Improved absorption of phosphates through interface junctions and photothermal–energy–storage capability of Ca(OH)₂–[Co₃O₄–Co₃(PO₄)₂]

Strong absorption in the full solar spectrum is required for efficient usage of solar energy. Near-infrared (NIR) light absorption mainly depends on surface plasmon resonance and a high density of free charge carriers (FCCs). However, increasing FCC density in semiconductors is still a challenge. In this work, we demonstrated that multitudinous S-scheme interface junctions can be constructed within nanoscale Co₃O₄–Co₃(PO₄)₂, leading to enhanced light absorption of phosphates over the entire solar spectrum due to the increased FCC density and charge-carrier configurations. This absorber can also boost the photothermal performance of Ca(OH)₂. The photothermal dehydration conversion of Ca(OH)₂ is considerably improved (13.7 times). The reversibility of the photothermal hydration–dehydration cycles of Ca(OH)₂ is improved by 39 times. This composite is promising for photothermal conversion and thermal energy storage in one-step.