Advanced Deposition Methods for Mixed Metal Alloys and Hydroxides as High-Performance Catalysts for the Hydrogen Evolution Reaction
Ariel Friedman, Kevin Yang, Honghao Ge, Sanjeev Mukerjee
Abstract
Alkaline water and anion-exchange membrane electrolyzers are considered leading solutions for the large-scale production of hydrogen due to their lower capital costs. In recent years, numerous hydrogen evolution electrocatalysts have been developed, primarily by alloying nickel with other transition metals. Despite these advancements, stability remains a challenge due to the low intrinsic corrosion resistance of these alloys. In this work, we present an advanced synthesis method that incorporates an amorphous copper hydroxide phase within a nickel–copper alloy using a pH-trap mechanism. This approach prevents the formation of long-range ordered and dense catalysts, resulting in a significantly higher surface area and enhanced catalytic activity. A detailed mechanism was proposed to explain this deposition process. The use of copper eliminates corrosion risks due to its thermodynamic stability in alkaline conditions, even at relatively high potentials. Accelerated stress tests demonstrate that the NiCu catalyst is stable under both continuous and intermittent conditions, in both inert and oxygen atmospheres, positioning it as one of the most active and stable HER catalysts in alkaline media. Furthermore, the pH-trap deposition (pTD) method developed here can be applied to a variety of materials to tailor their physical and chemical properties.