Cooperative regulation of hard template and emulsion self-assembly to the synthesis of N/O co-doped mesoporous hollow carbon nanospheres for supercapacitors

Abstract

Hollow carbon nanospheres have attracted more and more attention as supercapacitor materials due to their excellent electrical conductivity, high theoretical surface area, high accumulation and rapid ion transfer and diffusion. In this work, we employed the Stöber method to create silica as a template, and then applied self-assembly and dopamine polymerization on the surface of the template to form SiO2@TMB-F127-PDA micelles. Then the nitrogen-doped mesoporous hollow carbon nanospheres (N-MHCNs) were prepared by carbonization and etching on the formed carbon precursors. The effect of dopamine amount on the structure and properties of N-MHCNs was systematically studied. Microstructural characterization results reveal that the morphology of N-MHCNs can be changed from sheet to sphere, and the particle size of N-MHCNs can be 33.8–225.7 nm, the specific surface area is distributed in the range of 175.9–430.1 m2 g−1. Due to the N,O heteroatomic co-doping and Porous spherical structure (with a small particle size of 33 nm, and a large specific surface area of 430.1 m2 g−1), typical sample N-MHCNS-2 shows excellent electrochemical performance in supercapacitors. And it has the highest specific capacitance (241 F g−1) at 0.5 A g−1 current density, excellent rate performance (capacity retention rate of 79 % when current density increases from 0.5 to 10 A g−1) and good cycling ability (capacity retention rate of 90.4 % after 3000 cycles), indicating that it shows great potential in energy storage. This approach provides new opportunities for the controllable synthesis of hollow mesoporous nanospheres and it can be extended to other systems such as hollow metals, metal oxide nanomaterials and carbon-based hybrids.