In this work, a protocol to synthesize monodisperse mesoporous silica microparticles via a unique microfluidic jet spray-drying route is reported for the first time. The microparticles demonstrated highly ordered hexagonal mesostructures with surface areas ranging from ~900 up to 1500m²/g and pore volumes from ~0.6 to 0.8cm³/g. The particle size could be easily controlled from ~50 to 100μm from the same diameter nozzle via changing the initial solute content, or changing the drying temperature. The ratio of the surfactant (CTAB) and silica (TEOS), and the amount of water in the precursor were found to affect the degree of ordering of mesopores by promoting either the self-assembly of the surfactant-silica micelles or the condensation of the silica as two competing processes in evaporation induced self-assembly. The drying rate and the curvature of particles also affected the self-assembly of the mesostructure. The particle mesostructure is not influenced by the inlet drying temperature in the range of 92-160°C, with even a relatively low temperature of 92°C producing highly ordered mesoporous microparticles. The spray-drying derived mesoporous silica microparticles, while of larger sizes and more rapidly synthesized, showed a comparable performance with the conventional mesoporous silica MCM-41 in controlled release of a dye, Rhodamine B, indicating that these spray dried microparticles could be used for the immobilisation and controlled release of small molecules.

Kathryn Waldron;铎 吴;Zhangxiong Wu;Wenjie Liu;Cordelia Selomulya;东元 赵;Xiao Dong Chen

Journal of Colloid and Interface Science

2014-3-15

The immobilization behavior of lysozyme (LYZ) in mesoporous silicas (MPSs) with controlled morphologies has been investigated. The effects of entrance amount (EA) on the quantity and rate of immobilization of enzymes have been investigated due to the successful morphological control of MPSs. EA increases with the decrease of particle size of MPSs, leading to a significant improvement of immobilization ability. Rod-like SBA-15 (∼1-2 μm in length) shows a faster adsorption rate and larger immobilization amount than that for conventional SBA-15 (∼20 μm in length). It is observed that the adsorption rate of enzyme within MPSs is independent of the initial enzyme concentration. Increasing temperature favors a fast immobilization process of LYZ into MPSs. A maximum equilibrium adsorption amount of LYZ into rod-like SBA-15 is ∼500 mg/g at all temperatures under study (455°C). However, for conventional SBA-15, this maximum equilibrium adsorption amount cannot be observed within 48 h even at high temperature. A strong interaction between LYZ and MPSs is observed, resulting in very small amount of LYZ released by MPSs. Such conclusions may be important to understand the mechanism of protein immobilization within MPSs and potentially useful for applications of MPSs in biocatalysts or biosensors.

Jie Lei;杰 范;承忠 余;Luyan Zhang;Shiyi Jiang;波 屠;东元 赵

Microporous and Mesoporous Materials

2004-9-6

Mesoporous core-shell composites with large-pore silica shells are highly desired for a broad spectrum of applications. We report an ultra-dilute liquid-phase coating strategy in an acidic medium for controllable synthesis of uniform micro/mesoporous core-shell composites zeolite@SBA-15 comprising zeolite cores and mesoporous silica SBA-15 shells using triblock compolymer Plunoric P123 as a template. Structural characterizations show that the core-shell composites possess tunable specific surface areas (115-228 m² g ^-1), large pores (∼7.0 nm in diameter) with plenty of mesotunnels (∼3.0 nm) from silica shells, original crystalline zeolite frameworks, and opened junctions between micropores and mesopores. The silica shells have ordered 2-D hexagonal mesopore channels, most of which are annularly parallel (fingerprint-like arrangement) to the anisotropic zeolite faces. The shell-thickness is crystal face-dependent, which could be facilely tuned in the range of 30-45 and 40-120 nm on a pinacoids/dome faces and b pinacoids of a zeolite single-crystal, respectively. Moreover, the synthesis parameters such as MgSO₄ additive, stirring rate, acidity, temperature and reaction time show great influences on the formation of uniform core-shell composites. Post-hydrothermal treatment at 100 °C has been for the first time adopted to improve mesostructural regularity of the core-shell composites. A scheme regarding surface-induced micellization and hydrothermal rearrangement of mesostructured silica shells in the coating process is proposed to illustrate the formation of core-shell composites. The core-shell composite HZSM-5@SBA-15 (HZ@S15) was employed as a catalyst for methanol to propylene (MTP) conversion, and shows excellent catalytic performance with high methanol conversion (∼98%) and propylene to ethylene (P/E) ratio (∼10.7) as well as propylene selectivity (∼39%).

Xufang Qian;Junming Du;Bin Li;Min Si;Yisu Yang;Yuanyuan Hu;Guoxing Niu;亚红 张;华龙 徐;波 屠;颐 唐;东元 赵

Chemical Science

2011-10

Transition metal phosphides (TMPs), as non-precious metal compounds, have attracted growing interest as heterogeneous electrocatalysts for overall water splitting. They have been studied as robust catalysts for hydrogen evolution reaction (HER) at a wide pH range. In particular, Fe, Co, Ni-based phosphides also showed high performance for oxygen evolution reaction (OER) in alkaline solutions. This review focuses on the strategies developed for preparing TMPs with enhanced HER or OER performance. These strategies include tuning the stoichiometric ratio of metal and phosphorous, hetero-atom doping or alloying, forming nano-carbon/TMPs hybrids and engineering special structures by modifying surface wettability, forming hetero-structure interfaces and generating porous structures. In terms of elemental doping strategy, the reported performance of Fe, Co, Ni-based alloying phosphides as bifunctional catalysts for both HER and OER are also summarized. Finally, the challenges and perspectives for TMPs in water splitting application are briefly discussed.

