No abstract

Nitrogen-doped hollow carbon spheres (HCSs) are regarded as ideal supercapacitors electrode materials due to their excellent electrochemical properties. However, studies of nitrogen doping at different levels based on precise structure control are rarely reported so far. Herein, we controllably prepared hollow carbon nanospheres with carbon walls connected by a hard template method and used the difference in the number of nitrogen-containing functional groups in the precursor to control the nitrogen doping amount of carbon nanospheres. Interestingly, with the N-doped content increasing, the specific capacitance of supercapacitors shows accordingly upward tendency by the better electrode interface environment. Compared to the control group (lower amount nitrogendoping), the highest N-contained HCSs (NIHCSs-2) shows the best electrochemical performance (256 F g À 1 ) in supercapacitors. The excellent electrochemical behaviour of NIHCSs-2 demonstrates that hollow carbon nanospheres with high nitrogen content have great potential in electrochemical energy storage device applications.