Xian Suo

Bio: Xian Suo is an academic researcher from University of Tennessee. The author has contributed to research in topics: Ionic liquid & Ionic bonding. The author has an hindex of 8, co-authored 25 publications receiving 220 citations. Previous affiliations of Xian Suo include Oak Ridge National Laboratory & Zhejiang University.

Transformation Strategy for Highly Crystalline Covalent Triazine Frameworks: From Staggered AB to Eclipsed AA Stacking.

Abstract: Fabrication of crystalline covalent triazine frameworks (CTFs) under mild conditions without introduction of carbonization is a long-term challenging subject. Herein, a tandem transformation strategy was demonstrated for the preparation of highly crystalline CTFs with high surface areas under mild and metal- and solvent-free conditions. CTF-1 with a staggered AB stacking order (orange powder) obtained in the presence of a catalytic amount of superacid at 250 °C was transformed to highly crystalline CTF-1 with an eclipsed AA stacking order (greenish powder) and surface area of 646 m2 g-1 through annealing at 350 °C under nitrogen. The strategy can be extended to the production of crystalline fluorinated CTFs with controllable fluorine content. This finding unlocks opportunities to design crystalline CTFs with tunable photoelectric properties.

Photoinduced Strong Metal-Support Interaction for Enhanced Catalysis.

Abstract: 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 TiOx overlayer, the presence of Ti3+ 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 Ti3+ species/oxygen vacancies (Ov) and then interfacial Pd-Ov-Ti3+ sites, affording a Pd/TiO2 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/TiO2.

Synthesis of anion-functionalized mesoporous poly(ionic liquid)s via a microphase separation-hypercrosslinking strategy: highly efficient adsorbents for bioactive molecules

Abstract: The synthesis of porous materials with a well-defined pore structure and functionality is centrally important for the development of advanced adsorbents and sensors. In this study, we explore a direct and facile methodology combining microphase separation and hypercrosslinking, and prepare anion-functionalized mesoporous poly(ionic liquid)s (MPILs) with well-developed mesopores. This methodology involved a copolymerization of IL monomers and crosslinkers to create mesopores via microphase separation. Additionally, the MPILs were texturally engineered by hypercrosslinking to stabilize/rebuild labile collapsed mesoporous networks and generate microporosity. Thus, a new family of anion-functionalized MPILs containing amphiphilic long-chain carboxylate ionic liquids (LCC-ILs) were synthesized. These anion-functionalized MPILs exhibited extraordinarily high adsorption capacity (211.45 mg g−1 for tocopherols) and excellent selectivity (Sδ/α, 8.65; Sβ&γ/α, 4.20) for bioactive tocopherol homologues and organic phenolic compounds with high structural similarity, significantly better than those of commercial adsorbents or common MPILs. Additionally, anion-functionalized MPILs demonstrated enhanced carbon dioxide (CO2) capture performances (28.18 mg g−1 at 0 °C and 1 bar). This study demonstrates the great potential of anion-functionalized MPILs as advanced adsorbents, and facilitates a textural engineering approach to the development of novel porous ionic materials for other applications.

Tailoring the Pore Size and Chemistry of Ionic Ultramicroporous Polymers for Trace Sulfur Dioxide Capture with High Capacity and Selectivity

Abstract: The efficient separation of trace sulfur dioxide (SO2 ) is challenging and industrially important, but limited number of adsorbents have been reported with both desired selectivity and high capacity at the low concentration of SO2 . Here we demonstrate the deep removal of SO2 with high uptake capacity (1.55 mmol g-1 ) and record SO2 /CO2 selectivity (>5000) at ultra-low pressure of 0.002 bar, using ionic ultramicroporous polymers (IUPs) with high density of basic anions. The successful construction of uniform ultramicropores via polymerizing ionic monomers into IUPs enables the fully exploitation of the selective anionic sites. Notably, the aperture size and surface chemistry of IUPs can be finely tuned by adjusting the branched structure of ionic monomers, which play critical roles in excluding CH 4 and N 2 , as well as reducing the coadsorption of CO2 . Further, the swelling property of IUPs with adsorption of SO2 contributed to the high SO2 uptake capacity and high separation selectivity. Systematic investigations including static gas adsorption, dynamic breakthrough experiments, stability tests and modeling studies confirmed the efficient performance of IUPs for trace SO2 capture.

