A Nanorod With Near-Perfect Absorption for Efficient Utilization of Solar Thermal Energy

Solar thermal utilization faces a significant challenge, with efficient photothermal conversion being the primary issue. Although plasma nanofluid-based direct absorption solar collectors have shown potential in providing excellent sunlight capture capabilities, their narrow-band absorption limits their efficient photothermal conversion. This study proposes an alternative solution by introducing gold nanorods that achieve nearly perfect absorption across 300–1100 nm. The study demonstrates that the spectral absorption capacity of nanorods remains unaffected by their size and material at specific concentrations and depths. The analysis of the electromagnetic distribution at the resonance absorption peak reveals that the nanorods exhibit a “lightning rod” effect and surface plasmon resonance, leading to significant absorption. Additionally, the study investigates the effect of five common plasma nanomaterials on the nanorods’ optical absorption properties. The results show that titanium nitride-based nanorods exhibit broad-spectrum absorption and require only a small concentration and depth to achieve a 95% solar weighted absorption fraction. This research provides a valuable guide for the efficient photothermal conversion of plasma nanofluids, enhancing their potential for solar thermal systems.