3D walnut-shaped TiO2/RGO/MoO2@Mo electrode exhibiting extraordinary supercapacitor performance

Abstract

Rational architectural design is the key to improve specific capacitance. Herein, we present a facile one-step hydrothermal process for the fabrication of a TiO₂/RGO/MoO₂ composite with an unprecedented 3D walnut-shaped hierarchical nanostructure, in which amorphous TiO₂ is decorated on the RGO (reduced graphene oxide)/MoO₂ surface via a Mo-involved in situ growth route on Mo net (TiO₂/RGO/MoO₂@Mo). This 3D structure coated with ultrafine arched nanorods is a great breakthrough in electrochemical performances of TiO₂– or MoO₂-based electrodes as it exhibits an extraordinary areal capacitance of 3927 mF cm⁻² at 3 mA cm⁻² (i.e. 1636 F g⁻¹ at 1.25 A g⁻¹) with only 3.5% capacitance loss after 5000 cycles. Such an excellent performance is benefitted from the following factors: (i) amorphous TiO₂ sculptured MoO₂ blocky particles supply more active-site accessibility and facilitate the accommodation of volume expansion. (ii) Arched MoO₂ nanorods as well as the walnut-shaped spheres of the composite provide electron transfer paths. (iii) RGO is a soft scaffold, which relieves the volume expansion during the charge/discharge processes.