Publications by authors named "Sheng Dai"

489 Publications

Molecular Dynamics Simulations of Complexation of Am(III) with a Preorganized Dicationic Ligand in an Ionic Liquid.

J Phys Chem B 2021 Jul 22. Epub 2021 Jul 22.

Department of Chemistry, University of California, Riverside, California 92521, United States.

Preorganized ligands with imidazolium arms have been found to be highly selective in extracting Am(III) into ionic liquids (ILs), but the detailed structure and mechanism of the complexation process in the ionic solvation environment are unclear. Here, we carry out molecular dynamics simulation of the complexation of Am(III) with a preorganized 1,10-phenanthroline-2,9-dicarboxamide complexant (L) functionalized with alkyl chains and imidazolium cations in the butylmethylimidazolium bistriflimide ([BMIM][NTf]) IL. Both Am:L (1:1) and Am:L (1:2) complexes are examined. In the absence of the ligand, Am(III) is found to be coordinated by six NTf anions via nine O donors in the first solvation shell. In the Am:L complex, Am(III) is coordinated to the ligand via two O donors and four NTf anions via seven O donors in the first coordination shell. In the Am:L complex, Am(III) is coordinated to the two ligands via four O donors and four NTf anions via five O donors. The imidazolium arms of the ligands play an important role in the secondary solvation environment by attracting NTf anions closer to the metal center. As a result, we find that the binding free energy for the second L ligand is twice that for the first L ligand, making the Am:L complex significantly more stable than the Am:L complex. This work highlights the multiple factors and tunability in using preorganized ligands with charged functional groups in an ionic solvation environment, which could hold the key to achieving desired selectivity in ion extraction efficiency.
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http://dx.doi.org/10.1021/acs.jpcb.1c04410DOI Listing
July 2021

Significant Improvement of Catalytic Performance for Chlorinated Volatile Organic Compound Oxidation over RuO Supported on Acid-Etched CoO.

Environ Sci Technol 2021 Jul 16. Epub 2021 Jul 16.

Key Laboratory for Advanced Materials and Research Institute of Industrial Catalysis, School of Chemistry & Molecular Engineering, East China University of Science and Technology, Shanghai 200237, P. R. China.

Ru catalysts have attracted increasing attention in catalytic oxidation of chlorinated volatile organic compounds (CVOCs). However, the development of Ru catalysts with high activity and thermal stability for CVOC oxidation still poses significant challenges due to their restrictive relationship. Herein, a strategy for constructing surface defects on CoO support by acid etching was utilized to strengthen the interaction between active RuO species and the CoO support. Consequently, both the dispersity and thermal stability of RuO species were significantly improved, achieving both high activity and stability of Ru catalysts for CVOC oxidation. The optimized Ru catalyst on the HF-etched CoO support (Ru/CoO-F) achieved complete oxidation of vinyl chloride at 260 °C under 30 000 mL·g·h, which was lower than 300 °C for the Ru catalyst on the original CoO (Ru/CoO). More importantly, the Ru species on the Ru/CoO-F catalyst were hardly lost after calcination at 500-700 °C and even reacting at 650 °C for 120 h. On this basis, the polychlorinated byproducts over the Ru/CoO-F catalyst were almost completely effaced by phosphate modification on the catalyst surface. These findings show that the method combining acid etching of the support and phosphate modification provides a strategy for the advancement of catalyst design for CVOC oxidation.
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http://dx.doi.org/10.1021/acs.est.1c02970DOI Listing
July 2021

CO Chemisorption Behavior of Coordination-Derived Phenolate Sorbents.

ChemSusChem 2021 Jul 2;14(14):2784. Epub 2021 Jul 2.

Department of Chemistry, Joint Institute for Advanced Materials, The University of Tennessee, 37996, Knoxville, TN, USA.

Invited for this month's cover is the group of Sheng Dai at the Oak Ridge National Laboratory. The image shows the CO chemisorption behavior of coordination-derived phenolate sorbents. The Communication itself is available at 10.1002/cssc.202100666.
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http://dx.doi.org/10.1002/cssc.202101255DOI Listing
July 2021

X-ray scattering reveals ion clustering of dilute chromium species in molten chloride medium.

Chem Sci 2021 May 19;12(23):8026-8035. Epub 2021 May 19.

Chemical Sciences Division, Oak Ridge National Laboratory P. O. Box 2008 Oak Ridge TN 37831 USA

Enhancing the solar energy storage and power delivery afforded by emerging molten salt-based technologies requires a fundamental understanding of the complex interplay between structure and dynamics of the ions in the high-temperature media. Here we report results from a comprehensive study integrating synchrotron X-ray scattering experiments, molecular dynamics simulations and rate theory concepts to investigate the behavior of dilute Cr metal ions in a molten KCl-MgCl salt. Our analysis of experimental results assisted by a hybrid transition state-Marcus theory model reveals unexpected clustering of chromium species leading to the formation of persistent octahedral Cr-Cr dimers in the high-temperature low Cr concentration melt. Furthermore, our integrated approach shows that dynamical processes in the molten salt system are primarily governed by the charge density of the constituent ions, with Cr exhibiting the slowest short-time dynamics. These findings challenge several assumptions regarding specific ionic interactions and transport in molten salts, where aggregation of dilute species is not statistically expected, particularly at high temperature.
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http://dx.doi.org/10.1039/d1sc01224jDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8208131PMC
May 2021

Role of Organic Fluoride Salts in Stabilizing Niobium Oxo-Clusters Catalyzing Epoxidation.

