Ultrathin Hexagonal Boron Nitride Coatings for Enhanced Condensation Heat Transfer

Dropwise condensation on hydrophobic surfaces, compared to filmwise condensation on hydrophilic surfaces, is considered to be an effective means to enhance heat transfer. However, the development of technologies for promoting dropwise condensation using hydrophobic coatings has remained challenging due to the potential trade-off between enhanced hydrophobicity and increased thermal resistance associated with thicker coatings. In this study, we reported the realization of enhanced condensation heat transfer with ultrathin chemical vapor deposition of hexagonal boron nitride coatings, while maintaining robust dropwise condensation with over 120 h. Our experimental results demonstrate a 4.6-fold improvement in the heat transfer coefficient compared with filmwise condensation on bare substrates. These findings suggest that hexagonal boron nitride holds promise as a surface coating for promoting dropwise condensation of water vapor, potentially impacting various fields that rely on efficient heat transfer processes.