Facile Synthesis of Ultrafine and Highly Dispersible MnO2 Nanoparticles for Energy Storage in Supercapacitors

Manganese dioxide (MnO2) has been extensively investigated as an electrode material for supercapacitors because of its high theoretical capacitance, great abundance, and low toxicity. To obtain satisfactory capacitance performance, in recent years, many efforts have been dedicated to the fabrication of MnO2 nanoparticles that offer a larger specific surface area and an escalated chemical activity. Beyond them, the ideal dispersibility of nanoparticles in a liquid medium is also of vital importance when processing those powdery materials into slurry ones for some particular uses, such as editable and ink-printing supercapacitor devices. In this study, the as-synthesized ultrafine MnO2 nanoparticles having excellent dispersibility in water can be prepared via a facile one-step hydrothermal route, with a uniform size in diameter of 200 nm exhibiting a large specific surface area of similar to 389.7 m(2) g(-1), and a high specific capacitance of 135.7 F g(-1) at 5 mV s(-1).