One-pot synthesis of vanadium-containing silica SBA-3 materials and their catalytic activity for propene oxidation

V-containing silica SBA-3 mesoporous catalysts were prepared by means of one-pot hydrothermal procedure with NH₄VO₃ or VOSO₄ as vanadium precursors under various acidic medium of the reaction mixture (pH < 1, 2.2 or 3.1). The combined spectral techniques (DR UV-vis, FTIR, EPR) as well H₂-TPR allowed to determine the nature of vanadium species in the studied samples. A successful incorporation of vanadium into the structure of silica SBA-3 was attained for the samples with low V content (<1 wt%), whereas the V-rich samples (i.e. >5 wt%) exhibited the presence of isolated vanadium and also of polynuclear surface species. The resulting V-bearing samples contain the Brønsted and Lewis acidic centres evidenced by FTIR spectra of adsorbed pyridine and by catalytic activity for 2-propanol decomposition and cumene cracking. Ammonia TPD allowed to estimate the number and strength of acid sites in regards to the vanadium content. Propene oxidation with N₂O revealed noticeable activity of the synthesised V-SBA-3 samples in epoxidation reaction. On the basis of TOF analysis indicating the activity of particular vanadium ions it seems that not all of the introduced V atoms take part in the formation of mild electrophilic oxygen species responsible for propene oxide formation.

Efficient SBA-3 vanadosilicate catalysts for propene oxidation obtained for the first time by the one-pot synthesis.     

3D mesoporous structure assembled from monoclinic M-phase VO2 nanoflakes with enhanced thermochromic performance

Monoclinic M-phase VO₂ is a promising candidate for thermochromic materials due to its abrupt change in the near infrared (NIR) transmittance along with the metal-to-insulator transition (MIT) at a critical temperature ∼68 °C. However, low luminous transmittance (T_lum), poor solar energy modulation ability (ΔT_sol), and high phase transition temperature (T_c) can limit the application of VO₂ for smart windows. To overcome these limitations, 3D mesoporous structure can be employed in VO₂ films. Herein, 3D mesoporous structures assembled from monoclinic M-phase VO₂ nanoflakes with a pore size of about 2–10 nm were synthesized by a hydrothermal method using Ensete ventricosum fiber (EF) as a template followed by calcination at 450 °C. The prepared film exhibited excellent thermochromic performance with balanced T_lum = 67.3%, ΔT_sol = 12.5%, and lowering T_c to 63.15 °C. This is because the 3D mesoporous structure can offer the uniform dispersion of VO₂ nanoflakes in the film to enhance T_lum, ensure sufficient VO₂ nanoflakes in the film for high ΔT_sol and lower T_c. Therefore, this work can provide a green approach to synthesize 3D mesoporous structures assembled from monoclinic M-phase VO₂ nanoflakes and promote their application in smart windows.

Herein, 3D mesoporous structures assembled from monoclinic M-phase VO₂ nanoflakes were successfully synthesized for enhanced thermochromic performance.     

Effects of mesoporous silica particle size and pore structure on the performance of polymer-mesoporous silica mixed matrix membranes

The fabrication of mixed matrix membranes (MMMs) has been regarded as an effective and economic approach to enhance the gas permeability and selectivity properties of conventional polymeric membranes for gas separation applications. However, the poor compatibility between polymeric matrix and inorganic filler in MMMs could lead to the generation of interfacial defects resulting in reduced gas selectivity. In this work, with the aim of studying the effect of particle size and pore structure of the filler on the performance of the resultant MMMs, nano/micro sized spherical mesoporous silicas with 2D/3D pore structure (MCM-41 and MCM-48) were synthesized and selected as fillers for the preparation of polydimethylsiloxane (PDMS)-based MMMs. The separation properties of the membranes prepared were characterized by permeability measurements for nitrogen and organic vapors (C₃H₆ and n-C₄H₁₀). Compared with microsized particles, nanosized fillers have better dispersion in the polymer matrix which could minimize the formation of non-selective microvoids around the particles, leading to higher vapor/N₂ ideal selectivities of the MMMs, even at the high loading (15 wt%). Moreover, due to the conventional random packing orientation of the particles in the polymer, vapor permeation was severely hindered in the MMMs fabricated from mesoporous silica with 2D pore channels. The interface morphologies and gas diffusion paths in the MMMs have also been proposed. With an optimum loading of nanosized MCM-48 (3D pore structure), the vapor permeabilities and vapor/N₂ ideal selectivities of the MMMs were shown to increase simultaneously, compared with the neat polymer membrane.

