Light-Induced Optical and Interfacial Charge Modulation in SiC/PS Nanocomposites for Photocatalytic Applications

Silicon carbide/polystyrene (SiC/PS) nanocomposites with 1–10 wt% SiC were synthesized to investigate how structural, optical, and interfacial properties govern light-induced behavior relevant to photocatalysis and photochemical processes. SEM and XRD measurements confirmed that micron-scale, highly crystalline β-SiC is successfully incorporated into the amorphous PS matrix, with progressively intensified SiC reflections as loading increases. Williamson–Hall analysis showed that the 7 wt% composite exhibits the largest crystallite size (≈30.23 nm) and minimal microstrain, suggesting reduced lattice distortion and more efficient pathways for charge separation at polymer–ceramic interfaces. UV–Vis spectroscopy demonstrated that SiC concentrations of 1–5 wt% sharpen the absorption edge and increase the direct band gap from 3.91 to 4.22 eV and the indirect band gap from 2.91 to 3.82 eV. This band-edge modulation indicates suppression of defect-assisted transitions and improved generation of photo-excited carriers under UV illumination—properties essential for photocatalytic activity. At higher loadings (≥7 wt%), strong absorption and scattering prevent reliable gap extraction, pointing to intense photon attenuation within the composite. FTIR analysis revealed preserved PS vibrational signatures together with progressively strengthened SiC-related modes (Si–O–C at 1100–1150 cm⁻¹, Si–C/Si–C–O at 800–600 cm⁻¹, and a ~910 cm⁻¹ surface phonon), confirming physical rather than covalent interactions and indicating increased exposure of optically active SiC surface sites. Dielectric spectroscopy showed a systematic rise in ε′ and ε″ with increasing filler concentration due to Maxwell–Wagner–Sillars interfacial polarization, highlighting enhanced charge accumulation and migration under alternating fields. These results establish a direct correlation between SiC loading, photon absorption behavior, and interface-driven charge dynamics, identifying 3–5 wt% as optimal for UV-activated photochemical applications and 7 wt% as the most structurally stable composition.