Coupling high entropy oxide with hollow carbon spheres by rapid microwave solvothermal strategy for boosting oxygen...

High entropy oxides (HEOs) are promising oxygen evolution electrocatalysts due to the unique structure, inherent tunability, as well as excellent catalytic activity and stability. Herein, (FeCoNiCrMn)₃O₄ nanoparticles coupling with the hollow-mesoporous carbon spheres (HCS) has been designed and fabricated by a rapid and efficient microwave solvothermal followed by annealing. The prepared (FeCoNiCrMn)₃O₄ nanoparticles are highly dispersed on the HCS surface with an average particle size of approximately 3.3 nm. The composite with large surface areas can facilitate mass transfer and gas release, and it allows more active sites to be exposed. The obtained (FeCoNiCrMn)₃O₄/hollow-mesoporous carbon sphere composite catalyst with the optimal HEO load (HEO/HCS-3) exhibits outstanding oxygen evolution reaction (OER) electrocatalytic performance with a low overpotential of 263 mV at 10 mA cm^-2, and a small Tafel slope of 41.24 mV dec^-1, better than the pure (FeCoNiCrMn)₃O₄ and commercial RuO₂ catalyst. The long-term durability of HEO/HCS-3 is also achieved by continuous electrolysis in 1 M KOH solution for more than 100 h. The outstanding catalytic performance of the composite can be ascribed to the clever structural design and the well-matched synthetic method. This research can guide the construction of high-efficient OER catalysts.