Langmuir 2021 Jul 29;37(27):8190-8203. Epub 2021 Jun 29.

Key Laboratory for Advanced Materials, Research Institute of Industrial Catalysis, East China University of Science and Technology, Shanghai 200237, China.

We present here that easily available organic salts can stabilize/modify niobium (Nb) oxo-clusters. The as-synthesized Nb oxo-clusters have been characterized by various methods. These Nb oxo-clusters were catalytically active for the epoxidation of allylic alcohols and olefins with HO as an oxidant. Notably, [email protected] appeared as highly dispersed nanosized particles and showed the highest catalytic activity, which can be attributed to the following reasons on the basis of characterization. First, the strong coordination of fluorine ions with Nb sites and the steric protection with bulky organic cations led to high stabilization and dispersion of the oxo-clusters in the course of the reaction. Second, a hydrogen-bond interaction between the coordinated fluorine atom and the -OH group of allylic alcohol favored the epoxidation reaction. Third, the electron density of Nb sites decreased due to the strong electron-withdrawing ability of F adjacent to Nb sites, thus promoting the electrophilic oxygen transfer to the C═C bond.
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http://dx.doi.org/10.1021/acs.langmuir.1c00893DOI Listing
July 2021

Methane Hydrate Crystallization on Sessile Water Droplets.

J Vis Exp 2021 May 26(171). Epub 2021 May 26.

Earth and Atmospheric Sciences, Georgia Institute of Technology;

This paper describes a method to form methane hydrate shells on water droplets. In addition, it provides blueprints for a pressure cell rated to 10 MPa working pressure, containing a stage for sessile droplets, a sapphire window for visualization, and temperature and pressure transducers. A pressure pump connected to a methane gas cylinder is used to pressurize the cell to 5 MPa. The cooling system is a 10 gallon (37.85 L) tank containing a 50% ethanol solution cooled via ethylene glycol through copper coils. This setup enables the observation of the temperature change associated with hydrate formation and dissociation during cooling and depressurization, respectively, as well as visualization and photography of the morphologic changes of the droplet. With this method, rapid hydrate shell formation was observed at ~-6 °C to -9 °C. During depressurization, a 0.2 °C to 0.5 °C temperature drop was observed at the pressure/temperature (P/T) stability curve due to exothermic hydrate dissociation, confirmed by visual observation of melting at the start of the temperature drop. The "memory effect" was observed after repressurizing to 5 MPa from 2 MPa. This experimental design allows the monitoring of pressure, temperature, and morphology of the droplet over time, making this a suitable method for testing various additives and substrates on hydrate morphology.
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http://dx.doi.org/10.3791/62686DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8227821PMC
May 2021

Formation of three-dimensional bicontinuous structures via molten salt dealloying studied in real-time by in situ synchrotron X-ray nano-tomography.

Nat Commun 2021 Jun 9;12(1):3441. Epub 2021 Jun 9.

Department of Materials Science and Chemical Engineering, Stony Brook University, Stony Brook, NY, USA.

Three-dimensional bicontinuous porous materials formed by dealloying contribute significantly to various applications including catalysis, sensor development and energy storage. This work studies a method of molten salt dealloying via real-time in situ synchrotron three-dimensional X-ray nano-tomography. Quantification of morphological parameters determined that long-range diffusion is the rate-determining step for the dealloying process. The subsequent coarsening rate was primarily surface diffusion controlled, with Rayleigh instability leading to ligament pinch-off and creating isolated bubbles in ligaments, while bulk diffusion leads to a slight densification. Chemical environments characterized by X-ray absorption near edge structure spectroscopic imaging show that molten salt dealloying prevents surface oxidation of the metal. In this work, gaining a fundamental mechanistic understanding of the molten salt dealloying process in forming porous structures provides a nontoxic, tunable dealloying technique and has important implications for molten salt corrosion processes, which is one of the major challenges in molten salt reactors and concentrated solar power plants.
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http://dx.doi.org/10.1038/s41467-021-23598-8DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8190292PMC
June 2021

A Polymer-Assisted Spinodal Decomposition Strategy toward Interconnected Porous Sodium Super Ionic Conductor-Structured Polyanion-Type Materials and Their Application as a High-Power Sodium-Ion Battery Cathode.

Adv Sci (Weinh) 2021 Jun 20;8(11):e2004943. Epub 2021 Mar 20.

