Wetting dynamics of nanoliter water droplets in nanoporous media

Scalable nanoporous carbon films allow line-of-sight 3D atomic layer deposition of Pt: towards a new generation catalyst layer for PEM fuel cells

“…As explained in our recent work, [8][9][10] the NCS is fabricated by a combination of sonication and low energy ball-milling of mixtures of mesophase pitch (MP)/n-butanol (BtOH), polyvinyl alcohol (PVA)/water and silica nanoparticles/1,3-propanediol (PD)/water (Fig. 1 and Fig.…”

“…The hydrophilicity of the NCS arises from the high coverage of surface oxygen groups, originating from its imprinting with silica colloids and potentially also from the last step of NCS fabrication when the silica NPs are removed by treatment in base. 10 For these reasons, the NCS surface characteristics were expected at the outset to be uniquely beneficial for the tethering of the Pt precursor during ALD, subsequent Pt NP nucleation and growth, and for stabilization of the NPs during their operation as an ORR catalyst.…”

“…In one of these studies, 9 the internal surface NCS85 was modified to control its wettability, revealing that a combination of small hydrophobic pores and larger hydrophilic cracks facilitate oxygen and water transport, respectively. In our other work, 10 NCS22 and NCS85 were used as a model of an ideal nanoporous material to study the dynamics of nanoliter droplet imbibition and capillary rise for application in natural porous media, e.g., shale rocks. To further expand the applications of these NCS materials, we have become interested in depositing a second or even third phase into their internal structure, starting with electrocatalytic metallic nanoparticles (NPs), especially for the oxygen reduction reaction (ORR), one of the major bottlenecks of PEM fuel cells.…”

Droplet Nucleation and Growth in the Presence of Noncondensable Gas: A Molecular Dynamics Study

“…Furthermore, based on the classical nucleation theory, the corners inside the nanostructures are more suitable for nucleation. In addition to the geometry effect, the spontaneous inbibition of a droplet into hydrophobic pores (Lucas–Washburn equation − ) could also be a factor leading to the inside nucleation and growth. At the initial stage of dropwise condensation, the random nucleation is also assumed to occur on the top of rough structures and the spontaneous inbibition of the cluster will also lead to an inside restart.…”

Effect of surface micromorphology and hydrophobicity on condensation efficiency of droplets using the lattice Boltzmann method

“…Recently, researchers have carried numerous experiments about the influence of droplet condensation on the heat transfer and dynamic characteristics of the droplet condensation, mainly focusing on the effects of surface wettability [4,5], surface morphology [6,7] and subcooling [8,9]. Xie et al [10] carried out dropwise condensation experiments on different surfaces and found that the wettability of superhydrophobic surfaces decreases as the temperature increases, while the smooth hydrophobic surfaces could maintain stable heat transfer.…”