Plasmonic Enhancement in an Earth-Abundant CuNi Catalyst for Alkaline Hydrogen Evolution Reaction

Hydrogen generation in alkaline media is essential for scalable, sustainable water electrolysis but is limited by sluggish hydrogen evolution reaction (HER) kinetics that prevent earth-abundant catalysts from matching platinum. We present a noble-metal-free, light-responsive CuNi electrocatalyst that couples the plasmonic excitation of Cu with the catalytic activity of Ni. The optimized Cu-Ni interface supports strong visible plasmonic absorption near 625 nm and favorable charge redistribution for water dissociation. Under illumination, the CuNi catalyst achieves an overpotential of 47 mV at -10 mA cm^-2, surpassing Pt under identical operating conditions and doubling efficiency relative to dark operation. Mechanistic analyses reveal that plasmon excitation drives hot-electron injection into Ni active sites as well as photothermal enhancement of mass transport, establishing a light-driven catalytic regime beyond conventional electrocatalysis. This work demonstrates the first visible-light-driven HER catalyst surpassing Pt with a noble-metal-free design, outlining a scalable pathway toward sustainable photoelectrocatalytic hydrogen production.