Chemical Sciences Division, Oak Ridge National Laboratory, Oak Ridge, TN, 37831, USA.

A general polymer-assisted spinodal decomposition strategy is used to prepare hierarchically porous sodium super ionic conductor (NASICON)-structured polyanion-type materials (e.g., Na V (PO ) , Li V (PO ) , K V (PO ) , Na MnV(PO ) , and Na TiV(PO ) ) in a tetrahydrofuran/ethanol/H O synthesis system. Depending on the boiling point of solvents, the selective evaporation of the solvents induces both macrophase separation via spinodal decomposition and mesophase separation via self-assembly of inorganic precursors and amphiphilic block copolymers, leading to the formation of hierarchically porous structures. The resulting hierarchically porous Na V (PO ) possessing large specific surface area (≈77 m g ) and pore volume (≈0.272 cm g ) shows a high specific capacity of 117.6 mAh g at 0.1 C achieving the theoretical value and a long cycling life with 77% capacity retention over 1000 cycles at 5 C. This method presented here can open a facile avenue to synthesize other hierarchically porous polyanion-type materials.
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http://dx.doi.org/10.1002/advs.202004943DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8188202PMC
June 2021

Polymer-Grafted Porous Silica Nanoparticles with Enhanced CO Permeability and Mechanical Performance.

ACS Appl Mater Interfaces 2021 Jun 6;13(23):27411-27418. Epub 2021 Jun 6.

Chemical Sciences Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, United States.

Three different types of polymer ligands, poly(methyl methacrylate) (PMMA), poly(methyl methacrylate--poly(ethylene glycol)methyl ether methacrylate) (PMMA--PEGMEMA), and poly(ionic liquid)s (PIL), were grafted onto the surface of 15 nm solid and large hollow porous silica nanoparticles (average particle size ∼60 nm) by surface-initiated atom transfer radical polymerization (SI-ATRP) to demonstrate the enhanced carbon dioxide (CO) permeability as well as mechanical properties. After characterizing the purified products, free-standing bulk films were fabricated by the solvent-casting method. The poly(ionic liquid) nanocomposite films exhibited a much higher carbon dioxide permeance than PMMA and PMMA--PEGMEMA systems with a similar silica content. Also, the hollow silica-mixed matrix membranes showed a significant enhancement in CO permeability compared to the 15 nm solid silica films because of the pore structur. Despite the transparency loss due to the scattering of larger particle sizes, the hollow silica particle brush films exhibited the same mechanical properties as the 15 nm solid silica-derived ones.
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http://dx.doi.org/10.1021/acsami.1c04342DOI Listing
June 2021

Photoinduced Strong Metal-Support Interaction for Enhanced Catalysis.

J Am Chem Soc 2021 Jun 3;143(23):8521-8526. Epub 2021 Jun 3.

Department of Chemistry, The University of Tennessee, Knoxville, Tennessee 37996, United States.

Strong metal-support interaction (SMSI) construction is a pivotal strategy to afford thermally robust nanocatalysts in industrial catalysis, but thermally induced reactions (>300 °C) in specific gaseous atmospheres are generally required in traditional procedures. In this work, a photochemistry-driven methodology was demonstrated for SMSI construction under ambient conditions. Encapsulation of Pd nanoparticles with a TiO overlayer, the presence of Ti species, and suppression of CO adsorption were achieved upon UV irradiation. The key lies in the generation of separated photoinduced reductive electrons (e) and oxidative holes (h), which subsequently trigger the formation of Ti species/oxygen vacancies (O) and then interfacial Pd-O-Ti sites, affording a Pd/TiO SMSI with enhanced catalytic hydrogenation efficiency. The as-constructed SMSI layer was reversible, and the photodriven procedure could be extended to Pd/ZnO and Pt/TiO.
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http://dx.doi.org/10.1021/jacs.0c12817DOI Listing
June 2021

Comparative genomic signatures in young and old Chinese patients with colorectal cancer.

Cancer Med 2021 Jul 26;10(13):4375-4386. Epub 2021 May 26.

Division of Colorectal Surgery, Sir Run Run Shaw Hospital, Zhejiang University School of Medicine, Hangzhou, China.

Background: Occurrence at a young age is known to be associated with unique clinical features in colorectal cancer (CRC). However, the genomic differences between young and old patients with CRC are not well elucidated and, to the best of our knowledge, have never been investigated in a Chinese population.

Methods: Tumor tissue samples from 29 young (age ≤50 years) and 46 old (age >50 years) patients with CRC were collected. Targeted sequencing of 808 cancer-related genes was conducted to characterize the genomic landscape for Chinese CRC.

