The wetting and bonding behaviors between electrode nano-metals and carbon materials play an important role in dissimilar joining and solidification especially for graphene/carbon nanotube (CNT) based nano-devices. As an important indicator, the contact angle between them can provide explicit information for the understanding of their interfacial interactions. However, the conventional sessile drop method is still limited to the macroscale, and whether the wettabilities of materials at nanoscale will still follow the rules established based on their bulk counterparts remains unknown. In this paper, we show an in situ approach to investigate the sublimation and wetting behaviors of Ag nanocrystals on graphene/CNTs at elevated temperatures through a high-resolution transmission electron microscope. It is found that, i) Ag nanocrystals soften and sublimate at a lower temperature and possess a higher sublimation speed than theoretical predictions, ii) the intrinsic contact angle between Ag nanocrystals and graphene/CNTs at elevated temperatures mainly maintains a mean value of around 124°–125°, and iii) the contact angle decreases with the decrease of nanoparticle size when it is below 15 nm.
Authors investigated the sublimation and wetting behaviors of Ag nanocrystals on graphene/CNTs with in situ heating HRTEM. The observed faster sublimating at lower temperatures than theoretical predictions. The wetting angle was quantified as a function of particle size.