The effects of filler particle size and pore structure on the gas separation performance of mixed matrix membranes were comprehensively investigated via elaborate synthesis of mesoporous silicas.     

Molybdenum(0) tricarbonyl and tetracarbonyl complexes with a cationic pyrazolylpyridine ligand: synthesis,crystal structures and catalytic performance in olefin epoxidation

The synthesis of molybdenum(0) tricarbonyl and tetracarbonyl complexes of the form [Mo(CO)₃(ptapzpy)Br] (1) and cis-[Mo(CO)₄(ptapzpy)]Br (2) is reported, where ptapzpy = 2-(1-propyltrimethylammonium-3-pyrazolyl)pyridine. Preparation of these derivatives was accomplished either through thermal replacement of CO in Mo(CO)₆ (for 1) or substitution under milder conditions of piperidine ligands in the precursor cis-[Mo(CO)₄(pip)₂] (for 2). The crystal structures of the ligand [ptapzpy]Br and complexes 1 and 2 were determined. Thermal treatment of 2 at 125–150 °C leads to mono decarbonylation and formation of 1. On the other hand, oxidative decarbonylation of 1 and 2 by reaction with tert-butylhydroperoxide (TBHP, 10 equiv.) gives a molybdenum oxide hybrid material formulated as [Mo₃O₉([ptapzpy]Br)₂]·nH₂O (3), which was characterised by FT-IR and Raman spectroscopy, thermogravimetric analysis, and ¹³C{¹H} CP MAS NMR spectroscopy. Compounds 1–3 were effective (pre)catalysts for the epoxidation of cis-cyclooctene at 55 °C with aqueous H₂O₂ or TBHP (slightly better results were obtained with the former). The characterisation of the Mo-containing solids isolated after the catalytic reaction showed that poorly soluble β-octamolybdate salts, (L)_x[Mo₈O₂₆], were formed from 1–3 with TBHP and from 1 with H₂O₂, while soluble oxoperoxo species were formed from 3 with H₂O₂. These findings helped to explain the different catalytic performances obtained.

The oxidative decarbonylation and catalytic chemistry of molybdenum(0) tricarbonyl and tetracarbonyl complexes containing the same diimine ligand are compared.     

Pt incorporated mesoporous carbon spheres: controllable structure with enhanced catalytic activity and stability

We report a simple synthesis process to prepare well-dispersed Pt nanoparticles incorporated in mesoporous carbon spheres. By manipulating the relative ratio of Pt precursor and resorcinol-formaldehyde resin (RF), Pt/carbon composites with different morphologies and Pt content were achieved. The as-prepared Pt/C composite materials show higher catalytic activity and reusability for the reduction of 4-nitrophenol (4-NP) than the Pt deposited commercial activated carbon (Pt/AC), which can be ascribed to the high dispersion of Pt nanoparticles in the carbon spheres.

We report a simple synthesis process to prepare well-dispersed Pt nanoparticles incorporated in mesoporous carbon spheres.     

Two 3D Mn-based coordination polymers: synthesis,structure and magnetocaloric effect

Two three-dimensional (3D) coordination polymers, namely Mn^II₆(CH₃COO)₂(HCOO)₂(IN)₈(C₄H₈O)₂(H₂O) and Mn^III₆Mn^II₁₂(μ₃-O)₆(CH₃COO)₁₂(IN)₁₈(H₂O)_7.5 (abbreviated as Mn^II₆ and Mn^II₁₂Mn^III₆ respectively; HIN = isonicotinic acid), were synthesized by the reaction of Mn(CH₃COO)₂·4H₂O and isonicotinic acid under solvothermal conditions. Magnetic studies revealed that antiferromagnetic interactions may be present in compounds Mn^II₆ and Mn^II₁₂Mn^III₆. Moreover, the values of −ΔS_m (26.27 (Mn^II₆) and 37.69 (Mn^II₁₂Mn^III₆) J kg⁻¹ K⁻¹ at ΔH = 7 T) are relatively larger than those of the reported Mn-based coordination polymers. This work provides a great scope in the magnetocaloric effect (MCE) of pure 3d-type systems.