Results: Overall, mutational profiles exhibited notable differences between the two groups. In particular, APC and PIK3CA mutations were more frequently observed in old patients (p = 0.009 and p = 0.012, respectively), while SMAD4 mutations tended to occur in young patients (p = 0.054). Mutation loci distributions of KRAS in the young cohort differed from those in the old cohort, and a higher frequency of KRAS codon 12 mutations was potentially associated with a young age (p = 0.076). The frequencies of clinically actionable alterations were analyzed by defined age categories, which unveiled a distinctive targeted genomic profile in the young group. Furthermore, among patients with mismatch repair-proficient (pMMR) CRC, tumor mutation burden (TMB) was positively correlated with age (Pearson's r = 0.306, p = 0.011), and genomic alterations associated with high TMB in young patients differentiated from those in old patients.

Conclusions: These findings revealed different molecular characterization between young and old Chinese patients with CRC, which may provide novel insights for the personalized treatment of CRC.
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http://dx.doi.org/10.1002/cam4.3987DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8267122PMC
July 2021

Unraveling Local Structure of Molten Salts via X-ray Scattering, Raman Spectroscopy, and Molecular Dynamics.

J Phys Chem B 2021 Jun 26;125(22):5971-5982. Epub 2021 May 26.

Chemical Sciences Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, United States.

In this work, we resolve a long-standing issue concerning the local structure of molten MgCl by employing a multimodal approach, including X-ray scattering and Raman spectroscopy, along with the theoretical modeling of the experimental spectra based on molecular dynamics (AIMD) simulations utilizing several density functional theory (DFT) methods. We demonstrate the reliability of AIMD simulations in achieving excellent agreement between the experimental and simulated spectra for MgCl and 50 mol % MgCl + 50 mol % KCl, and ZnCl, thus allowing structural insights not directly available from experiment alone. A thorough computational analysis using five DFT methods provides a convergent view that octahedrally coordinated magnesium in pure MgCl upon melting preferentially coordinates with five chloride anions to form distorted square pyramidal polyhedra that are connected via corners and to a lesser degree via edges. This is contrasted with the results for ZnCl, which does not change its tetrahedral coordination on melting. Although the five-coordinate MgCl complex was not considered in the early literature, together with an increasing tendency to form a tetrahedrally coordinated complex with decreasing the MgCl content in the mixture with alkali metal chloride systems, current work reconciles the results of most previous seemingly contradictory experimental studies.
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http://dx.doi.org/10.1021/acs.jpcb.1c03786DOI Listing
June 2021

CO Chemisorption Behavior of Coordination-Derived Phenolate Sorbents.

ChemSusChem 2021 Jul 1;14(14):2854-2859. Epub 2021 Jun 1.

Department of Chemistry, Joint Institute for Advanced Materials, The University of Tennessee, 37996, Knoxville, TN, USA.

CO chemisorption via C-O bond formation is an efficient methodology in carbon capture especially using phenolate-based ionic liquids (ILs) as the sorbents to afford carbonate products. However, most of the current IL systems involve alkylphosphonium cations, leading to side reactions via the ylide intermediate pathway. It is important to figure out the CO chemisorption behavior of phenolate-derived sorbents using inactive and easily accessible cation counterparts without active protons. Herein, phenolate-based systems were constructed via coordination between alkali metal cations with crown ethers to avoid the participation of active protons in CO chemisorption. Reaction pathway study revealed that CO uptake could be achieved by O-C bond formation to afford carbonate. CO uptake capacity and reaction enthalpy were significantly influenced by the coordination effect, alkali metal types, and alkyl groups on the benzene ring.
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http://dx.doi.org/10.1002/cssc.202100666DOI Listing
July 2021

High-entropy materials for catalysis: A new frontier.

Authors:
Yifan Sun Sheng Dai

Sci Adv 2021 May 12;7(20). Epub 2021 May 12.

Chemical Sciences Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831, USA.

Entropy plays a pivotal role in catalysis, and extensive research efforts have been directed to understanding the enthalpy-entropy relationship that defines the reaction pathways of molecular species. On the other side, surface of the catalysts, entropic effects have been rarely investigated because of the difficulty in deciphering the increased complexities in multicomponent systems. Recent advances in high-entropy materials (HEMs) have triggered broad interests in exploring entropy-stabilized systems for catalysis, where the enhanced configurational entropy affords a virtually unlimited scope for tailoring the structures and properties of HEMs. In this review, we summarize recent progress in the discovery and design of HEMs for catalysis. The correlation between compositional and structural engineering and optimization of the catalytic behaviors is highlighted for high-entropy alloys, oxides, and beyond. Tuning composition and configuration of HEMs introduces untapped opportunities for accessing better catalysts and resolving issues that are considered challenging in conventional, simple systems.
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http://dx.doi.org/10.1126/sciadv.abg1600DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8115918PMC
May 2021

Engineered Human Heavy-Chain Ferritin with Half-Life Extension and Tumor Targeting by PAS and RGDK Peptide Functionalization.

Pharmaceutics 2021 Apr 9;13(4). Epub 2021 Apr 9.

School of Chemical Engineering and Advanced Materials, The University of Adelaide, Adelaide SA5005, Australia.

