Constructing a hollow core-shell structure of RuO2 wrapped by hierarchical porous carbon shell with Ru NPs loading for supercapacitor

Abstract

Hollow core-shell structure nanomaterials have been broadly used in energy storage, catalysis, reactor, and other fields due to their unique characteristics, including the synergy between different materials, a large specific surface area, small density, large charge carrying capacity and so on. However, their synthesis processes were mostly complicated, and few researches reported one-step encapsulation of different valence states of precious metals in carbon-based materials. Hence, a novel hollow core-shell nanostructure electrode material, RuO2@Ru/HCs, with a lower mass of ruthenium to reduce costs was constructed by one-step hydrothermal method with hard template and co-assembled strategy, consisting of RuO2 core and ruthenium nanoparticles (Ru NPs) in carbon shell. The Ru NPs were uniformly assembled in the carbon layer, which not only improved the electronic conductivity but also provided more active centers to enhance the pseudocapacitance. The RuO2 core further enhanced the material's energy storage capacity. Excellent capacitance storage (318.5 F·g−1 at 0.5 A·g−1), rate performance (64.4%) from 0.5 A·g−1 to 20 A·g−1, and cycling stability (92.3% retention after 5000 cycles) were obtained by adjusting Ru loading to 0.92% (mass). It could be attributed to the wider pore size distribution in the micropores which increased the transfer of electrons and protons. The symmetrical supercapacitor device based on RuO2@Ru/HCs could successfully light up the LED lamp. Therefore, our work verified that interfacial modification of RuO2 and carbon could bring attractive insights into energy density for next-generation supercapacitors.