Phosphorus-triggered lattice distortion and superlattice ordering in CoFeNiMoSn HEA enabling stably industrial water splitting

Mo- and Sn- coexsiting HEAs electrodeposited in a CE-based electrolyte. • Lattice distoration and superlattice transtion induced by P incorporation. • Phosphating enhances both structural stability and intrinsic activity. • The P-CoFeNiMoSn-1 couple requires 1.68 V to achieve 200 mA cm⁻² for industrial water splitting. Sn- and Mo-containing high-entropy alloys (HEAs) have recently emerged as promising hydrogen evolution reaction (HER) electrocatalysts, with electrodeposition representing an attractive fabrication route. However, electrodeposited HEA coatings adhere to substrates primarily via mechanical interlocking, making them prone to delamination under vigorous bubble evolution during industrial water electrolysis. A synergistic strategy combining electrodeposition with phosphating was adopted to fabricate P-doped CoFeNiMoSn HEAs (P-CoFeNiMoSn), enhancing interfacial adhesion and intrinsic activity for industrial water electrolysis. Notably, P incorporation compensates for active site loss from heat-induced superlattice transition and defect annihilation via electronic structure optimization and lattice distortion, thereby achieving enhanced stability and activity. The P-CoFeNiMoSn-1 sample with the highest P solubility exhibits bifunctional HER/OER electrocatalytic activity and stability under industrially relevant water electrolysis conditions (6 M KOH, 80 °C). The symmetric electrolyze employing P-CoFeNiMoSn-1 as both cathode and anode requires only 1.68 V to achieve a current density of 200 mA cm⁻², with a negligible potential degradation after 100 h of continuous operation. This work not only expands the electrodeposition synthesis routes for Sn- and Mo-coexisting HEAs, but also provides new insights for the design of high-performance, long-lifetime electrodes for industrial water electrolysis. Download: Download high-res image (176KB) Download: Download full-size image Fabrication of P-CoFeNiMoSn HEA and its electrocatalytic activity toward industrial water elecrolysis