Fluence-Dependent Changes in Surface Wettability and Conductivity of Ion-Irradiated Carbon-Based Foils

The surface properties and electrical behavior of carbon-based materials can be effectively tailored by energetic ion irradiation. In this study, graphene oxide (GO), cyclic olefin copolymer foils (COC, Topas 112 and 011, respectively) were irradiated with 1 MeV Au ions using a 3 MV Tandetron accelerator at fluences of 1 × 1014, 1 × 1015, and 2.5 × 1015 ions/cm2. The irradiation induced systematic modifications in surface chemistry, morphology, wettability, and electrical properties. Compositional changes before and after irradiation were investigated using Rutherford backscattering spectrometry (RBS) and elastic recoil detection analysis (ERDA), while surface morphology and roughness were characterized by atomic force microscopy (AFM), revealing a clear fluence-dependent evolution of nanoscale topography. The vibrational characteristics will be assessed through Raman spectroscopy. Surface wettability was evaluated by static contact angle measurements, and surface free energy was determined using the Owens–Wendt–Rabel–Kaelble (OWRK) method, showing a consistent decrease in water contact angle and an increase in surface free energy with increasing ion fluence in Topas 112/011 but not in GO. Electrical characterization demonstrated a pronounced fluence-dependent decrease in sheet resistivity across all investigated substrates. The results show that 1 MeV Au-ion irradiation enables controlled modification of both surface and electrical properties of carbon-based foils.