Patterned High-Entropy Alloy Electrocatalyst for Efficient Hydrogen Evolution via Laser-Directed Bubble Printing

High-entropy alloys (HEAs) provide broad compositional tunability for electrocatalysis, but conventional synthesis is energy-intensive, batch-limited, and requires postprocessing. A laser-directed bubble-printing method is introduced for the direct, ambient-condition fabrication of HEA catalysts on conductive substrates with microscale precision. Unlike conventional powder-based syntheses, bubble-printing enables in situ substrate growth through optothermal bubble confinement, combining ion accumulation and localized hydrothermal reactions. Using this approach, CuFeRhPdPt alloys are synthesized that exhibit a short-range ordered face-centered cubic microstructure, as confirmed by scanning transmission electron microscopy and selected-area electron diffraction. The printed alloys demonstrate efficient hydrogen evolution reaction (HER) activity in acidic media, achieving overpotentials of 5.23 and 18.49 mV at −10 and −200 mA·cmgeo–2, respectively, with a corresponding Tafel slope of 27.3 mV·dec–1. These results demonstrate competitive HER performance relative to reported multimetallic catalysts under comparable conditions. Bubble-printing enables high-throughput discovery of HEA electrocatalysts, with tunable stoichiometry and combinatorial arrays applicable to reactions beyond the HER.