Controlling the morphology and property of carbon fiber/polyaniline composites for supercapacitor electrode materials by surface functionalization

The effect of surface functionalization of carbon materials on the morphology and performance of carbon/polymer composite materials for supercapacitor electrodes was investigated here. Three kinds of functionalized carbon fibers were prepared by the simple chemical modification of carbon fiber, named oxidated carbon fiber (OCF), amino-functionalized carbon fiber (AFCF) and aminated triazine functionalized carbon fiber (ATFCF). Then functionalized carbon fibers were used to fabricate nanostructural polyaniline/CFs composites (PANI/OCF, PANI/AFCF, PANI/ATFCF) by electrochemical in situ polymerization under pulse current. The chemical compositions and morphologies of these PANI/CFs composites were studied by FTIR, Raman spectra and SEM. It was found that PANI on OCF composites displayed a disordered nanofiber structure owing to the non-covalent connection between PANI with OCF. Conversely, PANI grew on the surface of AFCF and ATFCF in an ordered fashion due to chemically covalent connection, exhibiting nanowire arrays and petal-like nanosheets, respectively. It hints that the morphology of PANI/CFs composites can be effectively adjusted by molecular structural design of functional groups on the functionalized CF. The electrochemical properties of these PANI/CF composites were evaluated by an electrochemical workstation. In comparison with noncovalent PANI/OCF composites, the strong covalent interactions together with the ordered nanostructures of PANI/AFCF and PANI/ATFCF facilitated faster charge transfer, smaller internal resistance and better mechanical properties, resulting in improved electrochemical performance.