Metallic nanoparticles (NPs) are considered as promising candidates for solar energy harvesting owing to their strong localized surface plasmon resonance (LSPR), which supports pronounced optical absorption in the visible to near-infrared (NIR) spectral range. However, the inherently narrow spectral bandwidth of conventional metallic particles poses a significant challenge for their effective integration into direct absorption solar collectors (DASCs). In this study, we introduce SiO \(_{2}\) @Pt core–shell nanoparticles as an advanced nanofluid platform, engineered to achieve broadband and enhanced optical absorption that aligns well with the AM 1.5 solar spectrum, thereby maximizing solar-to-thermal energy conversion efficiency. For evaluation, we employ 3-D computational modeling framework using Full-wave field analysis based on finite element method (FEM) to explore optical absorption properties to estimate solar energy efficiencies of plasmonic nanofluids. The albedo factor of the SiO \(_{2}\) @Pt nanomaterials is significantly reduced, resulting in enhanced optical efficiency due to minimized radiative losses. Our results show that solar-weighted absorption efficiency (A \(_{m}\) ) of SiO \(_{2}\) @Pt-based nanofluids is enhanced over 98% at very low volume fractions (1.0 \(\times \) 10 \(^{-5}\) ) and improved the performance of DASC. Furthermore, in our comparative analysis, the investigated SiO \(_{2}\) @Pt nanostructures demonstrate superior A \(_{m}\) value (>15%) relative to SiO \(_{2}\) @Au counterparts, indicating their enhanced suitability for solar energy harvesting applications. These findings indicate that adjusting the proper geometric parameter of SiO \(_{2}\) @Pt nanoparticles provides a novel approach to harvesting solar energy flux under optimal conditions.
