Cathodic plasma driven self-assembly of HEAs dendrites by pure single FCC FeCoNiMnCu nanoparticles as high efficient electrocatalysts for OER

High-entropy alloys (HEAs) have been recognized as promising catalysts enabling the improvement of the sluggish kinetics of oxygen evolution reaction (OER). Nevertheless, the fabrication of nano HEAs at large-scale is still challenging. Herein, for the first time to the best of our knowledge, cathodic plasma electrolysis deposition (CPED) is utilized to develop FeCoNiMnCu HEA dendrites which are self-assembled by single HEA nanoparticles. These particles were examined to be face-centered cubic, having a size less than 40 nm and being randomly stacked together porously. The dendrites appear a 3D structure and leave a gap of approximately 5 um in between, leading to a significantly large surface area. Along with the highly deformed lattices with defects, this unique nanostructure achieves the very high efficient OER performance with an overpotential of 280 mV at 10 mA cm⁻² and a low Tafel slope of 59 mV dec⁻¹ in 1.0 M KOH solution. FeCoNiMnCu HEA dendrites also show outstanding electrochemical stability and are claimed that no compositional reorganization occurs after the long-term durability test. This work provides a new route to synthesize nanoscale HEAs for energy storage and conversion in a large-scale base for practical commercialization.