3D printing of phase change material-based Pickering emulsion gel for solar-thermal-electric conversion

The rapid global increase in the consumption of fossil energy had led to urgent environmental issues, thereby prompting vigorous efforts towards the development and application of renewable energy. The effective encapsulation of phase change materials (PCMs) is crucial and indispensable for achieving high-performance solar-thermal energy harvesting and storage. However, challenges persist in the manufacturing of PCMs encapsulations with customizable and intricate structures to meet diverse scenarios. Herein, a PCMs Pickering emulsion gel ink, based on lignocellulosic nanofibers (LCNFs)/graphene oxide (GO) nanosheets stabilized paraffin, has been prepared to fabricate customized PCMs using 3D printing techniques for solar-thermal-electric conversion applications. The micro-nano matrix consisting of LCNFs and GO nanosheets provides a stable oil/ water (O/W) interface, limits movements and deformability of paraffin microsphere, thereby increasing the viscosity and stiffness of the PCMs Pickering emulsion gel ink to ensure its excellent rheological property. Moreover, the LCNFs enhance printability and shape fidelity of the ink as interfacial stabilizer and viscosity modifier, which facilitates the manufacture of various 3D geometries. As a result, the designed concave PCMs solar harvester not only exhibits exceptional solar-to-thermal conversion efficiency, but also effectively mitigates heat loss and enables efficient heat storage for electricity generation. Our work demonstrates a new way toward utilization of LCNFs as PCMs emulsion stabilizers and encapsulants in PCMs and the fabrication customized PCMs architectures for solar-thermal-electric conversion applications using 3D printing techniques.