Simple synthesis of uniform carbon flower superstructures for electrocatalysts and other energy and environment applications

Engineers in Professor Zhenan Bao's laboratory have developed a simple, low-cost, tunable, one-step polymerization process followed by pyrolysis for producing uniform carbon particles with a variety of different superstructures (flower, petals, pompom shapes around 1um). Three-dimensional hierarchical porous carbon materials with flower-like superstructures provide highly accessible surface area and facilitate ion transport for high-rate capability which is valuable for energy applications. However, traditional synthesis of these geometries has been difficult and produced low quality materials that do not have regular, predictable structures. This new tunable process solves that problem using a one-pot, free-radical polymerization and self-assembly process that controls structure and porosity through solvents and co-monomers. The resulting carbon particles have uniform structure and desirable electrical properties. This method opens the possibility to synthesize carbon materials in a simple and controlled way with unique morphology, high surface area and tunable heteroatom content for future applications in electrochemical energy conversion and storage, such as supercapacitors, electrocatalysts and lithium-sulfur batteries, waste water treatment and gas storage.

Synthesis of carbon flower superstructures: This schematic image shows the variety of structures formed by varying the solvents for this simple polymerization process. Additional shapes and pores can be introduced by incorporating other co-monomers.

Stage of Research
The inventors have synthesized 50 g of uniform polyacrylonitrile materials that were readily converted to carbon particles with tunable porosity via gas treatment methods (this can be easily scaled up for industrial purpose). The resulting carbons had diameters around 750 nm, exhibited high N-doping concentration (7-15 at%) and good performance as electrocatalysts. In addition, the inventors were able to accurately determine solvents for preparing particles with desired shapes by using Hansen solubility parameters.