Preparation and Photothermal Conversion Properties of ZnO and ZnO/Au Nanofluids.

Solar photothermal utilization is the important aspect of solar energy utilization, among which the optical characteristics of nanofluids play a decisive role in the efficiency of solar photothermal utilization. ZnO nanoparticles with different morphologies were prepared by hydrothermal method, and then Au was successfully reduced to ZnO nanoparticles by sodium borohydride reduction method to prepare ZnO/Au composite nanomaterials. The morphology, structure and composition of ZnO and ZnO/Au nanoparticles were characterized by SEM and XRD. The UV/VIS/NIR absorption spectra show that ZnO/Au nanofluids significantly improve the absorption in the visible light band. Through the photothermal conversion experiment, the photothermal conversion performance of flower like ZnO nanofluids is better than that of rod like ZnO nanofluids. Due to the plasmon effect of Au, the photothermal conversion performance of ZnO/Au nanofluids is enhanced. When the concentration is 1.0 mg/mL, the photo thermal conversion efficiency of rod like ZnO/10% Au nanofluids is 59%, which is 16% higher than that of pure heat transfer oil nanofluids. When the concentration is 0.5 mg/mL, the photo thermal conversion efficiency of flower like ZnO/10% Au nanofluids is 71%, which is 28% higher than that of pure heat transfer oil nanofluids. [ABSTRACT FROM AUTHOR]