Fast joule-heating synthesized heteroatom-doped carbon and its impressive electrochemical performance

To tackle the issues of slow heating/cooling process and underutilization of heat in the traditional electric furnace pyrolysis, a fast Joule-heating pyrolysis is herein reported. The Joule heat generated by applying DC voltage to the left and right flanks of the electrically conductive precursor, viz. carbon fiber cloth supported polyaniline, can turn the precursor into N, S-codoped carbon material within minutes. When the pyrolysis voltage locates between 1.0–6.0 V and lasts for 10 min, the surface temperature field of the precursor resembles quasi-concentric circles, with the highest temperature in the core and gradually decreasing temperature around. A fairly high core temperature close to 600 °C can be achieved by applying a DC voltage of 6.0 V for merely ∼150 s. Only by reaching 4.0 V upwards can the polyaniline be ruptured and then converted to more stable CN and CS groups. The pyrolyzed products of polyaniline present as thin coatings with uniformly distributed C, N, S, O elements on the heat-resistant carbon fiber cloth support. In accordance with comparative studies on the carbon-based electrode derived from traditional electric furnace pyrolysis, fast Joule-heating pyrolysis is found to be a wiser strategy to prepare heteroatom-doped carbon materials with impressive capacitive and electrocatalytic performance.