SiO2 stabilizes electrochemically active nitrogen in few-layer carbon electrodes of extraordinary capacitance

Abstract

Pyrrolic and pyridinic N dopants can dramatically increase the electrochemical activities of carbon and conducting polymers. Although N-doped conducting polymers suffer from rapid degradation, their carbon counterpart of extraordinary capacitance has remarkable rate performance and cycling endurance thanks to carbon's excellent electrical conductivity. But high nitrogen content and high electrical conductivity are difficult to achieve in a high-surface-area carbon, because the high chemical vapor deposition (CVD) temperature required for obtaining high conductivity also destabilizes under-coordinated pyrrolic and pyridinic nitrogen and tends to lower the surface area. Here we resolve this dilemma by using SiO 2 as an effective N-fixation additive, which stabilizes the N-rich nano few-layer sp 2 -carbon construct in 1000 °C CVD. This enables a scalable sol-gel/CVD fabrication process for few-layer carbon electrodes of extraordinary capacitance (690 F g −1 ). The electrodes have excellent rate performance and can maintain 90% of their initial capacitance after 30,000 cycles, thus potentially suitable for practical applications. Electrochemically active pyrrolic and pyridinic nitrogen in few-layer carbon are stabilized by SiO 2 as an effective N-fixation additive. This strategy resolves the dilemma of both high nitrogen content and high electrical conductivity in a carbon material.