Jian-Gang Guo

Efficient and controllable CO₂ capture and separation are essential for mitigating the greenhouse effect and improving natural-gas utilization. In this study, a two-dimensional (2D) membrane (C₂₀N₈) was designed, and a dual-regulation strategy combining temperature and surface charge was proposed to enhance CO₂ adsorption and separation, thereby enabling tunable control over molecular transport kinetics. Via molecular dynamics (MD) simulations and density functional theory (DFT) calculations, it was demonstrated that the C₂₀N₈ membrane can efficiently adsorb and separate CO₂ from a CO₂/H₂S/CH₄ mixture over a range of temperatures and charge conditions. By merely adjusting the temperature, excellent CO₂ separation capability can be achieved. The maximum CO₂ permeance can reach 6.9×10⁷ GPU (at a temperature of 1000K), and the temperature can also enhance the initial screening rate. After introducing negative charge, the maximum CO₂ permeance can reach 7.6 × 10⁷ GPU at 1000 K and 0.11e-. Under different membrane surface charge densities, the permeation energy barriers, final relative concentration profiles, and stable adsorption sites of CO₂, H₂S, and CH₄ were calculated, and the velocity distributions of CO₂ were analyzed to clarify the underlying enhancement mechanism. Finally, the relative permeation rates of the C₂₀N₈ membrane before reaching stable permeation were determined at different temperatures and charge densities. The maximum relative permeation rate is 0.289 at 0.13e- and 1200 K, identifying the condition under which steady permeation is reached most readily. These findings clarify the molecular-scale transport mechanics underlying coupled temperature-charge regulation and provide valuable guidance for the design of tunable membrane materials for CO₂ capture and separation.

The mechanical reliability of glass substrates in through-glass via (TGV) structures is critically compromised by copper diffusion. This study employs molecular dynamics simulations to elucidate the fracture mechanics governing the interaction between Cu distribution morphologies and crack propagation in glass. We distinguish between discrete atomic dispersion and cluster aggregation, revealing distinct failure mechanisms. Discrete Cu atoms exhibit a non-monotonic effect on strength: low concentrations enhance structural stability via vacancy occupation and Si–O bond strengthening, while high concentrations degrade integrity by increasing bond-angle bending potential energy. Conversely, Cu clusters act as stress concentrators that significantly reduce macroscopic load-bearing capacity. Crucially, we identify a position-dependent dual mechanism in crack propagation. Clusters located ahead of the crack tip induce crack deflection and reduce the local energy release rate, providing a shielding effect that scales inversely with the normalized distance-to-diameter ratio. In contrast, clusters in the crack wake accelerate propagation due to stress concentrations, with the acceleration magnitude positively correlated to cluster size. These findings establish a robust atomic-scale framework linking Cu morphology to fracture resistance. By quantifying the shielding and acceleration effects of Cu clusters, this work provides theoretical guidance for optimizing TGV fabrication to mitigate fracture risks in high-frequency electronic packaging.

Using the potential function method, a theoretical model of the interaction was presented, and the interaction force between atoms/ions and (doped) graphene was obtained. Based on the interaction force, the dynamical control equation of atom/ion migration was derived. The dynamical behavior of atom/ion migrating on finite-size graphene surfaces along a specific direction and the regulation of boron nitride (BN) doping on the migration behavior were studied. The results show that the atoms/ions exhibit different migration mechanical behaviors due to different lateral forces inside and at the edges of the graphene surface. In addition, near the normal equilibrium height, atoms/ions are mainly affected by the lateral force, and their migration behavior is also influenced by the initial position, initial height, initial lateral velocity, etc. Furthermore, BN doping can affect the energy barrier of atom/ion migration on the graphene surface and effectively regulate the migration behavior of atoms/ions at the edge of the graphene surface. The research results can provide a theoretical reference for graphene surface localization modification and graphene-based atom/ion screening and detection.