Two 3D coordination polymers (Mn^II₆ and Mn^II₁₂Mn^III₆) were synthesized. Magnetic studies revealed that they are potential magnetic materials.     

Novel mesoporous Ag@SiO2 nanospheres as a heterogeneous catalyst with superior catalytic performance for hydrogenation of aromatic nitro compounds

Mesoporous core–shell structure Ag@SiO₂ nanospheres are constructed to prevent Ag nanoparticles from aggregation during the hydrogenation reaction. The prepared catalyst shows superior catalytic performance for hydrogenation of nitro compounds with 100% conversion and selectivity without any by-products, which also indicates good recycling performance for several times use.

Mesoporous core–shell structure Ag@SiO₂ nanospheres are constructed to prevent Ag nanoparticles from aggregation during the hydrogenation reaction.     

介孔硅纳米粒超声影像及治疗研究进展

介孔硅纳米粒热/化学稳定性强,比表面积大,表面易于修饰,可改善其性能并赋予新的功能。且介孔硅纳米粒的粒径、形貌、结构等可控,在医学领域引起广泛关注。本文对介孔硅纳米粒在超声影像和超声治疗方面的研究进展进行综述。     

ATRP-based synthesis of a pH-sensitive amphiphilic block polymer and its self-assembled micelles with hollow mesoporous silica as DOX carriers for controlled drug release

The atom transfer radical polymerization (ATRP)-based synthesis of a pH-sensitive fluorescent polymer (PSDMA-b-POEGMA) was successfully prepared using 3,6-dibromo-isobutyramide acridine (DIA), an initiator with a fluorescent chromophore, to initiate a lipophilic monomer 2-styryl-1,3-dioxan-5-yl methacrylate (SDMA) and a hydrophilic monomer oligo(ethylene glycol) methyl ether (OEGMA), which contained a cinnamic aldehyde acetal structure. With the addition of hollow mesoporous silicon (HMS@C18), the pH-sensitive core–shell nanoparticles (HMS@C18@PSDMA-b-POEGMA) were developed via a self-assembly process as carriers for the anticancer drug doxorubicin (DOX) for drug loading and controlled release. The nanocomposites showed a higher drug loading capacity which was much higher than that observed using common micelles. At the same time, the polymer coated on the surface of the nanoparticles contains the fluorescent segment of an initiator, which can be used for fluorescence contrast of the cells. The nanocomposite carrier selectively inhibits human melanoma cell A375 relative to human normal fibroblasts GM. The in vitro results suggested that a smart pH sensitive nanoparticles drug delivery system was successfully prepared for potential applications in cancer diagnosis and therapy.

A pH-sensitive core–shell nanoparticle (HMS@C18@PSDMA-b-POEGMA) was developed via a self-assembly process as the carrier of anticancer drug doxorubicin (DOX) for drug loading and controlled release.     

Hydrothermal-template synthesis and electrochemical properties of Co3O4/nitrogen-doped hemisphere-porous graphene composites with 3D heterogeneous structure

Despite the high capacity of Co₃O₄ employed in lithium-ion battery anodes, the reduced conductivity and grievous volume change of Co₃O₄ during long cycling of insertion/extraction of lithium-ions remain a challenge. Herein, an optimized nanocomposite, Co₃O₄/nitrogen-doped hemisphere-porous graphene composite (Co₃O₄/N-HPGC), is synthesized by a facile hydrothermal-template approach with polystyrene (PS) microspheres as a template. The characterization results demonstrate that Co₃O₄ nanoparticles are densely anchored onto graphene layers, nitrogen elements are successfully introduced by carbamide and the nanocomposites maintain the hemispherical porous structure. As an anode material for lithium-ion batteries, the composite material not only maintains a relatively high lithium storage capacity (the first discharge specific capacity can reach 2696 mA h g⁻¹), but also shows significantly improved rate performance (1188 mA h g⁻¹ at 0.1 A g⁻¹, 344 mA h g⁻¹ at 5 A g⁻¹) and enhanced cycling stability (683 mA h g⁻¹ after 500 cycles at 1 A g⁻¹). The enhanced electrochemical properties of Co₃O₄/N-HPGC nanocomposites can be ascribed to the synergistic effects of Co₃O₄ nanoparticles, novel hierarchical structure with hemisphere-pores and nitrogen-containing functional groups of the nanomaterials. Therefore, the developed strategy can be extended as a universal and scalable approach for integrating various metal oxides into graphene-based materials for energy storage and conversion applications.

