Hierarchical porous carbon nanoarchitectonics with honeycomb-like and N, P co-doped features for flexible symmetric supercapacitors and high-efficiency dye removal

In this study, we prepared a variety of hierarchical porous carbon (NPy-HPC) nanoarchitectonics with honeycomb-like and nitrogen-phosphorus co-doping features utilizing a combination of self-doping and external doping ways to maximally improve the properties of biomass-derived porous carbon. The as-obtained NP1.0-HPC possesses an appropriate heteroatom content (3.15 at.% for nitrogen and 0.3 at.% for phosphorous), high specific surface area of 2141 m2 g-1 and total pore volume of 1.04 cm3 g-1, making it a potentially bifunctional material for electrochemical energy storage and dye removal applications. The free-standing NP1.0-HPC electrode exhibits excellent electrochemical performance with a high specific capacitance of 378.8 F g-1 at 1 A g-1 and a good rate capability of 271.6 F g-1 when increasing the current density to 20 A g-1. The NP1.0-HPC//NP1.0-HPC symmetrical supercapacitor as well displays a desirable energy density of 17.7 Wh kg-1 at a power density of 440 W kg-1. Besides, NP1.0-HPC shows well removal capability for various kinds of dyes, among which the cationic dye methylene blue and the anionic dye methyl orange with the uptake of 666.9 and 360.9 mg g-1, respectively. Our work proposes a facile and cost-effective strategy for the exploration and development of superior performance controllable three-dimensional (3D) laminated porous carbon nanoarchitectonics.