Nitrogen-rich carbon coupled multifunctional metal oxide/graphene nanohybrids for long-life lithium storage and efficient oxygen reduction

Graphene-based nanohybrids are very appealing materials for energy storage and conversion applications. Strong binding of nanostructured guest materials with favorable properties and coupling effect to graphene is highly desirable to enhance the structural stability, interfacial characteristics and reaction kinetics of the nanohybrids. In this work, we present the fabrication of novel multifunctional nanohybrids by chemically coupling ultrafine metal oxide (e.g., Fe3O4) nanoparticles to reduced graphene oxide (rGO) with a thin layer of nitrogen-rich carbon (CNx) as 2D crosslinker. The combination and synergy of rGO and CNx layer with extremely high N content (59 wt%) modify the interfacial properties for homogenous and firm growth of Fe3O4 nanoparticles on rGO without compromising the intrinsic properties of rGO. When evaluated as anode materials in lithium-ion batteries, Fe3O4/CNx/rGO nanohybrids exhibit very long lifespan of 1000 cycles with high capacities at high current densities of 2-5 A g(-1), as well as excellent high-rate capability of up to 10 A g(-1). As a non-precious metal catalyst, these nanohybrids also exhibit comparable catalytic activity towards oxygen reduction reaction to commercial Pt/C catalyst in terms of high electron transfer number, high current density, good durability and methanol tolerance capability. (C) 2015 Elsevier Ltd. All rights reserved.