Nanostructured Pt-NiFe Oxide Catalyst for Hydrogen Evolution Reaction in Alkaline Electrolyte Membrane Water Electrolyzers

Abstract

The hydrogen evolution reaction (HER) is a key chemical reaction as part of water splitting to produce clean hydrogen. Pt is the best catalyst for HER in acidic media, but its activity is greatly reduced under alkaline conditions. Therefore, improving the sluggish alkaline HER kinetics is urgently needed to achieve highly efficient hydrogen production by alkaline electrolyte membrane (AEM) water electrolysis. Herein, Pt nanocatalysts supported on Ni-Fe oxides were synthesized by a modified colloidal method, which exhibit approximately 4 times higher HER specific activity and more than 2 times higher mass activity compared to a commercial Pt/C catalyst in alkaline solution, showing the potential to reduce Pt loading by half on the cathode side of AEM water electrolyzers. The high HER activity corresponds to the large amount in the Ni-Fe oxide phase accompanied by a moderate hydrogen binding energy with Pt. Keeping Pt and Ni-Fe oxides in separate phases is more effective than forming a Pt-Ni-Fe alloy in improving HER activity. Experimental results and density functional theory calculations indicate that the NiFe oxide not only promotes water dissociation but also facilitates the hydrogen adsorption/desorption process on Pt, thereby accelerating the overall kinetics of alkaline HER. The identification of these electrocatalytic trends for metal/oxide modified Pt catalysts provides fundamental insights that can guide the design and synthesis of efficient alkaline HER catalysts for hydrogen production.