Descriptor-Guided Design of Mo-Doped FeCoNiCu High-Entropy Alloy Electrocatalysts Surpassing Pt for Alkaline Hydrogen...

High-entropy alloys (HEAs) offer an immense compositional playground for electrocatalyst discovery. Yet, the rational navigation of this space remains elusive. Here, we introduce a multidescriptor screening strategy combining density functional theory (DFT) calculations and data analytics based on critical parameters including d-band position, water dissociation energetics, hydrogen adsorption free energies, lattice stability, and corrosion resistance. This methodology systematically evaluates FeCoNiCu-based HEAs doped with transition metals (Ti, V, Cr, Zr, Nb, Mo, and W), identifying Mo as the optimal dopant due to its ideal balance between a low water dissociation barrier (0.41 eV) and near-thermoneutral hydrogen adsorption energies at Fe-Co-Ni hollow sites. Guided by computational predictions, phase-pure Mo-rich FeCoNiCu HEA films synthesized via magnetron sputtering deliver outstanding alkaline hydrogen evolution reaction (HER) activity, with an overpotential of just 60.1 mV at 10 mA cm^-2, exceptional durability at -200 mA cm^-2 over 100 h, and performance superior to commercial Pt/C catalysts. Soft X-ray absorption spectroscopy reveals dynamic Mo-mediated electron transfer among Fe, Co, and Ni, facilitating a dual-site Volmer-Heyrovsky mechanism. This study not only establishes an earth-abundant HEA that eclipses Pt for alkaline HER but also showcases a scalable "compute-screen-make-test" paradigm that can accelerate electrocatalyst discovery across the vast HEA design space.