Optical Design and\nPreparation of WZr–SiZrO\nNanocermet-Based Solar Selective Absorbing Coatings for High-Temperature\nPhotothermal Conversion

The urgent need for next-generation concentrated solar\npower drives\nthe pursuit of highly efficient, thermally stable, and scalable solar\nselective absorbing coatings (SSACs). So far, the commercially available\nnanocermet-based SSACs (such as Mo–SiO<sub>2</sub>, Mo–Al<sub>2</sub>O<sub>3</sub>, and W–Al<sub>2</sub>O<sub>3</sub> coatings)\nsuffer from optical performance degradation due to structural collapse\nunder a high-temperature and weak oxidizing atmosphere. To address\nthis challenge, the SiZrO dielectric and WZr–SiZrO nanocermet\nare developed and employed to construct SSACs. In order to obtain\nexcellent optical performance [using the photothermal conversion efficiency\n(η) as the criterion], we first utilize theoretical simulations\nto determine the structural parameters of the target coatings. With\nthis guidance, the WZr–SiZrO nanocermet-based SSACs are experimentally\nprepared, demonstrating high solar absorptance (96.8%), low emittance\n(14.0%@500 °C), and incident light angle insensitivity (0–56°).\nBenefiting from the improved thermal stability and oxidation resistance\nof the component materials, the prepared SSACs have enhanced high-temperature\ndurability, maintaining η = 84.3% even after annealing at 650\n°C in 0.2 Pa for 635 h. These results suggest that the well-designed\nWZr–SiZrO nanocermet-based SSAC is promising for use in high-temperature\nphotothermal conversion.