Multifunctional organohydrogel with rambutan-like microstructure for waste heat recovery and intelligent sensing

Abstract

Energy shortages and ecological concerns have led to a focus on efficient waste heat utilization. Phase-change organohydrogels and thermoelectric generators combine to provide electricity from waste heat, which is a promising method for waste heat recovery and reuse. In this work, a multifunctional organohydrogel was elaborately fabricated through the Pickering emulsion method and UV-initiated polymerization, composed of rambutan-like phase change microspheres and polyacrylamide (PAAm) skeleton. In particular, the paraffin wax (PW) was employed as a phase change material and microencapsulated within cellulose nanofibril (CNF)/carbon nanotube (CNT)/Fe3O4 hybrid shells. Attributed to the unique microspheres, the resultant organohydrogel possessed various advanced features. The phase transition behaviors of the microspheres enabled the organohydrogel to store, release, and manage thermal energy. Harvested waste heat can be efficiently stored in the organohydrogel and discharged into the thermoelectric system. The thermoelectric generator achieved remarkable output voltage and current of 518.0 mV and 86.3 mA via thermal-electricity conversion, respectively. Additionally, the organohydrogel also exhibited favorable thermosensitive properties over a wide temperature range (from −18.0 to 90.0 °C), and mechanical responsiveness with a low detection limit (1.0%). Thus, organohydrogels with rambutan-like microstructures presented promising potentials for thermal energy storage systems and next-generation multifunctional electronic devices.