Exceptionally boosted absorption of silicates by interfacial junctions and direct light–heat–energy storage using Mg(OH)₂–(Co₂SiO₄–Co₃O₄)

Near-infrared (NIR) light absorption is essential for the effective utilization of photothermal solar energy, which is realized via the surface plasmon resonance of a high density of free charge carriers (FCCs). Herein, we demonstrate that S-scheme interfacial junctions (IJs) can substantially increase the FCC density and intensify absorption of silicates from the ultraviolet to NIR region. Numerous p–n IJs with S-scheme types are constructed within sheet-like Co₃O₄–Co₂SiO₄ nanoparticles, exceptionally boosting the light absorption capability over the entire solar spectrum. Moreover, this absorber can improve the photothermal performance of Mg(OH)₂ via a mixture of Mg(OH)₂–(Co₃O₄–Co₂SiO₄) composite. The photothermal dehydration conversion of Mg(OH)₂ in this mixture considerably improves by 6.7 times under 30-min irradiation. The reversibility of the photothermal hydration–dehydration cycles of Mg(OH)₂ improves by 18.3 times, and the thermal storage kinetics substantially improves via the reduction of the activation energy of dehydration (reduction of 25.4 %). Results indicate that Mg(OH)₂–Co₃O₄–Co₂SiO₄ is a promising candidate for a one-step system of photothermal conversion and energy storage.