High-entropy spinel (FeCoNiMnAl)3O4 with three-dimensional microflower structure for stable seawater oxidation.

In this study, high-entropy spinel (FeCoNiMnAl) 3 O 4 catalyst with a three-dimensional(3D) layered microflower structure assembled by nanosheets grown on Ni foam (NF) is synthesized for stable seawater oxidation. Density functional theory (DFT) calculations indicate that it has a strong charge transfer capability, thereby reducing the energy barrier and boosting the reaction. As a result, a low oxygen evolution reaction (OER) overpotential of 274 mV@50 mA cm−2 is achieved with a small Tafel slope of 47.79 mV dec−1 in 1 M KOH solution. Notably, DFT calculations further verify that it shows stronger adsorption of OH than Cl. As expected, the required overpotentials are still as low as 284 and 295 mV@50 mA cm−2 in alkaline simulated seawater and natural seawater electrolytes. Also, it exhibits excellent stability and corrosion resistance, maintaining stable OER activity over 50 h at 500 mA cm−2 in alkaline natural seawater, which has the potential to realize industrial electrochemical seawater splitting. [Display omitted] • A high-entropy spinel (FeCoNiMnAl) 3 O 4 catalyst is obtained for seawater oxidation. • The catalyst exhibits low OER overpotential of 295 mV@ 50 mA cm−2 in seawater electrolyte. • The catalyst displays long-term stability in alkaline seawater electrolyte. • DFT calculations verify strong synergistic effect with stronger adsorption of OH than Cl. • The driven voltage of assembled electrolyzer by using the catalyst is 1.6 V at 80 °C. [ABSTRACT FROM AUTHOR]