Enthralling Anodic Protection by Molybdate on High-Entropy Alloy-Based Electrocatalyst for Sustainable Seawater Oxidation.

ABSTRACT

Efficient and sustainable seawater electrolysis is still limited due to the interference of chloride corrosion at the anode. The designing of suitable electrocatalysts is one of the crucial ways to boost electrocatalytic activity. However, the approach may fall short as achieving high current density often occurs in chlorine evolution reaction (CER)-dominating potential regions. Thereby, apart from developing an OER-active high-entropy alloy-based electrocatalyst, the present study also offers a unique way to protect anode surface under high current density or potential by using MoO4 2- as an effective inhibitor during seawater oxidation. The wide variation of d-band center of high-entropy alloy-based electrocatalyst allows great oxygen evolution reaction (OER) proficiency exhibiting an overpotential of 230 mV at current density of 20 mA cm-2. Besides, the electrocatalyst demonstrates impressive stability over 500 h at high current density of 1 A cm-2 or at a high oxidation potential of 2.0 V versus RHE in the presence of a molybdate inhibitor. Theoretical and experimental studies reveal MoO4 2- electrostatically accumulated at anode surface due to higher adsorption ability, thereby creating a protective layer against chlorides without affecting OER.