Ferritin, one of the most investigated protein nanocages, is considered as a promising drug carrier because of its advantageous stability and safety. However, its short half-life and undesirable tumor targeting ability has limited its usage in tumor treatment. In this work, two types of functional peptides, half-life extension peptide PAS, and tumor targeting peptide RGDK (Arg-Gly-Asp-Lys), are inserted to human heavy-chain ferritin (HFn) at C-terminal through flexible linkers with two distinct enzyme cleavable sites. Structural characterizations show both HFn and engineered HFns can assemble into nanoparticles but with different apparent hydrodynamic volumes and molecular weights. RGDK peptide enhanced the internalization efficiency of HFn and showed a significant increase of growth inhibition against 4T1 cell line in vitro. Pharmacokinetic study in vivo demonstrates PAS peptides extended ferritin half-life about 4.9 times in Sprague Dawley rats. RGDK peptides greatly enhanced drug accumulation in the tumor site rather than in other organs in biodistribution analysis. Drug loaded PAS-RGDK functionalized HFns curbed tumor growth with significantly greater efficacies in comparison with drug loaded HFn.
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http://dx.doi.org/10.3390/pharmaceutics13040521DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8070472PMC
April 2021

Strong Enhancement of Nanoconfined Water Mobility by a Structure Breaking Salt.

J Phys Chem Lett 2021 Apr 21;12(16):4038-4044. Epub 2021 Apr 21.

Neutron Scattering Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, United States.

For the majority of the water present on earth, the two most important factors influencing its behavior are confinement, in either inorganic or organic matrixes, and the presence of solutes. Here, we investigate the effect of confinement in 3 nm pores on water diffusivity in aqueous solutions with archetypical solutes, a structure making (kosmotrope) NaCl and a structure breaking (chaotrope) KCl, up to 1.0 M in concentration. The water diffusivity in bulk aqueous solutions in such a concentration range is known to decrease very slightly in the presence of NaCl and increase very slightly in the presence of KCl. However, here we observe the water diffusivity in confined HO-KCl increases by a factor of 2 compared to the pure water diffusivity in the same confinement. This unusually strong cumulative effect of confinement and a structure breaking additive may have profound implications for the mobility and transport of aqueous species in nature.
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http://dx.doi.org/10.1021/acs.jpclett.1c00461DOI Listing
April 2021

Benzene Ring Knitting Achieved by Ambient-Temperature Dehalogenation via Mechanochemical Ullmann-Type Reductive Coupling.

Adv Mater 2021 May 19;33(21):e2008685. Epub 2021 Apr 19.

Department of Chemistry, Joint Institute for Advanced Materials, University of Tennessee, Knoxville, TN, 37996, USA.

The current approaches capable of affording conjugated porous networks (CPNs) still rely on solution-based coupling reactions promoted by noble metal complexes or Lewis acids, on-surface polymerization conducted in ultrahigh-vacuum environment at very high temperatures (>200 °C), or mechanochemical Scholl-type reactions limited to electron-rich substrates. To develop simple and scalable approaches capable of making CPNs under neat and ambient conditions, herein, a novel and complementary method to the current oxidative Scholl coupling processes is demonstrated to afford CPNs via direct aromatic ring knitting promoted by mechanochemical Ullmann-type reactions. The key to this strategy lies in the dehalogenation of aromatic halides in the presence of Mg involving the formation of Grignard reagent intermediates. Products (Ph-CPN-1) obtained via direct CC bond formation between 1,2,4,5-tetrabromobenzene (TBB) monomer feature high surface areas together with mesoporous architecture. The versatility of this approach is confirmed by the successful construction of various CPNs via knitting of the corresponding aromatic rings (e.g., pyrene and triphenylene), and even highly crystalline graphite product was obtained. The CPNs exhibit good electrochemical performance as the anode material in lithium-ion batteries (LIBs). This approach expands the frontiers of CPN synthesis and provides new opportunities to their scalable applications.
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http://dx.doi.org/10.1002/adma.202008685DOI Listing
May 2021

Design of Graphene/Ionic Liquid Composites for Carbon Capture.

ACS Appl Mater Interfaces 2021 Apr 8;13(15):17511-17516. Epub 2021 Apr 8.

Department of Chemistry, University of California, Riverside, California 92521, United States.

Pore size is a crucial factor impacting gas separation in porous separation materials, but how to control the pore size to optimize the separation performance remains a challenge. Here, we propose a design of graphene/ionic liquid composites with tunable slit pore sizes, where cations and anions of ionic liquids are intercalated between graphene layers. By varying the sizes of the ions, we show from first-principles density functional theory calculations that the accessible pore size can be tuned from 3.4 to 6.0 Å. Grand canonical Monte Carlo simulations of gas sorption find that the composite materials possess high CO uptake at room temperature and 1 bar (up to ∼8.5 mmol/g). Further simulations of the sorption of gas mixtures reveal that high CO/N and CO/CH adsorption selectivities can be obtained when the accessible pore size is <5 Å. This work suggests a new strategy to achieve tunable pore sizes via the graphene/IL composites for highly selective CO/N and CO/CH adsorption.
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http://dx.doi.org/10.1021/acsami.1c01242DOI Listing
April 2021

Interactions of an Imine Polymer with Nanoporous Silica and Carbon in Hybrid Adsorbents for Carbon Capture.

