An Oxygenophilic Atomic Dispersed Fe-N-C Catalyst for Lean-Oxygen Seawater Batteries

摘要

A constant energy supply is crucial for the exploration of deep-sea extreme environments, and a self-powered energy conversion device is ideal for this situation. Dissolved-oxygen seawater batteries (SWBs) that generate electricity by reducing the dissolved oxygen are promising candidates but the ultralow oxygen concentration in deep sea limits the reaction kinetics. As a result, oxygenophilic electrocatalysts for lean-oxygen conditions are urgently needed. A microwave heating method is reported that achieves the ultrafast synthesis of atomic dispersed Fe-N-C catalyst (Fe-N-graphene (G)/carbon nanotube (CNT)), which possesses high activity and strong oxygenophilic interface between graphene and CNTs. DFT calculations and experimental results both show that the high oxygenophilicity is due to the double-adsorption sites on the G/CNT interface, and the high activity Fe-N-4 active sites is caused by the charge separation. Fe-N-G/CNT catalysts have an outstanding oxygen reduction reaction (ORR) performance in both O-2-saturated alkaline medium and neutral seawater with half-wave potentials (E-1/2) of 0.929 and 0.704 V, respectively, far better than commercial Pt/C. A SWB shows excellent performance in lean-oxygen seawater (approximate to 0.4 mg L-1), with a discharge voltage of 1.18 V at 10 mA cm(-2). These results suggest a critical role for oxygenophilic catalyst specifically for SWBs under lean-oxygen conditions.