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

Abstract

• FeCoNiMnMo electrode possesses a low overpotential of 237 mV at j=10 mA cm −2 and great stability of 200 h at 100 mA cm −2 in simulated seawater. • The composite protective layer with K 2 MoO 4 is the key factor for the electrode in chlorine resistance. • K 2 MoO 4 has the strongest adsorption energy with Cl − , which protects other oxides from Cl − corrosion. • Only the self-generated K 2 MoO 4 can protect the electrode by repelling Cl − . • The high entropy effect greatly inhibits the dissolution of metals. 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 K 2 MoO 4 is the crucial factor for chlorine resistance of FeCoNiMnMo electrode. The tightly adsorbed state of Cl – and K 2 MoO 4 ensures that other oxides are not corroded. And the externally added K 2 MoO 4 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.