Swift heavy ion irradiation of polyaniline-graphene nanocomposite films: Structural and optical properties

In this study, we investigate the use of swift heavy ions to modify the structural and optical properties of PANIgraphene nanocomposite (PANI-G NC) films. PANI-G NC films were synthesized on Indium Tin Oxide (ITO)coated glass by electrochemical polymerization of aniline in the presence of CVD-grown graphene. The films were then irradiated with 36 MeV Cu8+ ions at fluences between 5.4 x 1012 and 6.4 x 1013 ions/cm2. SEM results show that irradiation up to 1.6 x 1013 ions/cm2 leads to the formation of a porous interconnected network, with graphene nanoparticles adhering to the PANI matrix. Beyond this fluence, a dense and compact granular structure appears. Raman spectroscopy reveals enhanced Raman scattering of the polaronic lattice and the introduction of defects in graphene. At fluences exceeding 2.1 x 1013 ions/cm2, the obtained spectra reveal a distinctive broad envelope centered at the D and G positions of graphene, characteristic of nanocrystalline graphite. X-ray diffraction shows an increase in both crystallinity and crystallite size of the PANI-G NC film with increasing fluence, followed by a decrease beyond a critical ion fluence. Optical modifications were characterized by a red shift in the UV-Vis spectrum with increased fluence. The optical band gap shows a decreasing trend with ion dose, attributed to the formation of carbonaceous clusters along the latent tracks of energetic ions. In short, this study demonstrates that swift heavy ion irradiation could be an effective tool for enhancing the structural and optical properties of PANI-G NC films and tailoring them for specific applications.