Graphene Oxide−Silica Microcapsules Containing Phase Change Materials for Thermal Energy Storage

Phase change materials (PCMs) utilize reversible phase transitions (e.g., solid−liquid) to store large quantities of heat. However, many organic PCMs suffer from low thermal conductivity and leakage problems during the solid−liquid phase transition that can be addressed using microencapsulation. In this work, we developed a scalable, surfactant-free Pickering emulsion templating method to microencapsulate paraffin wax within silica−graphene oxide shells. Graphene oxide serves dual functions as both an emulsion stabilizer and interfacial catalyst for silica formation via sol−gel chemistry. We achieved 94% encapsulation efficiency and excellent thermal stability demonstrated over 500 melt–crystallization cycles. The obtained PCM is inherently flowable, demonstrating a 34% increase in heat transfer coefficient relative to water, and directly mitigates paraffin’s intrinsic thermal conductivity limitation.