Experimental Study on Spectral Characteristic Regulation of Noble Metal Nanofluids

In the splitting photovoltaic/thermal hybrid system, splitting nanofluids with dynamic optical regulation abilities enables flexible thermal/electrical output. In the present work, the optical regulation ability of precious metal Ag nanofluids was investigated experimentally. Three types of nanoparticles, including Ag, Ag coated with SiO₂(Ag@SiO₂), and ITO nanoparticles were prepared. Six methods, meanwhile, were employed for regulating the optical characteristics of Ag nanofluids, which included temperature, concentration, type of base solution, CoSO₄, mixed nanofluids, and the core-shell structure. The results indicate that the wide-tuning of transmittance is achieved by concentration (52.2%-43.4%) of CoSO₄ (49.5% to 42.5%). It is possible to simultaneously regulate the absorption of the solar spectrum band based on the mixed nanofluid. The type of base solution and the core-shell structure enable a red shift in the absorption peak from 445 to 475 nm. On the other hand, temperature allows for fine-tuning of transmittance, demonstrating high stability of Ag/ethylene glycol. The study achieved controlled regulation of the spectral properties of Ag nanofluids within the solar spectrum region, laying the experimental foundation for their application.