Reconstructing the interfacial microenvironment via built-in electric fields for stable seawater oxygen reduction.

Abstract

Developing high-performance oxygen reduction reaction (ORR) electrocatalysts for direct seawater utilization is essential for marine energy conversion and practical zinc-air batteries (ZABs). Herein, Pt nanoparticles were loaded onto Ga-doped CeO2 (Pt/Ga-CeO2) through a microwave strategy. The strong interfacial interaction between Pt and Ga-CeO2 induces a robust built-in electric field, which drives charge redistribution and interfacial polarization to optimize the electronic structure of active sites and accelerate ORR kinetics. As a result, Pt/Ga-CeO2 delivers excellent ORR performance in alkaline seawater, achieving a half-wave potential of 0.89 V. In simulated seawater-based ZABs, it delivers a peak power density of 173.8 mW cm-2 and outstanding long-term stability over 750 h, while a self-assembled natural seawater battery operates continuously for 300 h. Experimental and theoretical analyses reveal that the built-in electric field regulates interfacial water structures and strengthens the hydrogen-bond network, facilitating rapid OH- transport, suppressing Cl- poisoning, and mitigating Ca/Mg precipitation. This work provides a viable strategy for designing low-Pt electrocatalysts through interfacial electric-field engineering for efficient ORR in seawater.

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