Effect of Cobalt Composition on Electrochemical Behavior of Platinum-Based Catalyst towards Hydrogen Evolution Reaction

The hydrogen production from water electrolysis is of interest as a renewable energy generation technology. However, the high price of noble platinum (Pt) catalysts for the hydrogen evolution reaction (HER) is a big challenge to use it. Herein, we fabricate cost-effective CoPt bimetallic alloys and explore the effect of Co composition on the electrochemical behavior of such alloys, which has been rarely reported. A series of Co_1-xPt_x (x = 0.25; 0.5; 0.75) alloys are prepared via a room-temperature chemical reduction route without using any surfactants/stabilizers that exhibit a uniform distribution in small particle sizes (ca. 3 nm) on the carbon surface. In terms of the HER, the incorporation of a suitable Co proportion into the Pt lattices enhance significantly the HER performance in an acidic environment. For instance, the Co_0.5Pt_0.5 NPs/C catalyst displays a low onset potential (16.67 mV) and a small Tafel slope (19.60 mV dec^-1), which is different from other Co_1-xPt_x catalysts and commercial C-supported Pt (NPs) catalyst. This research result not only supplies a facile strategy to synthesize alloys but also guides the choice of a suitable proportion of transition metal into Pt lattice for electrochemical reactions in green energy storage and conversion technologies.