Boron-Induced Nitrogen Fixation in 3D Carbon Materials for Supercapacitors

Nitrogen-rich carbon materials attract great attentions because of admirable performance in energy storage and electrocatalysis. However, conductivity and nitrogen content are somehow contradictory because good conductivity requires high temperature heat treatment, which decomposes most of nitrogen species. Herein, we propose a facile method to solve this problem by introducing boron (B) to fix the nitrogen in a 3D carbon material even at 1000 ºC. Besides, this N-rich carbon has high ratio of pyrrolic nitrogen due to the selective stabilization of B, which is favorable in electrochemical reaction. Density functional theory (DFT) investigation demonstrates that B reduces the energy level of neighboring N species (especially pyrrolic nitrogen) in graphene layer, making it difficult to escape. Simultaneously, this carbon material achieves high conductivity (30 S cm-1) and nitrogen content (7.80 at.%), thus harvesting an outstanding capacitance of 412 F g-1 and great rate capability.