Carbon/carbon nanotube-supported RuO₂ nanoparticles with a hollow interior as excellent electrode materials for supercapacitors

Tailoring the internal structure of nanomaterials is an effective way to enhance their performance for a given application. Herein, a core-shell templated approach is demonstrated to fabricate carbon or carbon nanotube-supported hollow structured RuO₂ nanoparticles as excellent electrode materials for supercapacitors. This strategy involves the synthesis of core-shell Ag-Ru nanoparticles, and subsequent loading on carbon or carbon nanotube support. Then the Ag component is removed from the core region using saturated aqueous Na₂S solution to generate hollow structured Ru nanoparticles on carbon or carbon nanotube support, which are then converted into RuO₂ with intact hollow structure by thermal treatment in air. In particular, the as-prepared carbon or carbon nanotube-supported hollow RuO₂ nanoparticles for a supercapacitor adopting the H₂SO₄ electrolyte exhibit high specific capacitances of 817.1 and 819.9 Fg^-1, respectively, at a current density of 0.2 Ag^-1. The specific capacitances for hRuO₂/C, hRuO₂/CNT nanocomposites were maintained at 805.8 and 770.2 Fg^-1, respectively, at current density of 0.5 Ag^-1 with good cycle stability. The comparison in electrochemical performance between the hollow structured RuO₂ and their core-shell counterparts for a capacitor manifests that the preparation of RuO₂ nanoparticles with hollow interiors is favorable for the enhancement in their capacitive behavior.