One‐Pot Synthesis of Uniformly Dispersed Carbon Nanospheres Using High Concentration Glucose Adjusted by Cationic Surfactants

Carbon nanospheres (CNSs) are synthesized through the direct hydrothermal method by using the polyelectrolyte polydiallyldimethylammonium chloride (PDDA) as a cationic surfactant and high concentration glucose as a carbon source. The produced samples are systematically characterized by scanning electron microscope, transmission electron microscope, X‐ray photoelectron spectroscopy, zeta potential analysis, X‐ray diffraction, and Brunner–Emmet–Teller measurements. The obtained CNSs are well dispersed with particle size ranging from 70 to 100 nm. Their specific surface area increases remarkably to 1597 m 2 g −1 after activated by potassium hydroxide, together with the formation of hierarchical micropores and mesoporous structures (an average pore size of ≈3 nm). The possible reaction mechanism of the CNSs is deduced on the basis of the above characterizations, and the size of the CNSs can be regulated by the PDDA with different molecular weight. The CNSs material exhibits a specific capacitance of 121.1 F g −1 when used as a supercapacitor electrode at a current density of 0.5 A g −1 . Remarkably, the CNSs electrode shows excellent rate capability and outstanding cycling stability with almost no degradation over 7,000 cycles. These data reflect their excellent electrochemical performance for supercapacitor.