Phase change materials (PCMs) are promising in many fields related to energy utilization and thermal management. However, the low thermal conductivity and poor shape stability of PCMs restrict their direct thermal energy conversion and storage. The desired properties for PCMs are not only high thermal conductivity and excellent shape stability, but also high latent heat retention. In this study, the boron nitride nanosheets (BNNSs) were bridged by small amounts of GO nanosheets and successfully self-assembled into BNNS/rGO (BG) aerogels by hydrothermal and freeze-drying processes. The BG aerogels with interlaced macro-/micro-pores have been proven to be ideally suited as support frameworks for encapsulating polyethylene glycol (PEG). The obtained composite PCMs exhibit high thermal conductivity (up to 1.12 W m⁻¹ K⁻¹), excellent shape stability (maintain at 90 °C for 10 min), and high latent heat (187.2 J g⁻¹) with a retention of 97.3% of the pure PEG, presenting great potential applications in energy storage systems and thermal management of electronic devices.

The nucleation and growth of bubbles on homogeneous wetting surfaces have been extensively studied, but the intricate dynamics on hybrid wetting surfaces remain under-explored. This research aims to elucidate the impact of hybrid wettability on pool boiling heat transfer efficiency, specifically under downward-facing heating conditions. To this end, a series of hybrid wettability surfaces with varying hydrophilic and hydrophobic configurations are meticulously fabricated and analyzed. The study reveals distinctive interfacial phenomena occurring at the boundary between hydrophilic and hydrophobic regions during the boiling process. Experimental results indicate that surfaces with a higher proportion of hydrophilic to hydrophobic interfaces exhibit reduced superheat requirements and enhanced boiling heat transfer coefficients for equivalent heat flux densities. Furthermore, the rewetting characteristics of hybrid wettability surfaces are identified as pivotal factors in determining their critical heat flux (CHF). This investigation underscores the potential of hybrid wettability surfaces to optimize pool boiling heat transfer, offering valuable insights for the design and en-hancement of heat exchangers and other thermal management systems.