Interfacial charge redistribution in ultrafine ruthenium nanoparticle-decorated N-modified carbon catalysts accelerates oxygen redox for lithium-oxygen batteries

Aprotic lithium-oxygen (Li-O2) batteries are severely limited by slow cathode reaction kinetics and large polarization. Herein, we design and prepare a Mott-Schottky catalyst by uniformly embedding ultrafine Ru nanoparticles on the nitrogen-doped carbon (Ru@NC) nanoflakes to accelerate oxygen redox kinetics of Li-O2 batteries. The Mott-Schottky effect of Ru@NC drives the spontaneous electron rearrangement in the NC matrix and induces a strong built-in electric field at heterointerfaces, which accelerates the activation and conversion of oxygen intermediates. The obtained Ru@NC possesses rich Mott-Schottky heterointerfaces and defective carbon structures, which provide extensive adsorption and nucleation sites. More importantly, Ru@NC manifests moderate affinity for the intermediate LiO2, inducing formation of unique nanosheet-like Li2O2 with low Li2O2/cathode interfacial impedance, which further enhances oxidation kinetics. These enable the Li-O2 battery with Ru@NC to deliver a remarkably reduced polarization of 0.89 V, superior rate performance, and prolonged lifespan of over 200 cycles. This work will provide valuable guidelines for engineering advanced electrocatalysts for high-performance Li-O2 batteries and beyond.