Langmuir 2021 Apr 5;37(15):4622-4631. Epub 2021 Apr 5.

Center for Nanophase Materials Sciences, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, United States.

Efficient carbon capture from stationary point sources can be achieved using hybrid adsorbents comprising nanoporous substrates coated with imine polymers. The physical properties of the CO-adsorbing, nanodispersed polymers are altered by their interactions with the substrate, which in turn may impact their capture capacity. We study silica and carbon nanoporous substrates with different pore morphologies that were impregnated with polymer imine with the goal of characterizing the polymer dispersions in the pores. For silica and carbon samples, the mean densities of confined poly(ethylene imine) (PEI) were measured as functions of polymer loading and temperature using small-angle neutron scattering. Strong densification is found for imine polymers imbibed in mesoporous carbon. PEI in nanoporous silica does not experience this strong densification. At high loadings, plugs form, preferably at the pore throats, and can reduce accessible porosity. CO capture measurements show that PEI interactions with the substrate play an important role. PEI in carbon shows the highest capture capacity at low temperatures and the lowest CO adsorption at high temperatures, making it well-suited for temperature swing adsorption applications.
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http://dx.doi.org/10.1021/acs.langmuir.1c00305DOI Listing
April 2021

Cell-friendly photo-functionalized TiO nano-micro-honeycombs for selectively preventing bacteria and platelet adhesion.

Mater Sci Eng C Mater Biol Appl 2021 Apr 25;123:111996. Epub 2021 Feb 25.

Institute of Biomaterials and Surface Engineering, Key Lab. for Advanced Technologies of Materials, Ministry of Education, Southwest Jiaotong University, Chengdu 610031, China.

Titanium dioxide (TiO) is a widely used biomaterial. It is a great challenge to confer antibacterial and antithrombotic properties to TiO while maintaining its cell affinity. Here, we developed a new strategy to achieve the above goal by comprehensively controlling the chemical cues and geometrical cues of the surface of TiO. Using colloidal etching technology and UV irradiation treatment, we obtained the photofunctionalized nano-micro-honeycomb structured TiO. The honeycomb structured increased the photocatalytic activity of TiO, which endowed TiO with photo-induced superhydrophilicity to inhibit bacterial adhesion. The high photocatalytic activity also induced the strong photocatalytic oxidation of TiO surface organic adsorbates to suppress fibrinogen and platelet attachment. In addition, owing to the micropore trapping-isolation effect on the bacteria and the nano-frames' contact guidance effect on the growth and spreading of platelet pseudopods, the honeycomb structure also shows a considerable inhibiting effect on bacterial and platelet adhesion. Therefore, due to the controlled chemical and geometrical cues' synergistic effect, the photo-functionalized TiO honeycomb structure shows excellent bacterial-adhesion resistance and antithrombotic properties. More importantly, the photo-functionalized TiO honeycomb did not inhibit the adhesion and growth of endothelial cells (ECs) after culturing for 3 d, indicating a good cell affinity that the traditional antifouling surfaces do not possess.
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http://dx.doi.org/10.1016/j.msec.2021.111996DOI Listing
April 2021

Hierarchical Lignin-Based Carbon Matrix and Carbon Dot Composite Electrodes for High-Performance Supercapacitors.

ACS Omega 2021 Mar 10;6(11):7851-7861. Epub 2021 Mar 10.

Center for Renewable Carbon, Institute of Agriculture, The University of Tennessee, Knoxville, Tennessee 37996, United States.

This work adopts an efficient chemical-wet method to build a three-dimensional (3D) carbon composite as an electrode material for high-performance supercapacitors (SCs). Carbon dots (CDs), prepared by thermal pyrolysis of citric acid and urea under microwaves at 280 °C, are homogeneously coated onto lignin-based activated carbons (ACs), thus forming the 3D composites possessing an interior surface decorated with CD binding sites. Benefiting from the hydrophilicity and ultrafine size of CDs, the affinity of the electrode surface toward aqueous electrolytes is significantly improved with the addition of CDs, leading to the enhanced effective surface area (i.e., abundant electroactive sites) and a decreased ionic diffusion path. The capacitance of the SCs is improved from 125.8 to 301.7 F g with CD addition. The SC with CD addition possesses improved cycle stability with a coulombic efficiency around 100% after 3000 cycles. After cycling, the ion diffusion coefficient of the [email protected] electrode is enhanced by 25.5 times as compared to that of the pristine AC one. This unique and robust carbon framework can be utilized for engineering the desired pore structure and micropore/mesopore fraction within the AC electrodes. This strategy of [email protected] electrodes demonstrates a promising route for using renewable porous carbon materials in advanced energy-storage devices.
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http://dx.doi.org/10.1021/acsomega.1c00448DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7992182PMC
March 2021

Engineering Permanent Porosity into Liquids.