The Co₃O₄/N-HPGC nanocomposites synthesized by a hydrothermal-template approach with polystyrene microspheres as the template possess excellent electrochemical performance.     

Rationally tailored redox ability of Sn/γ-Al2O3 with Ag for enhancing the selective catalytic reduction of NOx with propene

The development of excellent selective catalytic reduction (SCR) catalysts with hydrocarbons for lean-burn diesel engines is of great significance, and a range of novel catalysts loaded with Sn and Ag were studied in this work. It was found that the synergistic effects of Sn and Ag enabled the 1Sn5Ag/γ-Al₂O₃ (1 wt% Sn and 5wt% Ag) to exhibit superior C₃H₆-SCR performance. The de-NO_x efficiency was maintained above 80% between 336 and 448 °C. The characterization results showed that the presence of AgCl crystallites in the 1Sn5Ag/γ-Al₂O₃ catalyst helped its redox ability maintain an appropriate level, which suppressed the over-oxidation of C₃H₆. Besides, the number of surface adsorbed oxygen (O_α) and hydroxyl groups (O_γ) were enriched, and their reactivity was greatly enhanced due to the coexistence of Ag and Sn. The ratio of Ag⁰/Ag⁺ was increased to 3.68 due to the electron transfer effects, much higher than that of Ag/γ-Al₂O₃ (2.15). Lewis acid sites dominated the C₃H₆-SCR reaction over the 1Sn5Ag/γ-Al₂O₃ catalyst. The synergistic effects of Sn and Ag facilitated the formation of intermediates such as acetates, enolic species, and nitrates, and inhibited the deep oxidation of C₃H₆ into CO₂, and the C₃H₆-SCR mechanism was carefully proposed.

HC-SCR is a more attractive approach for removing NO_x from lean-burn diesel engines compared with NH₃-SCR. The novel SnAg/γ-Al₂O₃ catalyst exhibit excellent C₃H₆-SCR activity, due to the optimized redox ability and enriched hydroxyl groups.     

Fe2O3 and Gd2O3 nanoparticles loaded in mesoporous silica: insights into influence of NPs concentration and silica dimensionality

Fine Fe₂O₃ and Gd₂O₃ magnetic nanoparticles (NPs) with sizes 7 nm and 10 nm embedded into mesoporous silica have been prepared using a wet-impregnation method. A comparative study of the reactant concentration along with the hosting matrix symmetry on mesostructuring and the magnetic properties of the nanocomposites have been investigated. Reactants with four different concentrations of Fe³⁺ and Gd³⁺ ions and silica matrices with two different kinds of symmetry (hexagonal and cubic) have been utilized for the study. The structural characterization of the samples has been carried out by the N₂ adsorption/desorption method, high-energy X-ray diffraction (HE-XRD), TG/DTA, and high resolution transmission electron microscopy (HRTEM). The magnetic properties of the nanocomposites have been examined by means of SQUID magnetometry. It has been found that a range of different magnetic states (diamagnetic, paramagnetic, ferromagnetic, superparamagnetic) can be induced by the feasible tailoring of the particle concentration, the porous matrix symmetry and the composition. Furthermore, the existence of a “critical concentration limit” for embedding the particles within the body of the matrix has been confirmed. Exceeding the limit results in the expulsion of nanoparticles on the outer surface of the mesoporous matrix. Revelation of the relationships between particle concentration, matrix symmetry and magnetic properties of the particular composite reported in this study may facilitate the design and construction of advanced intelligent nanodevices.

The concentration of nanoparticles inside the pores and the symmetry of the porous matrix significantly affected the magnetic properties.     

