Facile synthesis of porous biocarbon decorated with MnO-CeO2 nanocrystals for high-capacitance electrodes

The increasing demand for power storage device with high energy density forces the scientists to design new materials as electrodes. In this work, hollyhock stalks were converted into porous carbon host for growth of MnO and CeO 2 nanocrystals hydrothermally. The obtained biocarbon with macro-meso-micro porous structure provides excellent electron transport properties, while the nano-size MnO-CeO2 (<10 nm) on it grants high capacitance. Due to the unique nanostructure of carbon skeleton and ultra-large surface areas (514.4 m 2  g −1 ), the MnO-CeO 2 nanocrystals/porous carbon displays excellent electrochemical capacitance performance (162 F·g −1 at 0.5 A·g −1 ) and cycle stability. The specific capacity remains 99.3% efficiency after 1000 cycles at 500 mA·g −1 .