A Directional Synthesis for Topological Defect in Carbon

Metal-free carbon catalysts, especially with rich topological defects, have exhibited extraordinary performance in various electrochemical reactions. To fundamentally understand the relation of activity with specific defect, control of defect type in carbon is indispensable and unfortunately still remains a great challenge to date. Here, we developed a general edge-engineering method to produce a class of definitive defect configurations converted from corresponding specific nitrogen (N) doping sites. Theoretical simulations provide the fundamental capability and the design principles. Experimentally, structural characterizations clearly elucidate the specific one-to-one conversion of confirmative N configuration to carbon defect; e.g., graphitic-N to divacancy (C585), pyridinic-N to separate pentagon (S-C5), and pyrrolic-N to adjacent pentagons (A-C5), respectively. For electrocatalysis, A-C5 defects show the highest intrinsic activity in oxygen reduction reaction, whereas C585 defects perform the best in hydrogen evolution reaction. This work provides the main guidance in design of carbon-based catalysts via control of target defect synthesis.