Sandwich type polyoxometalates encapsulated into the mesoporous material: synthesis,characterization and catalytic application in the selective oxidation of sulfides

The A-type sandwich polyoxometalates of [(HOSn^IVOH)₃(PW₉O₃₄)₂]¹²⁻ (P₂W₁₈Sn₃) and [(OCe^IVO)₃(PW₉O₃₄)₂]¹²⁻ (P₂W₁₈Ce₃) were immobilized for the first time into the porous metal–organic framework MIL-101(Cr). FT-IR, powder X-ray diffraction, SEM-EDX, ICP analysis, N₂ adsorption and thermogravimetric analysis collectively confirmed immobilization and good distribution of polyoxometalates into cages of MIL-101(Cr). The catalytic activities of the homogeneous P₂W₁₈Sn₃ and P₂W₁₈Ce₃ and the corresponding heterogeneous catalysts were examined in the oxidation of sulfides to sulfones with H₂O₂ as the oxidant at room temperature. The effects of different dosages of polyoxometalates, type of solvent, reaction time, amount of catalyst and oxidant in this catalytic system were investigated. The new P₂W₁₈Sn₃@MIL-101 and P₂W₁₈Ce₃@MIL-101 nanocomposites exhibited good recyclability and reusability in at least five consecutive reaction cycles without significant loss of activity or selectivity.

The A-type sandwich POMs of [(HOSn^IVOH)₃(PW₉O₃₄)₂]^12– (P₂W₁₈Sn₃) and [(OCe^IVO)₃(PW₉O₃₄)₂]^12– (P₂W₁₈Ce₃) were immobilized for the first time into the porous MIL-101 MOF. Their catalytic activities were examined in the oxidation of sulfides to sulfones at room temperature.     

Multiscale design,interaction mechanism and performance of CL-20/Al energetic composites with embedded structure

In order to design and prepare hexanitrohexaazaisowurtzitane/aluminum (CL-20/Al) composites, the contact state of CL-20 with aluminum particles under different mixed solvent contents were calculated with the method of dissipative particle dynamics (DPD). Then the modified attachment energy (AE) model was applied to predict the morphologies of CL-20 in ethyl acetate, hexane and ethyl acetate/hexane mixed solvents. Furthermore, the morphologies, the surface element distribution, the sensitivity and the energy performance of CL-20/Al composites prepared with the solvent/non-solvent method were characterized, and the interaction mechanism were also obtained. The results achieved show that phase separation phenomenon becomes obvious with the decrease of ethyl acetate/n-hexane mixed solvent content. CL-20/aluminum particles will form the composites of aluminum particles embedded in CL-20 crystal when the solvent content is zero. The order of modified attachment energies for ethyl acetate/hexane mixed solvents on CL-20 faces is (011) > (110) > (101) ≈ (11−1) ≈ (10−1) > (002). Besides that, the crystalline morphology of CL-20 in acetate/hexane mixed solvents is spindle-shaped. There are many Al particles embedded in CL-20 crystals of CL-20/Al composites prepared by using solvent/non-solvent method. The calculated results agree well with the experimental results. In CL-20/Al composites, aluminum particles interact with CL-20 mainly through hydrogen bond and strong van der Waals force. The sensitivity of CL-20/Al composites decreased obviously compared with pure CL-20 and mechanical mixing composites. Besides, the CL-20/Al composites with embedded structure can increase the explosion reaction temperature to 791.2 K, which has obvious energy advantage compared with CL-20/Al physical mixture.

In order to design and prepare hexanitrohexaazaisowurtzitane/aluminum (CL-20/Al) composites, the contact state of CL-20 with aluminum particles under different mixed solvent contents were calculated with the method of dissipative particle dynamics (DPD).     

Preparation of sulfonated ordered mesoporous carbon catalyst and its catalytic performance for esterification of free fatty acids in waste cooking oils

