Multifunctional nitrogen-rich “brick-and-mortar” carbon as high performance supercapacitor electrodes and oxygen reduction electrocatalysts

Abstract

Novel porous carbon materials with excellent electronic, chemical and structural properties and high nitrogen content are desirable for many applications. Here, we show the design and synthesis of a new multifunctional porous carbon material with a unique architecture through a simple but effective activation-free procedure. Porous carbon derived from a copolymer poly(vinylidene chloride-co-acrylonitrile) serves as the nitrogen-rich “mortar”. Reduced graphene oxide layers work as “bricks” with an aim to provide an open nanoscale scaffold and connect porous carbon, as well as modulate the ratio between mesopores and micropores. This new material has a large surface area (957 m² g⁻¹), high nitrogen content (6.6 at%), excellent conductivity (up to 5.1 S cm⁻¹), and favorable hierarchical meso- and microporosity. Benefiting from these intriguing features, this material shows an ultrahigh specific capacitance of 361 F g⁻¹ in an aqueous electrolyte. The as-assembled asymmetric supercapacitors with the designed carbon materials as negative electrodes and porous cobalt oxide nanorods as positive electrodes deliver a high-energy of 50.1 W h kg⁻¹ with a cell voltage of up to 1.6 V. Further, this material shows high electrocatalytic activity for the oxygen reduction reaction in alkaline medium comparable with that of 20 wt% platinum–carbon electrodes, with better methanol tolerance and long-term durability. We expect that this uniquely designed nitrogen-rich porous carbon material with its simple and scalable synthesis method will have great potential for various applications in energy storage, energy conversion and catalysis.