CeO2-x quantum dots decorated nitrogen-doped hollow porous carbon for supercapacitors.

The pseudocapacitive properties of CeO2 are largely dependent on its surface Faradaic redox reaction kinetics; however, its electrochemical performance is still limited by the low utilization due to the inefficient diffusionfreeways and the limited active sites. Herein, we prepare a 0D/3D composite composed of oxygen-deficient CeO2 quantum dots (0D) anchored on a 3D hollow porous N-doped carbon framework (CeO2-x QD@PHC) via a facile template-confined strategy followed by a chemical co-precipitation. The refined QDs and hollow structure greatly shorten the ion diffusion paths and lower the internal strain during cycling. The integration of CeO2-x QDs with PHC structure endows enriched accessible active sites and enhances the electrical properties. As a result, the optimized CeO2-x QD@PHC exhibits an improved specific capacitance and good rate performance in comparison to those of the CeO2-x-free PHC. Moreover, a symmetric supercapacitor with CeO2-x QD@PHC as an electrode is constructed, delivering a high energy density of 3.874 Wh kg-1 at a power density of 149.98 W kg-1.