Yang Wang;Biao Kong;东元 赵;Huanting Wang;Cordelia Selomulya

Nano Today

2017-8

(Figure Presented) Ultrahigh stability (> 1400°C) is found for the highly ordered mesoporous polymers and carbon frameworks synthesized from polymerization of phenol and formaldehyde around triblock copolymer templates. Calcination and carbonization lead to removal of the templates and formation of hexagonal and cubic carbon mesostructures with large uniform pores and surface areas (see schematic diagram).

Yan Meng;Dong Gu;Fuqiang Zhang;益峰 施;Haifeng Yang;Zheng Li;承忠 余;波 屠;东元 赵

Angewandte Chemie - International Edition

2005-11-3

In the early 1990s, Mobil scientists and Japanese scientists separately reported the synthesis of mesostructured silicates that possess large uniform pore sizes (1.5-10 nm) high ordered nanochannels, large surface areas (∼ 1500 cu m/g) and attractive liquid crystal structures. These characteristics offer mesoporous molecular sieves good opportunities in hydrogen storage, catalysis, etc. A discussion covers the surfactant-templating approach for the synthesis of ordered mesoporous molecular sieves; synthesis pathways; corresponding mechanisms; key factors for the synthesis including the selection of surfactants, hydrothermal method, EISA strategy, the control of mesostructures, and the adjustment of pore sizes and morphologies; and applications of mesoporous materials.

东元 赵;Ying Wan

2007

A new procedure for the synthesis of mesoporous silica spheres with controlled particle size (9.0-17.6 μm) and pore size (2.3-4.8 nm) was developed. It was based on the hydrothermal syntheses by mixing nonionic surfactant EO₂₀PO₃₀EO₂₀ (P65) and TEOS under static acidic conditions. The size of spheres was controlled by adjusting the synthesis temperature, the synthesis time, and the amount of added KCl. The pore size of the spheres was controlled by adding the 1,3,5-trimethylbenzene (TMB) or changing the hydrothermal temperature and characterized by nitrogen adsorption-desorption analysis, whereas the size of the spheres was analyzed by scanning electron microscopy (SEM) and further confirmed by the laser scattering particle size distribution analyzer. The bio-immobilization ability of such mesoporous silica spheres was characterized by protein adsorption analysis. Mesoporous silica spheres with the largest pore size (4.8 nm) among all materials under investigation showed the highest specific immobilization amount of lysozyme (192 mg/g), while the spheres with smaller pore size (≤4.3 nm) have markedly low immobilization amount (≤42 mg/g). These mesoporous silica spheres with diameter ∼10 μm in size may be readily used as a good substrate in high performance liquid chromatography (HPLC).

Jie Lei;承忠 余;杰 范;Yan Yan;波 屠;东元 赵

Acta Chimica Sinica

2005

We report the synthesis of novel polysilsesquioxane hybrid crystals prepared from two precursors with hexylene- and octylene-bridged groups. Both crystals are composed of bimolecular rings (18- and 22-membered, respectively) formed by one-step condensation of two hydrolyzed monomers. The hydrogen bonds between silanol groups and the weak van der Waal's interactions between alkyl chains link the large rings as building blocks together into self-assembled, three-dimensional molecular crystalline structures. The precise control of the sol-gel process is considered to be the crucial factor in fabricating flexible long alkyl chains into an ordered stacking. These contributions extend the understanding of the sol-gel chemistry of polysilses-quioxanes.

Xufeng Zhou;Sui Yang;承忠 余;Zhenhua Li;Xiaoxia Yan;勇 曹;东元 赵

Chemistry - A European Journal

2006-11-15

A series of Pd/Fe ₂ O ₃ nanohybrids with low metal content supported with Amberlite resin formate (Pd/Fe ₂ O ₃ @ARF) was prepared and characterized by FTIR, XRD, XPS, EELS, SEM-EDAX, and HRTEM. The coexistence of mainly crystalline Pd and Fe ₂ O ₃ nanoparticles (NPs) of average size ∼4-5 nm in the resin matrix was confirmed. These nanohybrids were used for hydrodehalogenation of polyhaloaromatics using NaBH ₄ as a reducing agent in water. Notably, the composite Pd/Fe ₂ O ₃ @ARF-110 exhibits excellent catalytic performance in the hydrodehalogenation of different haloaromatics. High TOF (in comparison to other related heterogeneous catalysts), recyclability, and chemoselectivity between halide and C=C bond make this nanohybrid catalyst very attractive for the degradation of persistent organic pollutants originated from industries. The experimental observations and other analytical studies suggest that the enhanced catalytic activity could be due to strong interactions between Fe ₂ O ₃ and Pd NPs that facilitate the cleavage of B-H bond and subsequent hydride generation.

Kinkar Biswas;Shreyasi Chattopadhyay;Yunke Jing;仁超 车;Goutam De;Basudeb Basu;东元 赵

Industrial & Engineering Chemistry Research

2019-2-13

Bo Zhu;Bin Li;Linda Zou;Anita J. Hill;东元 赵;跃生 林;Mikel Duke

2013-2-13