Golibjon. R. Berdiyorov

Bipyridine-based self-assembled monolayers (BPD SAMs) on Au substrates were modified via transition-metal (Ni, Co, and Cu) intercalation, with their effects compared against electron-beam-induced crosslinking.

Two-dimensional MXenes have emerged as a versatile class of materials for energy storage, electronics, and catalysis owing to their high electrical conductivity, tunable surface chemistry, and layered structure; however, the controlled synthesis of Ti3C2Tx MXene with well-defined morphology and stable surface chemistry remains a major challenge, as etching conditions strongly influence structural integrity, degree of exfoliation, and functional performance. In this study, the morphological, structural, and functional evolution of Ti3C2Tx MXene materials was systematically investigated by applying hydrofluoric acid (HF) etching at varying concentrations (6 %, 12 %, 24 %, 36 %, and 48 %) using microwave-assisted method. The impact of etching intensity on Al removal, layer delamination, and surface functionalization was examined through a multi-technique characterization approach including scanning electron microscopy (SEM), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), and energy-dispersive X-ray spectroscopy (EDS). The results reveal that an HF concentration of 24 % achieves efficient Al extraction while preserving the Ti–C framework, yielding well-exfoliated and structurally stable MXene sheets. Lower HF concentrations (6 % and 12 %) lead to incomplete etching and limited exfoliation, whereas higher concentrations (36 % and 48 %) cause over-etching and pronounced structural degradation. These findings underscore the critical role of etching conditions in tuning MXene morphology and functional properties. The ability to balance surface termination control and structural integrity via gradient etching is particularly relevant for the use of Ti3C2Tx MXenes as conductive electrodes and interfacial layers in photovoltaic and other energy-conversion devices.

Per- and polyfluoroalkyl substances (PFAS) are environmentally persistent synthetic chemicals whose strong carbon-fluorine bonds and amphiphilic molecular structure govern their interaction with carbon-based materials. In this work, density functional theory (DFT)-based simulations are employed to investigate the adsorption behavior of short-chain PFAS molecules sharing a common perfluoropropyl (C₃F₇) tail namely, perfluorobutanoic acid (PFBA), perfluoropropanesulfonic acid (PFPrS), and perfluoropropanesulfonamide (PFPrSA), on graphene-based substrates. The effects of adsorption site, vacancy defects, surface functionalization (–COOH, –NH₂, –OH), and implicit solvation are systematically examined. The results reveal that, on pristine graphene, all PFAS molecules preferentially adsorb on the basal plane compared to the edges, with PFPrSA exhibiting the strongest adsorption among the studied species. The introduction of a single-vacancy defect significantly enhances adsorption energies due to the formation of localized reactive sites, whereas enlargment to a divacancy yeiled only marginal additional stabilization. Among the surface functional groups, hydroxyl (–OH) functionalization provides the most effective enhancement of adsorption compared to carboxyl (–COOH) and amine (–NH₂) groups. The inclusion of implicit solvation consistently reduces adsorption energies relative to vacuum conditions, reflecting solvent screening effects. These findings provide atomistic insight into PFAS–graphene interactions and provide guidance for the design of carbon-based materials for environmental remediation.

Graphene-based materials are promising candidates for hydrogen storage and filtration owing to their high surface area and tunable surface chemistry. In this study, we investigate the adsorption and diffusion behavior of hydrogen molecules on pristine, nitrogen-doped (graphitic and pyridinic), defective, and functionalized graphene using reactive force field molecular dynamics simulations. The results demonstrate that nitrogen doping significantly strengthens H2–surface interactions, leading to increased hydrogen coordination and suppressed surface diffusion compared to pristine graphene. The influence of water, which is inevitably present under realistic conditions, is also examined and shown to further reduce hydrogen mobility by limiting surface accessibility. In addition, we analyze the effect of oxygen-related surface functionality by introducing OH functional groups, which enhance hydrogen–surface interactions and further suppress hydrogen diffusion. Adsorption energy calculations confirm that both nitrogen dopants and OH functional groups increase the affinity of the graphene surface toward adsorbates, while water molecules bind more strongly than hydrogen, providing a mechanistic explanation for the reduced hydrogen mobility observed under hydrated conditions. This study provides fundamental insights into the effects of both doping and solvation on hydrogen mobility, offering guidance for the rational design of graphene-based materials for efficient hydrogen storage and separation technologies.