density of −100 mA cm⁻², while the controls demanded more than 380 mV. Moreover, CoMoRu/CC also showed the lowest Tafel slope (120 mV dec⁻¹) among the samples, implying the facilitated kinetics due to the presence of Co and Mo with the H₂-evolving Ru.