Open-air combustion synthesis of three-dimensional graphene for oil absorption and energy storage

Highlights: • A scalable combustion flame method is developed for synthesizing 3D graphene. • The 3D graphene consists of few-layer graphene sheets. • The 3D graphene shows the potential application in oil absorption. • The MnO₂/3D graphene exhibits an energy density of 23.8 Wh/kg at 7.5 kW/kg. - Abstract: There are promising applications for three-dimensional (3D) graphene in energy storage, catalysis, mechanical sensors, oil absorption, etc. To realize these practical applications, a scalable, cost-effective, and controllable synthesis technique for growing 3D graphene is highly desired. In this study, a combustion flame method was developed to synthesize high-quality 3D graphene within 1 min in open air, demonstrating the high efficiency, cost-effectiveness, and scalability of the method. Based on its 3D porous characteristics, the 3D graphene shows promise for applications in oil absorption and supercapacitors. It has an absorption capacity of 60 times its original weight for oil and organic solvents with a recyclability of 15 times. When the 3D graphene was electrodeposited with manganese dioxide (MnO₂), the as-formed 3D MnO₂/graphene hybrid electrodes demonstrated electrochemical performance comparable to other reported MnO₂-based supercapacitors with an energy density of 23.8 Wh/kg at a power density of 7.5 kW/kg.