A review on metal-organic frameworks: Synthesis and applications

Abstract: Metal organic frameworks (MOFs) are considered as a group of compounds, either metal ions or clusters, harmonized with organic ligands to form one or some dimensional structures. In addition to resilient bonds between inorganic and organic units, reticular synthesis creates MOFs, accurate selection of constituents of which can produce high thermal and chemical stability and crystals of ultrahigh porosity. Other solids have not shown the same accuracy normally used in chemical modification and even the capability of increasing their metrics with no modification of the underlying topology. With shape of building units and chemical compositions multiplying based on specific structures, MOFs might result in compounds that propose a synergistic mixture of features. This study presents up to date advances in both synthesis methods of MOFs and structural characteristics. Furthermore, the use of MOFs in different fields such as the removal of absorption and separation of toxic substances from gas and liquid, catalysts, a variety of sensors, storage of clean energies and environmental applications, medical and biological applications, and optoelectronic equipment is included.

Emerging trends in porous materials for CO2 capture and conversion

Abstract: The presence of an excessive concentration of CO2 in the atmosphere needs to be curbed with suitable measures including the reduction of CO2 emissions at stationary point sources such as power plants through carbon capture technologies and subsequent conversion of the captured CO2 into non-polluting clean fuels/chemicals using photo and/or electrocatalytic pathways. Porous materials have attracted much attention for carbon capture and in the recent past; they have witnessed significant advancements in their design and implementation for CO2 capture and conversion. In this context, the emerging trends in major porous adsorbents such as MOFs, zeolites, POPs, porous carbons, and mesoporous materials for CO2 capture and conversion are discussed. Their surface texture and chemistry, and the influence of various other features on their efficiency, selectivity, and recyclability for CO2 capture and conversion are explained and compared thoroughly. The scientific and technical advances on the material structure versus CO2 capture and conversion provide deep insights into designing effective porous materials. The review concludes with a summary, which compiles the key challenges in the field, current trends and critical challenges in the development of porous materials, and future research directions combined with possible solutions for realising the deployment of porous materials in CO2 capture and conversion.

Tailoring pore properties of MCM-48 silica for selective adsorption of CO2

Abstract: Four different types of amine-attached MCM-48 silicas were prepared and investigated for CO(2) separation from N(2). Monomeric and polymeric hindered and unhindered amines were attached to the pore surface of the MCM-48 silica and characterized with respect to their CO(2) sorption properties. The pore structures and amino group content in these modified silicas were investigated by XRD, FT-IR, TGA, N(2) adsorption/desorption at 77 K and CHN/Si analysis, which confirmed that in all cases the amino groups were attached to the pore surface of MCM-48 at 1.5-5.2 mmol/g. The N(2) adsorption/desorption analysis showed a considerable decrease of the pore volume and surface area for the MCM-48 silica containing a polymeric amine (e.g., polyethyleneimine). The CO(2) adsorption rates and capacities of the amine-attached MCM-48 samples were studied employing a sorption microbalance. The results obtained indicated that in addition to the concentration of surface-attached amino groups, specific interactions between CO(2) and the surface amino groups, and the resultant pore structure after amine group attachment have a significant impact on CO(2) adsorption properties of these promising adsorbent materials.

Microstructural and Dynamical Heterogeneities in Ionic Liquids.

Abstract: Ionic liquids (ILs) are a special category of molten salts solely composed of ions with varied molecular symmetry and charge delocalization. The versatility in combining varied cation-anion moieties and in functionalizing ions with different atoms and molecular groups contributes to their peculiar interactions ranging from weak isotropic associations to strong, specific, and anisotropic forces. A delicate interplay among intra- and intermolecular interactions facilitates the formation of heterogeneous microstructures and liquid morphologies, which further contributes to their striking dynamical properties. Microstructural and dynamical heterogeneities of ILs lead to their multifaceted properties described by an inherent designer feature, which makes ILs important candidates for novel solvents, electrolytes, and functional materials in academia and industrial applications. Due to a massive number of combinations of ion pairs with ion species having distinct molecular structures and IL mixtures containing varied molecular solvents, a comprehensive understanding of their hierarchical structural and dynamical quantities is of great significance for a rational selection of ILs with appropriate properties and thereafter advancing their macroscopic functionalities in applications. In this review, we comprehensively trace recent advances in understanding delicate interplay of strong and weak interactions that underpin their complex phase behaviors with a particular emphasis on understanding heterogeneous microstructures and dynamics of ILs in bulk liquids, in mixtures with cosolvents, and in interfacial regions.