A stable oxygen evolution splitting electrocatalysts high entropy alloy FeCoNiMnMo in simulated seawater

Stabilizing anode for oxygen evolution (OER) in chlorine-containing electrolytes is a significant challenge. Adding corrosion inhibitors in electrolytes can alleviate this problem, but the type and dosage of corrosion inhibitors need a lot of exploration, and side reactions may occur to reduce current efficiency. Herein, we prepared a FeCoNiMnMo High entropy alloy (HEA) electrode for OER in simulated seawater without corrosion inhibitors. It exhibits great electrocatalytic activity (overpotential (η) = 237 mV at 10 mA cm–2) and excellent stability (200 h at 100 mA cm–2). Experiments and Density Functional Theory (DFT) calculation show that the protective layer containing K2MoO4 is the crucial factor for chlorine resistance of FeCoNiMnMo electrode. The tightly adsorbed state of Cl– and K2MoO4 ensures that other oxides are not corroded. And the externally added K2MoO4 cannot protect the electrode. In addition, the high-entropy effect of HEA reduces the dissolution of the alloy. This work provides an efficient way to prepare a noble-free HEA catalyst that can stabilize oxygen evolution in corrosive electrolytes.