Synthesis of oxygen-rich carbon materials as metal-free catalysts for oxygen reduction reaction in seawater electrolyte

Compared to conventional aqueous metal-air batteries, seawater batteries provide a promising strategy for the sustainable energy conversion and storage systems. However, the intricate ionic environment of seawater, in particular, Cl⁻ significantly restraint the oxygen reduction reaction (ORR) activity of the catalysts. Herein, mesoporous carbon materials with abundant oxygen-containing functional groups were simply fabricated as the cost-effective catalysts from the biowaste Ginkgo biloba, exhibiting prominent stability and ORR activity with a 4e⁻ path selectivity up to 92 % in seawater electrolyte. Structure characterization and ORR experimental results indicated the ORR performance was significantly modulated by the C-O-C in carbon matrix, and the synergistic of C-O-C and N-containing configuration may further enhance the dissociation of O-O of ∗OOH, resulting in an optimized 4e⁻ path selectivity. Additionally, the Ginkgo biloba derived catalysts displayed an overpotential of 580 mV for at 10 mA/cm² more negative than that of the previously reported commercial Ir/C in seawater electrolyte. This study highlights the synthesis of sustainable and cost-effective catalysts for seawater batteries, offering a strategy for designing metal-free catalysts of seawater battery, and promoting the advancement of sustainable energy conversion and storage technologies.