Outstanding photothermal performance of metal-like CeO₂–Co₃O₄ and excellent photothermal storage of Ca(OH)₂–CeO₂–Co₃O₄

Thermal energy storage technology is an effective means for expanding the use of solar energy. Light harvesting across the full solar wavelength is essential for ensuring photothermal efficiency. Lattice defect engineering has been widely used to narrow the band gap and induce surface plasmon resonance absorption. In this study, we present an alternate method for intensifying light absorption. The CeO₂–Co₃O₄ redox system possesses highly delocalised electrons and numerous oxygen vacancies, allowing considerable light harvesting over the full solar spectrum. By incorporating CeO₂–Co₃O₄ as an absorber, the photothermal temperature, photothermal dehydration conversion and reversibility of the thermal storage and release cycles of Ca(OH)₂ can be drastically enhanced. The dehydration kinetics of Ca(OH)₂ are also substantially increased by reducing the dehydration activation energy using CeO₂–Co₃O₄. The Ca(OH)₂–CeO₂–Co₃O₄ composite is a promising candidate for one-step photothermal conversion and thermal energy storage. Herein, we develop a light–material design for the very first time using a redox system.