Chemical short-range order in multi-principal element alloy with ordering effects on water electrolysis performance

The superior electrocatalytic activity of multi-principal element alloys (MPEAs) is typically attributed to synergistic effects of their multi components in random solid solutions. Strategies to control the functional atoms with a chemically ordered atomic distribution and the specific atomic configuration in the MPEAs remain a challenging research topic. Here, we have discovered non-random, chemical short-range order (CSRO) in a Fe₁₀Co₅Ni₁₀Cu₁₅Al₆₀ MPEA induced by magnetic characteristics of elements, leading to ultralow overpotential for dual-electrode water splitting in alkaline condition. Atomic-resolution imaging and elemental mapping assisted by statistical analysis and density functional theory (DFT) simulations revealed that CSRO in the MPEA originated from the nearest-neighbor preference of M-Cu (M = Fe, Co, Ni, and Al) pairs and repulsion of same-element pairs (Fe-Fe, Co-Co, Ni-Ni, Cu-Cu, and Al-Al). Such preferential atomic pairs facilitated H₂O/H* adsorption/desorption during the hydrogen evolution reaction and reduced the energy barrier for the rate-determining step of the oxygen evolution reaction, thereby promoting excellent overall water splitting performance. The achieved current density (130 mA cm⁻²) of the low-cost MPEA was ∼4 times higher than that of the Pt/C||RuO₂ dual-electrode system (32 mA cm⁻²) at a cell voltage of 2.0 V. The concept of CSRO in MPEAs offers new insights into their multi-functional applications, potentially spurring the development of numerous high-performance MPEA-based devices for the energy and environmental sectors.