Design and Synthesis of Hierarchical SiO₂@C/TiO₂ Hollow Spheres for High-Performance Supercapacitors

TiO₂ has been widely investigated as an electrode material because of its long cycle life and good durability, but the relatively low theoretical capacity restricts its practical application. Herein, we design and synthesize novel hierarchical SiO₂@C/TiO₂ (HSCT) hollow spheres via a template-directed method. These unique HSCT hollow spheres combine advantages from both TiO₂ such as cycle stability and SiO₂ with a high accessible area and ionic transport. In particular, the existence of a C layer is able to enhance the electrical conductivity. The SiO₂ layer with a porous structure can increase the ion diffusion channels and accelerate the ion transfer from the outer to the inner layers. The electrochemical measurements demonstrate that the HSCT-hollow-sphere-based electrode manifests a high specific capacitance of 1018 F g^-1 at 1 A g^-1 which is higher than those for hollow TiO₂ (113 F g^-1) and SiO₂/TiO₂ (252 F g^-1) electrodes, and substantially higher than those of all the previously reported TiO₂-based electrodes.