Hydrothermally synthesized cobalt oxide/polydimethylsiloxane based photothermal absorber for superior thermal energy conversion and water evaporation application

Solar-driven interfacial evaporation has garnered worldwide interest in recent years due to its unique vapor generating capacity using sustainable solar energy. Many photoabsorber have been studied for conversion of photothermal energy and heat absorption. Unfortunately, the majority of the absorber materials in supply are pricey, and the installation procedures tend to be intricate. This research focuses on the ongoing difficulty of creating cost-efficient photothermal materials that have excellent light absorption and simple manufacturing processes. We created a novel composites coated with Cobalt oxide and polydimethylsiloxane (Co₃O₄/PDMS) which successfully produce energy and purify water utilizing an extensive spectrum of solar energy. Hydrothermally synthesized Co₃O₄ particles exhibit distinct optical properties in the UV–Vis region due to ligand field transitions and charge transfer between Co²⁺ and Co³⁺ ions. Additionally, these particles exhibits a strong absorption in the NIR region due to the intervalence charge transfer and d-d transitions, enhancing their photothermal activity. This culminates in outstanding light-to-heat transformation in the Co₃O₄/PDMS composite, which maintains a surface temperature of 42.7 °C compared to 33.7 °C for pristine PDMS under standard 1 sun intensity for 5 min. The flexible Co₃O₄/PDMS composite transfers solar energy to electric energy, producing ∼99 mV with 1 sun irradiation, while bare PDMS only achieved a voltage of 61 mV under 1 sun circumstances. An efficient double layer Co₃O₄/PDMS@MF sponge achieved an evaporation rate of 1.33 kg m⁻² h⁻¹ with the photothermal conversion efficiency of 68.8 %. These results motivate thorough investigation in photothermal potential of Co₃O_4, revealing the promising possibilities for harnessing solar-thermal energy and presents a novel method for using solar power to purify water and generate electricity.