Solar absorption characteristics of SiO₂@Au core-shell composite nanorods for the direct absorption solar collector

It has been reported that plasma nanofluids are beneficial to improve the performance of a direct absorption solar collector (DASC). For this purpose, the solar absorption of gold sphere nanoparticles (NPs) in the near-infrared spectral region and gold nanorods in the visible spectral region needs to be focused. Based on this issue, we propose a core-shell composite nanorod and investigate its optical properties to illustrate its potential for improving the solar absorption efficiency of the DASC. The results show that the core-shell composite nanorod improves the absorption efficiency both in the near-infrared and visible spectral region. Further study reveals that the absorption mechanism of the composite nanorods can be attributed to localized surface plasmon resonance (LSPR) and propagating surface plasmon resonance (PSPR). In addition, in view of the discussion about the geometrical size of composite nanorods and the calculation of composite nanorod suspension, the solar absorption efficiency can be as high as 95.3%. Notably, the imperfect shell during the experimental synthesis will greatly reduce the absorption capacity of the composite nanorods. The results show that the core-shell composite nanorod has great potential in the DASC applications.