Design and fabrication of bimetallic Co-Ni phosphides on WC-Co-Ni cemented carbide substrate for electrochemical hydrogen evolution reaction

Abstract

An innovative approach was proposed to recycle WC-Co-Ni cemented carbides via synthesizing bimetallic cobalt-nickel phosphides on the waste cemented carbides substrate for producing renewable hydrogen by the electrolysis of water. WC-Co-Ni cemented carbides with tunable Co/Ni ratios were prepared through the traditional powder metallurgy method. Co-Ni-P catalysts on self-supported Co-Ni porous substrates were prepared by a two-step method of etching WC grains and phosphatizing treatments. The bimetallic phosphides exhibited the excellent activities which were strongly dependent on the Co/Ni ratios. With an optimal Ni content of 50 wt% in the binder phase, the prepared materials required a low overpotential of 126 mV for achieve a current density of 10 mA cm−2. The uniformly distributed CoNiP catalyst on the Co-Ni skeleton demonstrated the highest catalytic activity due to the synergistic interaction among the abundant exposed phosphide sites, enhanced mass transfer pathways and reduced energy barrier. This work provided a feasible strategy for the recycle of waste WC-Co-Ni cemented carbides and the design of bimetallic phosphide catalysts for HER.