Abstract We experimentally realized and elucidated kinetically limited evaporation where the molecular gas dynamics close to liquid–vapour interface dominates overall transport. This process fundamentally dictates performance of various evaporative systems has received significant theoretical interest. However, experimental studies have been due difficulty isolating interfacial thermal resistance. Here, we overcome this challenge using an ultrathin nanoporous membrane in a pure vapour...

The green hydrogen economy is expected to play a crucial role in carbon neutrality, but industrial-scale water electrolysis requires improvements efficiency, operation costs, and capital costs before broad deployment. Electrolysis operates at high current density involves the substantial formation of gaseous products from electrode surfaces electrolyte, which may lead additional resistance resulting loss efficiency. A detailed clarification bubble departure phenomena against surface...

Evaporation is a ubiquitous phenomenon found in nature and widely used industry. Yet fundamental understanding of interfacial transport during evaporation remains limited to date owing the difficulty characterizing heat mass transfer at interface, especially high fluxes (>100 W/cm2). In this work, we elucidated into an air ambient with ultrathin (≈200 nm thick) nanoporous (≈130 pore diameter) membrane. With our evaporator design, accurately monitored temperature liquid-vapor reduced...

Water is often considered as the highest performance working fluid for liquid-vapor phase change due to its high thermal conductivity and large enthalpy of vaporization. However, a wide range industrial systems require using low surface tension liquids where heat transfer enhancement has proved challenging boiling evaporation. Here, we enable new paradigm transfer, which favors volatility, rather than water. We utilized nanoporous membrane ≈600 nm thickness <140 pore diameters supported on...

We derive the equation of motion for non-Markovian dissipative particle dynamics (NMDPD) by introducing history effects on time evolution system. Our formulation is based generalized Langevin equation, which describes motions centers mass clusters comprising microscopic particles. The mean, friction, and fluctuating forces in NMDPD model are directly constructed from an underlying molecular (MD) system without any scaling procedure. For validation our formulation, we construct models...

In polymer electrolyte membrane fuel cells, carbon-supported platinum (Pt/C) catalyst particles require sufficient water condensation within the nanoscale pores to effectively utilize interior Pt catalysts. Since experimental visualizations with precision of this phenomenon are not yet possible, we utilized a Pt/C particle reconstructed from segmented nanoimaging powder, which served as computational domain for lattice density functional theory (LDFT) simulation condensation. Paired uptake...

We propose a new coarse-grained (CG) molecular simulation technique based on the Mori-Zwanzig (MZ) formalism along with iterative Boltzmann inversion (IBI). Non-Markovian dissipative particle dynamics (NMDPD) taking into account memory effects is derived in pairwise interaction form from MZ-guided generalized Langevin equation. It introduction of auxiliary variables that allow for replacement non-Markovian equation Markovian one higher dimensional space. demonstrate NMDPD model exploiting...

We performed molecular dynamics (MD) simulations of the interface which is comprised self-assembled monolayer (SAM) and water solvent to investigate heat transfer characteristics. In particular, local thermal boundary conductance (TBC), an inverse so-called Kapitza resistance, at SAM–solvent was evaluated by using nonequilibrium MD (NEMD) technique in one-dimensional energy flux imposed across interface. By two kinds SAM terminal with hydrophobic hydrophilic properties, TBCs these interfaces...

We investigate the adsorption and diffusion behaviors of CO2, CH4, N2 in interfacial systems composed a polymer intrinsic microporosity (PIM-1) amorphous silica using grand canonical Monte Carlo (GCMC) molecular dynamics (MD) simulations. build model mixed matrix membranes (MMMs) with PIM-1 chains sandwiched between surfaces. Gas analysis GCMC simulations shows that gas molecules are preferentially adsorbed microcavities distributed near surfaces, resulting an increase solubility...

Thermal decomposition of ultrathin oxide layers on silicon surface was investigated with temperature programed desorption. Oxide were formed Si(100) at 400°C by exposure to O2 molecular beam. Desorption spectrum for oxygen coverages between 1.7 and 2.6 ML exhibits a single dominant peak an additional broad lower temperatures. The former corresponds stable binding states O atoms dimer bridge sites backbond sites. high intensity indicates that most are states. latter unstable state, where...

We investigate the effect of capillary condensation on gas diffusivity in porous media composed randomly packed spheres with moderate wettability. To simulate phenomena at pore scale while retaining complex networks media, we employ density functional theory (DFT) for coarse-grained lattice models. The DFT simulations reveal that condensations preferentially occur confined pores surrounded by solid walls, leading to occlusion narrow pores. Consequently, characteristic lengths partially wet...

Gas flow in nanospaces is greatly affected by the scattering behavior of gas molecules on solid surfaces, resulting unique mass transport properties. In this paper, molecular beam experiment water a graphite surface was conducted to understand their dynamics an incident energy range that corresponds thermal velocity distribution at room temperature (35–130 meV). Because large adsorption (∼100 meV), quite sensitive even within narrow range. For relatively energies, direct-inelastic and...

We investigate the mechanical properties of $\pi$-conjugated polymeric materials composed regioregular poly(3-hexylthiophene) (P3HT) and fullerene C$_{60}$ using coarse-grained molecular dynamics simulations. Specifically, we perform tensile simulations P3HT:C$_{60}$ composites with varied degrees polymerization mass fractions to obtain their stress-strain responses. Decomposition stress tensor into kinetic energy virial contributions indicates that moduli pure P3HT samples are greatly...

We develop molecular transport simulation methods that simultaneously deal with gas- and surface-phase diffusions to determine the effect of surface diffusion on overall coefficients. The phenomenon is incorporated into test particle method mean square displacement method, which are typically employed only for gas-phase transport. It found a simple cylindrical pore, coefficients in presence calculated by these two show good agreement. also confirm both reproduce analytical solution. Then,...

The scattering dynamics of oxygen molecules on perfluorosulfonic acid (PFSA) ionomer thin films was investigated using molecular dynamic simulations. We constructed PFSA with different water contents a carbon surface at 300 K and then shot into the incident angles energies corresponding to temperature range from 150 600 K. effective softness film for gas–surface collisions increased increasing hydration level film. regions exposing polymers had because polymer entanglement mobility...

A molecular beam source exploiting a small shock tube is described for potential generation of high energy in range 1–5 eV without any undesirable impurities. The performance non‐diaphragm type with an inner diameter 2 mm was evaluated by measuring the acceleration and attenuation process waves. With this installed source, we measured time‐of‐flight distributions shock‐heated beams, which demonstrated ability controlling initial pressure ratio tube.

The rapid spread of micro/nanoelectromechanical systems necessitates detailed understanding fluidics within nanoscale structures. In this paper, the dynamics a water droplet in nanochannels are analyzed using molecular simulations. As channel size decreases, shear stress between and solid wall becomes much larger than predictions based on conventional slip boundary conditions. Our analysis shows that Navier friction coefficient is quite sensitive to liquid pressure, which tends be...

We present the analysis of gas transport in micro porous layers polymer electrolyte fuel cells based on three-dimensional structure data obtained from X-ray nano computed tomography (CT). The characteristic pore size is comparable to mean free path molecules. polygonal surface representation constructed volumetric CT image using marching tetrahedrons algorithm. diffusion fluxes molecules through layer are evaluated by direct simulation Monte Carlo method, which can reproduce transition...