Surface engineered ZnO and functionalized nanodiamond epoxy composites for enhanced mechanical, photocatalysis, and SERS applications

Zinc oxide nanoparticles (ZnO NPs) and nanodiamonds (NDs) have become well-known as high-performance additives to improve polymer composites. This research focuses on understanding the synergetic effects of ZnO NPs and FNDs inside an epoxy matrix and assessing their effects on mechanical, thermal, photocatalytic and Surface-Enhanced Raman Scattering (SERS) characteristics. The use of ZnO and FNDs significantly enhanced the nanoparticle dispersion and interfacial bonding, which led to significant improvements in properties. The 3 % epoxy/ZnO+FND composite showed outstanding mechanical properties with compressive strength of 98.7 MPa, flexural strength of 76.3 MPa, fracture toughness of 0.98 MPa·m^1/2, and elongation at break of 47 %. Thermal analysis showed a significant rise in the glass transition temperature (Tg ≈ 98 °C) and thermal conductivity (0.76 W/m.K). SEM, FTIR and XRD were used to confirm the successful synthesis of the NPs and integration with the surface modification effects. Photocatalytic study showed that the composites with higher NPs concentrations showed good degradation of methyl orange (MO) dye under UV irradiation. The SERS activity of epoxy/ZnO+FND substrates was determined using Rhodamine 6 G (R6G), malachite green (MG), and adenosine, resulting in high stability and a low detection limit of about 10⁻¹² M. The nanostructures also showed self-cleaning capability due to the visible cycles without significant performance loss. The results suggest the hybrid epoxy/ZnO+FND composites can be used as a strong bifunctional system that provides high-performance photocatalysis combined with high sensitivity of SERS detection. Such performance shows their potential for high-end applications in sensing and environmental remediation techniques. photocatalytic degradation of R6G, MG and adenosine by LED, enabling multiple reusability.