Sulfonated ordered mesoporous carbon (SO₃H-OMC) solid acid catalysts from sucrose were prepared using hard-template method, and their catalytic performance as well as the deactivation mechanism for esterification of free fatty acids (FFAs) in waste cooking oils (WCOs) were evaluated. Effects of sulfonation time, sulfonation temperature and hard template structure type for the textural properties and acid properties of SO₃H-OMC were systematically investigated by N₂ adsorption–desorption, FT-IR, NH₃-TPD, TEM and strong acid density analysis. The results indicated that, SO₃H-OMC(s)-6-160 catalyst, which was prepared by using SBA-15 as hard template at sulfonation time of 6 h and sulfonation temperature of 160 °C, had well-ordered mesoporous structure and high –SO₃H groups density (2.32 mmol g⁻¹). Compared with SO₃H-APC-6-160 catalyst, cation-exchange resin D072 and SO₃H-OMC(k)-6-160 catalyst, it was found that the SO₃H-OMC(s)-6-160 catalyst exhibited highest activity (FFAs conversion was 93.8%) and good stability for the FFAs esterification, attributed to its 2D-hexagonal channels and hydrophobic surface. The –SO₃H groups being leached out of SO₃H-OMC catalysts into the liquid phase (especially methanol) would be the main reason causing catalyst deactivation.

Sulfonated ordered mesoporous carbon solid acid catalysts had excellent catalytic performance for esterification of methanol with FFAs in WCOs.     

Tetracycline catalytic photodegradation with mesoporous phosphated TiO2: characterization,process optimization and degradation pathway

Concern about the effect of tetracycline (TC) on the ecosystem has been increasing due to its endurance and low decomposition. Photocatalysts have attracted extensive interest as alternatives to other ordinary wastewater treatment methods. A nanosized mesoporous phosphated TiO₂ (P-TiO₂) photocatalyst was fabricated to degrade TC under Xe lamp irradiation. The TC degradation and COD removal rate reached 98.97% and 79.16% within 30 min. Photocatalysts were characterized by SEM, HRTEM, BET, DRS, XRD, XPS and FT-IR techniques. 31 experiments were designed to identify the best conditions for photocatalytic degradation of TC by response surface methodology (RSM) based on a central composite design (CCD). 6 key operating parameters were selected to study their interrelationships by CCD design. Based on the experimental data and ANOVA, the coefficient of determination (R²), the values of “Prob > F” and F-value were determined to be 0.9692, 0.002 and 7.87, respectively, which demonstrated that the model is significant. And the excellent correlation between the predicted and actual values also provided good confidence in the model. To achieve a higher removal rate of TC under appropriate and more economical experimental conditions, the optimum values of P-loading on TiO₂, concentration of P-TiO₂, irradiation time, photo intensity, pH and concentration of TC should be set to 17.45 wt%, 1.00 g L⁻¹, 40.39 min, 5 A, 7, 29.93 mg L⁻¹, respectively, in which the degradation of TC can reach 99.16%. Furthermore, the intermediates of TC verified by GC-MS analysis were mainly chains and rings. A possible pathway of photodegradation was also proposed.

The prepared P-TiO₂ has a perfect degradation effect on TC (99.16%) due to the loading of phosphate. The impact of multiple factors and the best degradation conditions were obtained by RSM. The possible degradation pathways of TC were proposed also.     

One-pot synthesis of biodegradable polydopamine-doped mesoporous silica nanocomposites (PMSNs) as pH-sensitive targeting drug nanocarriers for synergistic chemo-photothermal therapy

Nanomaterials have been widely used as drug carriers in the biomedical field. However, most of them have limited application because of their poor biocompatibility, targeting, and degradability. Therefore, exploring and developing novel drug nanocarriers to overcome these problems has widely attracted attention. In this study, polydopamine-doped mesoporous silica nanocomposites (PMSNs) were controllably synthesized by a one-pot oil-water biphase stratification approach. PMSNs showed good biodegradability in degradation experiments and also proved to have superior biocompatibility toward hepatocellular carcinoma cells (HepG2) compared with mesoporous silica nanoparticles (MSNs). And PMSNs loaded doxorubicin (DOX) (PMSNs@DOX) exhibited a pH-responsive release effect. Meanwhile, compared with PMSNs@DOX, folic acid-modified PMSNs@DOX (PMSNs@DOX@FA) displayed a targeted uptake and higher inhibition of HepG2 cells. Additionally, PMSNs@DOX@FA had excellent ability to kill tumor cells under synergistic chemo-photothermal therapy. Moreover, this synthetic strategy is promising for the fabrication of unique nanocomposites with various functional cores with PMSNs shells for diverse applications.

Polydopamine-doped mesoporous silica nanocomposites (PMSNs) were controllably synthesized by a one-pot approach. They were demonstrated to be good biodegradability, pH-responsive drug release and targeting synergistic chemo-photothermal therapy.