Graphene nanofluids containing core-shell nanoparticles with plasmon resonance effect enhanced solar energy absorption

Nanofluids are a kind of important working fluid in volumetric solar collector. Here, we presented a novel strategy to enhance the solar absorption properties of graphene nanofluids utilizing the plasmon resonance of core-shell nanoparticles. The preparation, micrograph, optical properties and thermal conductivity of nanofluid have been investigated by considering the effect of volume fractions, nanoparticles selection and temperature. Results show that the graphene-embedded Sn@SiO2@Ag nanofluid exhibits a strong absorption band in the range of 250–300 nm and 380–600 nm. The solar absorption performance of graphene nanofluids is enhanced significantly by the plasmon resonance absorption and thermal conduction bridge of graphene-embedded Sn@SiO2@Ag core-shell nanoparticles. The solar absorptance performance of graphene nanofluids was enhanced 2.9 times by adding 0.4 g/L Sn@SiO2@Ag solutions. An enhancement in thermal conductivity of 11.3% was obtained at 20 °C and 16% enhancement at 50 °C for 0.3 g/L graphene-embedded Sn@SiO2@Ag nanofluids. It is concluded that the synergic effect of Sn@SiO2@Ag core-shell nanoparticles and graphene nanosheets increases both the solar absorption coefficient and thermal conductivity of the nanofluids.