Hierarchically Porous Mesostructured Polydopamine Nanospheres and Derived Carbon for Supercapacitors

Polydopamine (PDA), with similar chemical and physical properties to eumelanin, is a typical artificial melanin material. With various functional groups, good biocompatibility, and photothermal conversion ability, PDA attracts great interest and is extensively studied. Endowing PDA with a porous structure would increase its specific surface area, therefore would significantly improve its performance in different application fields. However, creating abundant pores within the PDA matrix is a great challenge. Herein, a self-assembly/etching method is proposed to prepare hierarchically porous mesostructured PDA nanospheres. The oxidative polymerization of dopamine and hydrolysis of tetraethyl orthosilicate were coupled to co-assemble with a polyelectrolyte & minus;surfactant complex template to form a mesostructured PDA/silicate nanocomposite. After removing templates and etching of silica, hierarchically porous PDA nanospheres were obtained with specific surface area and pore volume as high as 302 m2 g & minus;1 and 0.67 cm3 g & minus;1, respectively. Moreover, via subsequent carbonization and silica-etching, ordered mesoporous N-doped carbon microspheres (OMCMs) with similar to 2 nm ordered mesopores and similar to 20 nm secondary nanopores could be obtained. When used as electrodes of supercapacitors, the OMCMs exhibited a specific capacity of 341 F g & minus;1 at 1 A g & minus;1 with excellent rate capability, and the OMCM-based symmetric supercapacitor delivered a high energy density of 14.1 W h kg & minus;1 at a power density of 250 W kg & minus;1 and minor capacitance fading (only 2.6%) after 10,000 cycles at 2 A g & minus;1.

Automated summary

Polydopamine (PDA), an artificial melanin material with similar properties to eumelanin, has attracted great interest due to its various functional groups, good biocompatibility, and photothermal conversion ability. This study proposes a self-assembly/etching method to prepare porous mesostructured PDA nanospheres, which exhibit high specific surface area and pore volume. The study also demonstrates the potential of using ordered mesoporous N-doped carbon microspheres (OMCMs) obtained from PDA as high-performance electrodes for supercapacitors.