Surface Reconstruction\nof La<sub>0.5</sub>Sr<sub>0.5</sub>CoO<sub>3‑δ</sub> Ceramic\ntoward High Solar Selectivity\nfor High-Temperature Air-Stable Solar–Thermal Conversion

As a key device for solar energy conversion, solar absorbers\nplay\na critical role in improving the operating temperature of concentrated\nsolar power (CSP) systems. However, solar absorbers with high spectral\nselectivity and good thermal stability at high temperatures in air\nare still scarce. This study presents a novel surface reconstruction\nstrategy to improve the spectral selectivity of La<sub>0.5</sub>Sr<sub>0.5</sub>CoO<sub>3‑δ</sub> (LSC5) for enhanced CSP application.\nThe strategy could efficiently enhance the solar absorptance due to\nthe existence of a high-absorption thin layer composed of nanoparticles\non the LSC5 surface. Meanwhile, the crystal facet with low emittance\non the LSC5 surface was exposed. Thus, the LSC5 that underwent surface\nreconstruction achieved a higher solar absorptance (∼0.75)\nand lower infrared emittance (∼0.19) compared to the original\nLSC5 (0.63/0.21), representing an improvement of nearly 32%. Additionally,\nthe surface reconstructed LSC5 demonstrated a lower infrared thermographic\ntemperature and a higher solar–thermal conversion equilibrium\ntemperature compared to those of LSC5 and SiC. Moreover, the reconstructed\nLSC5 could maintain stable performance up to 800 °C in air, which\nmight simplify the complexity of the CSP systems. The surface reconstruction\nstrategy provided a new method to optimize the spectral selectivity\nof high-temperature stable ceramics, contributing to advancements\nin solar energy conversion technologies.