Highly ordered mesostructured silica spheres as template for polyaniline nanofibres: synthesis, characterisation and their electrochemical properties

Ordered micrometre-sized silica spheres with uniform morphology and mesoporous structures were prepared by a temperature-induced and polyethylene glycol-assisted assembly method. The porous surface of the silica spheres was used for the chemical polymerisation of aniline, as well as a sacrificial template for synthesis of polyaniline (PANI) nanofibres. The morphologies of PANI nanostructures were characterised by scanning electron microscopy and transmission electron microscopy. Microstructural analysis and properties evaluation of the as-prepared products were characterised by X-ray diffraction, thermogravimetric analysis (TGA), Fourier-transform infrared spectroscopy and N-2 adsorption-desorption analysis. TGA results demonstrated that about 95% of the mesoporous material has been utilised for the synthesis of PANI nanofibres. Their electron transfer properties were investigated by cyclic voltammetry (CV) and electrochemical impedance spectroscopy. CV experiment shows that the obtained PANI nanofibres have good electrochemical activity, which can be attributed to a higher number of accessible redox sites available during the synthesis process. The value of time constant (G) of PANI nanofibres based electrode was 0.0217 ms. The lower G-value is usually preferred for electrochemical capacitor for fast charge-discharge processes; hence, these PANI nanofibres based materials and their composites have the potential to be used as supercapacitor electrodes for supercapacitor applications.