Xiaoning Yang

The graphene/MoS₂ composite is a functional heterostructure with broad applications that leverage the synergistic properties of its constituents. Generally, small ambient molecules might penetrate and adsorb into the interlayer of graphene/MoS₂ and interact with surface defects, leading to chemical reactions within the confined spaces. Currently, the interfacial interaction and reaction mechanisms remain largely unclear. Herein, we employed density functional theory and ab initio molecular dynamics simulations to investigate the interfacial adsorptions and reactions of O₂ and H₂O molecules at the Graphene/MoS₂ interfaces with various vacancy types of MoS₂ surfaces. Various mechanisms and pathways have been identified for the thermodynamic trends and kinetic barriers in interlayer reactions. It is demonstrated that the pristine Graphene/MoS₂ is inert for molecular interlayer adsorption. However, there are obvious chemical reactions at the defect-involved G/MoS₂ interfaces. Specifically, the dissociation of molecular oxygen can induce surface oxidation, accompanied by the restoration of the electronic properties of graphene/MoS₂. The water molecule can undergo spontaneous dissociation at the defect sites, exhibiting enhanced activity for water splitting. As compared with bare MoS₂, the hybrid interfaces of graphene/MoS₂ can alter the chemical reactivities of adsorbed molecules. This work provides new insights into the interlayer chemistry for heterojunction interfaces.

This work reveals how hybrid graphene/silica interfaces modulate the structure and dielectric behavior of confined ethanol–water mixtures. Interfacial asymmetry induces demixing and directional polarization, leading to dielectric anisotropy.

Isolated monolayer graphene can be coupled with silica (SiO ₂ ) as graphene‐based nanoelectronic devices. The fabricated heterojunction composites in moist environments have been involved in environmental monitoring, optical detection, and health sensors. However, the corresponding interfacial stability and structures between graphene and silica substrates remain unexplored. Herein, molecular simulations were applied to investigate the adhesion of graphene/SiO ₂ composite interfaces in water media. Different SiO ₂ surface types and varied SiO ₂ hydrophilicity degrees were considered. The thermodynamic free energy was simulated to characterize the interfacial interaction. The required energetic barriers associated with the graphene detachment can be determined. SiO ₂ substrates possess differential surface affinity toward graphene. The connection between the adhesion strength and the substrate types was established. Under higher hydrophilic conditions, the attached graphene sheet can easily be separated from the silica substrates. This behavior cannot be observed in dry conditions, which is attributed to competitive actions between the interfacial hydration force and the substrate interaction. The morphologic transformations and hydration structures of the graphene‐silica interface with intervening water layers were also characterized, which is critical in modulating the interface stability. Our simulation results provide new microscopic insights into the interfacial states and structures of graphene‐SiO ₂ systems in an aqueous environment.

Layered graphene oxide (GO) has emerged as an ideal membrane structure for water desalination. In GO-stacked structures, the slit gaps between GO nanosheets can serve as critical pathways for molecule permeation. Exploring the permeation mechanisms of functionalized GO nanoslits is critical for improving the separation performance. Herein, molecular simulations were performed to investigate the water permeation and ion rejection for six types of ionic solutions by considering edge-amino functionalized GO (NGO) slit membranes. The NGO slit exhibits higher ion retention while maintaining reasonable water permeability. Edge amine groups can interact strongly with water molecules and immobilize ions, thus enhancing ion rejection. The thermodynamic free energy for ion passing was simulated to explain the unique ion rejection mechanism of amine-functionalized GO slits. The thermodynamic barrier for ion rejection can be considered as the delicate combination of the ion dehydration effect and the slit-generated attraction. The ion dehydration accounts for a repulsive contribution, which is the controlling portion in governing the free-energy profile. Overall, our work is important and valuable for the development and design of new-type layered GO membranes.

The coupled relationship between carrier and phonon scattering severely limits the thermoelectric performance of n-type GeTe materials. Here, we provide an efficient strategy to enlarge grains and induce vacancy clusters for decoupling carrier-phonon scattering through the annealing optimization of n-type GeTe-based materials. Specifically, boundary migration is used to enlarge grains by optimizing the annealing time, while vacancy clusters are induced through the aggregation of Ge vacancies during annealing. Such enlarged grains can weaken carrier scattering, while vacancy clusters can strengthen phonon scattering, leading to decoupled carrier-phonon scattering. As a result, a ratio between carrier mobility and lattice thermal conductivity of ∼492.8 cm³ V^-1 s^-1 W^-1 K and a peak ZT of ∼0.4 at 473 K are achieved in Ge_0.67Pb_0.13Bi_0.2Te. This work reveals the critical roles of enlarged grains and induced vacancy clusters in decoupling carrier-phonon scattering and demonstrates the viability of fabricating high-performance n-type GeTe materials via annealing optimization.