Vanadium boosted high-entropy amorphous FeCoNiMoV oxide for ampere-level seawater oxidation

A series of multi-principal elements composites (FeCoNiMoVOx-n) were synthesized on Ni foam (FeCoNiMoVOx-n/NF) to investigate the role vanadium (V) plays in improving their electrocatalytic activity for oxygen evolution reaction (OER). Surprisingly, it was discovered that the addition of V not only changed the morphology of the catalysts from microsphere to three dimensional (3D) microflower shape, but also optimized the proportion of high-valent metal species that enhance the formation of active metal oxy(hydroxide) intermediates. The as-synthesized high-entropy amorphous FeCoNiMoVOx-1.5 coated Ni foam electrode (FeCoNiMoVOx-1.5/NF) with a 3D microflower structure exhibited higher OER activity than its counterparts. It exhibited extremely low over-potentials of 216 and 236 mV which are required at 10 mA cm−2 in alkaline water and natural seawater, respectively. Particularly, this high-entropy amorphous catalyst showed long-time stability for a continuous 100-h high-performance OER at an ampere-level current density of 1 A cm−2 in alkaline natural seawater. This shows that it can be applied for large-scale seawater electrolysis.