Enhanced heat retention and energy efficiency in photothermal membranes via sealed light-absorbing cavity engineering

Achieving materials with low solar reflectance and minimal thermal losses is crucial for efficient solar energy harvesting, but simultaneously attaining these properties is challenging. To address this, we introduce a novel approach by engineering EGaIn photothermal nanoparticles, featuring an EGaIn core as the photothermal layer, encapsulated within a precisely designed conjugated organic shell. The conjugated organic layer was synthesized through a combination of aminoundecanoic acid and tannic acid, utilizing Schiff base and Michael addition reactions. This combination effectively regulates the thickness of the oxide layer on the EGaIn surface, thereby preserving photothermal efficiency and enhancing the interaction between EGaIn and the polymer matrix. Our method involves a hole-making process that firmly adheres nanoparticles to porous material surfaces, creating a photothermal cavity structure. This design integrates photothermal material with an insulating architecture, enhancing solar energy absorption and reducing heat loss. In practical applications, the prepared porous membrane achieved a temperature increase of 15 °C above ambient conditions, generating an output voltage of 100 mV and an output current of 38.8 mA in photothermal power generation. By overcoming traditional limitations of solar energy materials, this research establishes a way for the design and application of materials that successfully balance high solar absorption with minimal thermal losses. The developed membrane could play a pivotal role in the next generation of sustainable and efficient solar energy harvesting technologies, paving the way for more reliable and scalable renewable energy solutions.