Controlled synthesis of carbon spheres via the modulation of the hydrophobic length of fatty aldehyde for supercapacitors

A hydrothermal method was employed to synthesize nitrogen-doped porous carbon spheres (NPCSs), with tetraethoxysilane as the silica source, a phenolic resin, formed by the reacting 3-aminophenol with amphiphilic aliphatic aldehydes, as a carbon source and the self-assembly of imidazole cationic surfactant (1-dodecyl-3-methylimidazolium bromide) as a soft template. The effect of the carbon chain length of the fatty aldehyde on the morphology, pore parameters and electrochemical properties of the synthesized carbon nanomaterials was systematically investigated. Notably, the pyrene probe test shows that aliphatic aldehydes with different hydrophobic chain lengths are solubilized to the fence layer of the surfactant, which may increase the distance between the hydrophilic head groups of the surfactant and lead to collapsing of carbon sphere surfaces. Nonetheless, the synthesized N-doped porous carbon spheres exhibit interconnected pore structures, high surface area (1032–1040 m 2 g −1 ), large pore volume (0.82–1.30 cm 3 g −1 ), large pore size (3.73–6.32 nm) and abundant N content (5.86–6.94 at%). Moreover, Electrochemical tests in 6 M KOH demonstrated impressive electrochemical performance, with specific capacitance as high as 181 F g −1 at 1 A g −1 and an excellent rate capacity of 96% retention after 5000 cycles at 10 A g −1 . • The alkyl chain length of aliphatic aldehydes can effectively control the structure of carbon nanospheres. • Aliphatic aldehydes are solubilized to the fence layer of the surfactant micelles. • The self-assembly of imidazole cationic surfactant ([C12mim]Br) acts as soft template. • The NPCSs exhibited superior capacitive performance (181 F g -1 at current density of 1 A g -1 ). • NPCSs were synthesized through hydrothermally carbonization and corrosion of hydrogen acid.