Adv Mater 2021 May 26;33(18):e2005745. Epub 2021 Mar 26.

Department of Chemistry, University of Cambridge, Lensfield Road, Cambridge, CB2 1EW, UK.

The possibility of engineering well-defined pores into liquid materials is fascinating from both a conceptual and an applications point of view. Although the concept of porous liquids was proposed in 2007, these materials had remained hypothetical due to the technical challenges associated with their synthesis. Over the past five years, however, reports of the successful construction of porous liquids based on existing porous scaffolds, such as coordination cages, organic cages, metal-organic frameworks, porous carbons, zeolites, and porous polymers, have started to emerge. Here, the focus is on these early reports of porous liquids as prototypes in the field, classified according to the previously defined types of porous liquids. Particular attention will be paid to design strategies and structure-property relationships. Porous liquids have already exhibited promising applications in gas storage, transportation, and chemical separations. Thus, they show great potential for use in the chemical industry. The challenges of preparation, scale-up, volatility, thermal and chemical stability, and competition with porous solids will also be discussed.
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http://dx.doi.org/10.1002/adma.202005745DOI Listing
May 2021

Dual-response quadratic model for optimisation of electricity generation and chlorophenol degradation by electro-degradative in microbial fuel cell system.

Environ Technol 2021 Apr 1:1-14. Epub 2021 Apr 1.

Department of Chemical Engineering, Brunel University London, Uxbridge, UK.

The interactions within microbial, chemical and electronic elements in microbial fuel cell (MFC) system can be crucial for its bio-electrochemical activities and overall performance. Therefore, this study explored polynomial models by response surface methodology (RSM) to better understand interactions among anode pH, cathode pH and inoculum size for optimising MFC system for generation of electricity and degradation of 2,4-dichlorophenol. A statistical central composite design by RSM was used to develop the quadratic model designs. The optimised parameters were determined and evaluated by statistical results and the best MFC systematic outcomes in terms of current generation and chlorophenol degradation. Statistical results revealed that the optimum current density of 106 mA/m could be achieved at anode pH 7.5, cathode pH 6.3-6.6 and 21-28% for inoculum size. Anode-cathode pHs interaction was found to positively influence the current generation through extracellular electron transfer mechanism. The phenolic degradation was found to have lower response using these three parameter interactions. Only inoculum size-cathode pH interaction appeared to be significant where the optimum predicted phenolic degradation could be attained at pH 7.6 for cathode pH and 29.6% for inoculum size.
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http://dx.doi.org/10.1080/09593330.2021.1907451DOI Listing
April 2021

Overcoming the phase separation within high-entropy metal carbide by poly(ionic liquid)s.

Chem Commun (Camb) 2021 Apr 16;57(30):3676-3679. Epub 2021 Mar 16.

The Key Laboratory of Synthetic and Biological Colloids, Ministry of Education, School of Chemical and Material Engineering, Jiangnan University, Wuxi 214122, Jiangsu, China.

High-entropy crystalline materials are attracting more attention. In principle, high-entropy metal carbides (HMCs) that contain five or more metal ions, possess more negative free energy value during catalysis. But its preparation is challenging because of the immiscibility of multi metal cations in a single carbide solid solution. Here, a rational strategy for preparing HMC is proposed via a coordination-assisted crystallization process in the presence of Br-based poly(ionic liquids). Through this method, MoWVCrNbC nanoparticles, with a single cubic phase structure, incorporated on porous carbon, are obtained ([email protected]). By combination of well dispersed small particle size (∼4 nm), high surface area (∼270 m g), and high-entropy phase, [email protected] can function as a promising catalyst for the dehydrogenation of ethylbenzene. Unexpected activity (EB conv.: 73%) and thermal stability (>100 h on steam) at 450 °C are observed. Such a facile synthetic strategy may inspire the fabrication of other types of HMCs for more specific tasks.
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http://dx.doi.org/10.1039/d1cc00497bDOI Listing
April 2021

Deep Learning Accelerated Determination of Hydride Locations in Metal Nanoclusters.

Angew Chem Int Ed Engl 2021 May 21;60(22):12289-12292. Epub 2021 Apr 21.

Department of Chemistry, University of California, Riverside, CA, 92521, USA.

Although the coordinates of the metal atoms can be accurately determined by X-ray crystallography, locations of hydrides in metal nanoclusters are challenging to determine. In principle, neutron crystallography can be employed to pinpoint the hydride positions, but it requires a large crystal and a neutron source, which prevents its routine use. Here, we present a deep-learning approach that can accelerate determination of hydride locations in single-crystal X-ray structure of metal nanoclusters of different sizes. We demonstrate the efficiency of our method in predicting the most probable hydride sites and their combinations to determine the total structure for two recently reported copper nanoclusters, [Cu H (SPhCl ) ] and [Cu (S Bu) S Cl H ] whose hydride locations have not been determined by neutron diffraction. Our method can be generalized and applied to other metal systems, thereby eliminating a bottleneck in atomically precise metal hydride nanochemistry.
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http://dx.doi.org/10.1002/anie.202100407DOI Listing
May 2021

Pyrvinium pamoate inhibits cell proliferation through ROS-mediated AKT-dependent signaling pathway in colorectal cancer.

