Hydroxyl functional group activates strong metal–support interactions enabling efficient oxygen reduction reaction in saline water

Abstract

The development of high-performance and stable electrocatalysts for the oxygen reduction reaction (ORR) in seawater electrolytes is of great significance for advancing the practical application of zinc–air batteries (ZABs) in seawater environments. In this work, we successfully synthesized the Pt-CNTs-OH catalyst by anchoring platinum nanoparticles (Pt NPs) on hydroxyl-functionalized carbon nanotubes (CNTs-OH) via a fast microwave-assisted method. Theoretical calculations indicate that surface-modified hydroxyl (–OH) groups can modulate the electronic configuration of Pt via metal–support interactions, weakening the Pt–O bond strength, facilitating *OH desorption from the Pt-CNTs-OH surface, and lowering the energy barrier of the rate-limiting step of the ORR. Characterizations confirm that the electron-rich –OH group interacts synergistically with Pt, forming an electron-rich protective interfacial layer that repels Cl⁻ to enhance salt corrosion resistance. Moreover, highly electronegative –OH groups strengthen the binding of Pt NPs to CNTs-OH, ensuring structural stability. Consequently, Pt-CNTs-OH demonstrates an E_1/2 of 0.89 V when tested in alkaline seawater. When employed as the cathode catalyst for ZABs featuring an alkaline seawater electrolyte, this material delivers a maximum power density of 166 mW cm⁻² and maintains stable operation for 855 hours.