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B. Sha

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3 records found

Journal article (2026) - Bowen Sha, Akhilesh Soodan, Kim Maren Lompe, Gokhan Barin, Thijs J. H. Vlugt, Loukas D. Peristeras, Othonas A. Moultos
β-Cyclodextrin (β-CD)-based polymers have shown high adsorption capacities for removing per- and polyfluoroalkyl substances (PFAS) from drinking water. PFAS capture by these materials involves many physical and chemical processes, such as adsorption and inclusion complexation. Quantifying the underlying host–guest binding between CDs and PFAS nevertheless remains essential because it governs the primary inclusion step. Here, we investigated native and linker-modified CD–PFAS inclusion complexes in aqueous solution using isothermal titration calorimetry (ITC) and molecular dynamics (MD) simulations with the attach–pull–release (APR) method. We computed the Gibbs free energies of binding for α-, β-, and γ-CDs with seven linear PFAS, including perfluorocarboxylic acids and perfluorosulfonic acids, and found reasonable agreement with our experimental measurements and previously reported data. Comparison between implicit and explicit solvent calculations suggests that the apparently better agreement of the implicit solvent model for some native monomer complexes is likely due to error cancellation rather than a more transferable physical description, whereas explicit solvent is required to capture solvent-related salt and linker effects. Overall, β-CD exhibited the strongest binding affinities, whereas α-CD showed negligible affinities and γ-CD bound PFAS more weakly than β-CD. Hydrogen bonding, interaction-energy decomposition, and solvent-accessible surface area showed that host–guest hydrogen bonding cannot uniquely predict affinities, and that hydrophobic dehydration plays a dominant role in binding. We further examined how background ion concentration affects β-CD–PFAS binding and found that explicit solvent simulations capture a clear salt dependence, with Li/Merz ion parameters describing the high-salinity trend more reasonably than the Joung–Cheatham model. To mimic the local microenvironment surrounding CD units in polymers, we also examined three linker-modified β-CD models containing phenyl groups. Bind3P water correctly reproduced the experimentally reported enhancement of PFAS adsorption with increasing linker number, and energy decomposition showed that linker groups strengthen PFAS binding by enhancing local hydrophobic confinement and specific linker–guest interactions. Overall, this combined experimental and computational study provides molecular-level insight into the building blocks of cyclodextrin polymers and lays the groundwork for future in silico construction of CD polymer models for PFAS adsorption under diverse water-matrix conditions. ...
Electrochemical CO2 reduction to CO offers a sustainable route for converting CO2 into value-added chemicals and fuels. However, CO2 streams derived from industrial sources often contain SO2 impurities that severely poison conventional metal-based catalysts. Here, we report a nitrogen-doped carbon catalyst that exhibits pronounced tolerance and stability for CO2-to-CO conversion in the presence of SO2 (100–10,000 ppm). The catalyst maintains over 90% Faradaic efficiency toward CO during 8 h of electrolysis at −1.0 V vs RHE with 100 ppm of SO2, whereas Ag foil electrodes undergo rapid deactivation. Density functional theory calculations combined with surface analyses indicate that weak SO2 adsorption and the absence of stable sulfur accumulation on nitrogen-doped carbon strengthen its resistance to impurity-induced deactivation, in contrast to Ag catalysts that form Ag2S. Gas-fed tests in a membrane electrode assembly (MEA) electrolyzer further confirm that nitrogen-doped carbon sustains high CO selectivity at elevated current densities, while Ag nanoparticles suffer irreversible sulfur poisoning. These results demonstrate that nitrogen-doped carbon is intrinsically resistant to SO2-induced deactivation and highlight its potential as a robust catalyst for CO2 electroreduction under impurity-containing conditions. ...

A molecular simulation study at the microsecond scale

Journal article (2026) - Fengyi Mi, Hongjuan Sun, Wei Li, Bin Fang, Zhun Zhang, Bowen Sha, Thijs J.H. Vlugt, Othonas A. Moultos, Fulong Ning
Hydrogen can play a central role in a fossil-free energy economy, yet its implementation is hindered by the lack of safe, dense, and efficient storage methods. Hybrid H2 physisorption-hydrate formation, which combines physisorption in porous materials with encapsulation in clathrate hydrates, presents a promising route, but the fundamental synergistic mechanisms remain largely elusive. Here, we perform microsecond-scale molecular dynamics simulations to study the hybrid H2 storage process in the hydrophobic metal–organic framework ZIF-8 seeded with THF hydrate nanoparticles. The results indicate that ZIF-8 rapidly physisorbs H2, while effectively excluding H2O and THF. Our simulations reveal a dynamic, three-step hybrid storage pathway, i.e. , (1) ZIF-8 selectively adsorbs and enriches H2 within its pores, creating a high local H2 concentration; (2) The growing binary H2-THF hydrate crystals selectively capture the H2; (3) Transfer of H2 from the ZIF-8 to the hydrate until the hydrogen source transfer reaches a dynamic equilibrium. This hybrid storage method results in a total H2 storage capacity reaching 1.82 wt%, exceeding the storage capacity of either physisorption or THF-driven hydrate formation alone. These findings provide critical molecular-level insights, showing that coupling hydrophobic ZIF-8 with hydrate promoters is a highly effective strategy for developing next-generation H2 storage methods. ...