Probing Leidenfrost effect via contact electrification

Droplet dynamics and liquid-solid (L-S) interactions at elevated temperatures hold significant relevance across various industrial applications, particularly in materials design and aerospace. The Leidenfrost effect, which generates a vapor layer above a critical temperature and effectively prevents direct contact between the droplet and the heated substrate, has been extensively used in surface engineering and thermal protection. Nevertheless, the L-S interfacial properties and charge transfer at high temperatures, especially near the Leidenfrost point (LFP), have been largely neglected in past studies. This study integrated L-S contact electrification (CE) with the Leidenfrost effect, elucidating their intrinsic connection for the first time. Notably, the observation that transferred charge peaks near the LFP not only provided new theoretical insights into the temperature modulation of L-S interface properties but also presented a rapid, objective method for determining the LFP using CE as a probe. This approach holds the potential to enhance thermal management systems, improve heat dissipation in electronic devices, advance surface treatment and self-cleaning technologies, and optimize the efficiency of high-temperature self-powered equipment.