Med Oncol 2021 Feb 8;38(2):21. Epub 2021 Feb 8.

Department of Colorectal Surgery, School of Medicine, Sir Run Run Shaw Hospital, Zhejiang University, 3 Qingchun East Road, Hangzhou, Zhejiang, 310016, People's Republic of China.

The use of the anthelmintic drug pyrvinium pamoate (PP) in cancer therapy has been extensively investigated in the last decade. PP has been shown to have an inhibitory effect in colorectal cancer (CRC), but the underlying mechanism remains elusive. We aimed to investigate the antitumor activity and mechanisms of PP in CRC. In the present study, we used CCK-8 assays, colony formation assays, and western blotting to reveal that PP effectively suppressed CRC cell proliferation and the AKT-dependent signaling pathway in a concentration-dependent and time-dependent manner. Flow cytometric analysis and fluorescence microscopy demonstrated that PP increased intracellular reactive oxygen species (ROS) accumulation. We found that the inhibitory effect of PP on cell proliferation and AKT protein expression induced by PP could be partially reversed by N-acetyl-L-cysteine (NAC), an ROS scavenger. In addition, the results also demonstrated that PP inhibited cell migration by modulating epithelial-to-mesenchymal transition (EMT)-related proteins, including E-cadherin and vimentin. In conclusion, our data suggested that PP effectively inhibited cell proliferation through the ROS-mediated AKT-dependent signaling pathway in CRC, further providing evidence for the use of PP as an antitumor agent.
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http://dx.doi.org/10.1007/s12032-021-01472-3DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7868320PMC
February 2021

Sacrificial Synthesis of Supported Ru Single Atoms and Clusters on N-doped Carbon Derived from Covalent Triazine Frameworks: A Charge Modulation Approach.

Adv Sci (Weinh) 2021 Feb 20;8(3):2001493. Epub 2020 Dec 20.

Chemical Sciences Division Oak Ridge National Laboratory Oak Ridge TN 37831 USA.

High-temperature pyrolysis of nitrogen (N)-rich, crystalline porous organic architectures in the presence of a metal precursor is an important chemical process in heterogeneous catalysis for the fabrication of highly porous N-carbon-supported metal catalysts. Herein, covalent triazine framework (CTF) and CTF-I (that is, CTF after charge modulation with iodomethane) are presented as sacrificial templates, for the synthesis of carbon-supported Ru catalysts-Ru-CTF-900 and Ru-CTF-I-900 respectively, following high-temperature pyrolysis at 900 °C under N atmosphere. Predictably, the dispersed Ru on pristine CTF carrier suffered severe sintering of the Ru nanoparticles (NPs) during heat treatment at 900 °C. However, the Ru-CTF-I-900 catalyst is composed of ultra-small Ru NPs and abundant Ru single atoms which may have resulted from much stronger Ru-N interactions. Through modification of the micro-environment within the CTF architecture, Ru precursor interacted on charged-modulated CTF framework shows electrostatic repulsion and steric hindrance, thus contributing toward the high density of single Ru atoms and even smaller Ru NPs after pyrolysis. A Ru-Ru coordination number of only 1.3 is observed in the novel Ru-CTF-I-900 catalyst, which exhibits significantly higher catalytic activity than Ru-CTF-900 for transfer hydrogenation of acetophenone.
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http://dx.doi.org/10.1002/advs.202001493DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7856886PMC
February 2021

Perovskite Oxide-Halide Solid Solutions: A Platform for Electrocatalysts.

Angew Chem Int Ed Engl 2021 Apr 18;60(18):9953-9958. Epub 2021 Mar 18.

Chemical Sciences Division, Oak Ridge National Laboratory, Oak Ridge, TN, 37831, USA.

The successful integration or hybridization of perovskite oxides with their halide cousins would enable the formation of both multi-anionic and multi-cationic solid solutions with unique metal-ion sites and synergistic properties that could potentially surpass the performance of classic perovskites. However, such solid solutions had not been produced previously owing to their distinct formation energies and different synthesis conditions. Solid solutions combining perovskite oxides with fluorides were produced in this study by mechanochemical synthesis. The obtained perovskite oxide-halide solid solutions had highly mixed elements and valences, uniform element distributions, and single-phase crystalline structures. The solid solution with an optimized combination of oxides and fluorides exhibited enhanced catalytic performance in the oxygen evolution reaction.
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http://dx.doi.org/10.1002/anie.202101120DOI Listing
April 2021
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