Interface Electronic-Structure Engineered TiN/C Aerogel Composites for Latent Heat Enhancement in Water-Based Phase Change Materials toward Efficient Cold Energy Storage

To address the low thermal conductivity, severe supercooling, and poor long-term cycling stability of water-based phase change materials (PCMs), functional additives are commonly introduced. However, latent heat loss is inevitably induced by the disruption of the hydrogen-bonding network of water molecules. Herein, we propose an interface electronic-structure engineering strategy to regulate phase transition behavior by constructing electronically active heterointerfaces with a stable built-in electric field. The TiN/C heterostructure derived from MXene/cellulose aerogels is designed, in which TiN nanocrystals are in situ anchored within a porous carbon framework, forming robust TiN–C covalent interfaces. The resulting built-in electric field enhances water molecule polarization and interfacial chemical adsorption, stabilizes the hydrogen-bond network during repeated phase transitions, and promotes molecular and ionic migration. The optimized TiN/C-3 PCM exhibits a latent heat of 268.83 J g -1 with an ultralow additive loading of 7.1wt%, corresponding to a latent heat retention of 97.92%, and maintains 97.7% of its initial performance after 100 cycles. Cold-chain simulations further demonstrate stable temperature control at 0–4 °C for over 7 h, highlighting its potential for sustainable cold-chain applications. This work provides an effective strategy for designing high-performance PCMs, demonstrating the enormous potential of sustainable cold chain logistics.