Freestanding high-entropy phosphide electrodes for industrial-scale hydrogen evolution via far-from-equilibrium electrosynthesis

Abstract

High-entropy materials (HEMs) are a promising frontier in electrocatalysis, but the scalable fabrication of binder-free, three-dimensional electrodes remains a formidable challenge. Herein, we present a single step, far-from-equilibrium electrosynthesis strategy for constructing freestanding hierarchical high-entropy phosphide (HEP) electrodes composed of FeCoNiCuSnP. This approach enables concurrent alloying, phosphidation, dendritic structuring, and direct electrode integration under large overpotentials, simplifying fabrication while maintaining phase uniformity and hierarchical porosity. The optimized HEP electrode exhibits outstanding hydrogen evolution reaction (HER) performance in alkaline media, requiring only 52 mV overpotential to reach 10 mA cm⁻² and a low Tafel slope of 37 mV dec⁻¹. Crucially, it demonstrates remarkable long-term durability, maintaining stable operation at industrial-level current densities (∼1 A cm⁻²) and showing negligible degradation after 5000 CV cycles. Mechanistic studies reveal that the phosphorus incorporation modulates the electronic structure of multi-metallic centers, enhancing HER kinetics via a Volmer–Heyrovsky pathway. The versatility of this far-from-equilibrium electrosynthesis method is validated through the synthesis of diverse HEP compositions. This work advances a scalable framework for engineering freestanding HEM-based electrodes and provides strategic insights for realizing industrial hydrogen production.