Hydrothermal synthesis and pseudocapacitance properties of α-MnO2 hollow spheres and hollow urchins

In this work, alpha-MnO2 hollow spheres and hollow urchins are synthesized via a simple hydrothermal process without using any template or organic surfactant. The effect of the reaction time on the microstructure and morphology of samples is observed systemically. Meanwhile, the forming mechanism of hollow-structured (alpha-MnO2 is carefully investigated by using field emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), and high-resolution transmission electron microscopy (HRTEM). The results of nitrogen adsorption-desorption experiments and electrochemical measurements show that the product obtained by hydrothermal reaction for 6 h has large specific surface area, uniform pore-size distribution, and excellent capacitance performance, which make it have a potential application as a supercapacitor electrode material.