N-Graphene-Metal-Oxide(Sulfide) hybrid Nanostructures: Single-step plasma-enabled approach for energy storage applications

Hybrid graphene-based nanostructures are considered promising materials for energy storage applications. However, the synthesis of high-quality hybrid graphene nanostructures at high yields is challenging. In the present work we propose a novel, single-step microwave plasma-enabled approach to synthetize customizable hybrid graphene-based nanostructures at high-yield while preserving their quality. Hybrid N-graphene (nitrogen-doped graphene) metal-based nanostructures, for instance, can be produced at a rate of similar to 19 mg/min. The high energy density region of a microwave plasma provides sufficient energy and building particles fluxes towards the low-energy density plasma afterglow for the processes of assembly and growth of N-graphene sheets. Simultaneously, a controlled jet of metal-oxide(-sulfide) microparticles is sprayed into the plasma afterglow region where they bind to N-graphene sheets. Methane/methylamine are used as carbon and nitrogen precursors, combined with micron-sized MnO2 and oxy-MnS particles to synthesize the hybrid structures. As a result, nanosized (similar to 10-30 nm) MnOx particles decorated N-graphene (4.6 at. N%) and oxidized metal sulfide anchored N-graphene sheets (3.1 at. N%) are produced at atmospheric conditions. High structural quality and distribution of metal-based nanostructures on N-graphene sheets are revealed using transmission and scanning electron microscopes and other advanced spectroscopic techniques. Finally, an electrode for supercapacitor based on the Ngraphene-metal-oxide(sulfide) hybrid nanostructures is developed with promising specific capacitances (similar to 273 F. g(-1)- at 0.5 A.g(-1)). The described chemically engineered process is one of the fastest approaches reported for designing the high-quality hybrid nanostructures produced at a high-yield, and as such, is expected to provide a high impact on the design of electrode materials for sustainable energy storage systems.

Automated summary

This paper proposes a novel approach using microwave plasma to synthesize high-yield and high-quality hybrid graphene-based nanostructures. The method can produce customizable electrode materials with well-structured metal-based nanostructures on graphene nanosheets.