磺酸功能化介孔材料的合成及催化性能研究

使用1,2-二(三甲氧基甲硅烷基)乙烷和正硅酸甲酯两种硅脂分别与3-巯丙基三乙氧基硅烷共缩聚,合成出巯基修饰的含有乙烷桥键的硅基介孔材料(BM-n)以及巯基修饰的纯硅基介孔材料(TM-n),并用浓硝酸将其氧化,顺利的把修饰的巯基官能团氧化成磺酸基团(-SO3H)。使用SEM、TEM、小角度XRD和N2吸附脱附仪、FT-IR、元素分析、固体13 C-NMR等多种手段对其进行了表征。把得到的材料作为固体酸催化剂,催化丙酸与乙醇的酯化反应。结果表明骨架疏水性更强的乙烷桥键介孔硅基磺酸材料表现出更高的催化活性。

Preparation of three-dimensional interconnected mesoporous anatase TiO_2-SiO_2 nanocomposites with high photocatalytic activities

In this article, we report the preparation of a three-dimensional（3D） interconnected mesoporous anatase TiO2-SiO2 nanocomposite. The nanocomposite was obtained by using an ordered two-dimensional（2D） hexagonal mesoporous anatase 70 TiO2-30 SiO2-950 nanocomposite（crystallized at 950 °C for 2 h） as a precursor, NaO H as an etchant of SiO2 via a ＂creating mesopores in the pore walls＂ approach. Our strategy adopts mild conditions of creating pores such as diluted NaO H solution, appropriate temperature and solid/liquid ratio, etc. aiming at ensuring the integrities of mesopores architecture and anatase nanocrystals. XRD, TEM and N2 sorption techniques have been used to systematically investigate the physico-chemical properties of the nanocomposites. The results show that the intrawall mesopores are highly dense and uniform（average pore size 3.6 nm）, and highly link the initial mesochannels in a 3D manner while retaining mesostructural integrity. There is no significant change to either crystallinity or size of the anatase nanocrystals before and after creating the intrawall mesopores. The photocatalytic degradation rates of rhodamine B（RhB, 0.303 min^–1） and methylene blue（MB, 0.757 min^–1） dyes on the resultant nanocomposite are very high, which are 5.1 and 5.3 times that of the precursor; even up to 16.5 and 24.1 times that of Degussa P25 photocatalyst, respectively. These results clearly demonstrate that the 3D interconnected mesopores structure plays an overwhelming role to the increments of activities. The 3D mesoporous anatase TiO2-SiO2 nanocomposite exhibits unexpected-high degradation activities to RhB and MB in the mesoporous metal oxide-based materials reported so far. Additionally, the nanocomposite is considerably stable and reusable. We believe that this method would pave the way for the preparation of other 3D highly interconnected mesoporous metal oxide-based materials with ultra-high performance.

Defect engineered 2D mesoporous Mo-Co-O nanosheets with crystalline-amorphous composite structure for efficient oxygen evolution

Two-dimensional(2D)mesoporous metal-oxide(hydroxide)nanomaterials with defects are promising towards the realization of efficient electrocatalysis.Herein,we report a facile and effective one-pot solvothermal route to synthesize mesoporous Mo_(x)-Co-O hybrid nanosheets(NSs)which is composed of crystalline Mo_(4)O_(11) and amorphous cobalt hydroxide.Due to the corrosion of 1-octylamine at high temperatures,abundant mesoporous holes are created in situ over the Mo_(x)-Co-O hybrid NSs during the solvothermal process,which is beneficial to increasing the electrochemical surface area.The dimension of the Mox-Co-O NSs,size of mesoporous and the concentration of defects can be easily modulated by controlling the molar ratio of Mo/Co.Electrochemical measurements reveal that the 2D mesoporous Mo_(x)-Co-O NSs show an excellent activity for the oxygen evolution reaction with the highest catalytic activity of η_(10)=276 mV at 10 mA cm^(−2)in 1 mol L^(−1)KOH.Enhanced adsorption of intermediates and abundant oxygen vacancies achieved by appropriate Mo doping are the two main factors that contribute to the excellent catalytic activity of Mo_(0.2)-Co-O NSs.This work,with the construction of 2D metal-oxide(hydroxide)crystallineamorphous nanomaterials possessing abundant holes,oxygen vacancies and enhanced adsorption of intermediates,provides important insight on the design of more efficient catalysts.

An indicator-guided photo-controlled drug delivery system based on mesoporous silica/gold nanocomposites

A mesoporous silica/gold （MSN/Au） nanocomposite was designed for photo- controlled drug delivery targeted specifically at tumor cells. The MSN/Au nanocomposite was composed of MSN-based drug carriers and gold nanoparticle （AuNP）-based indicators. While the MSN-based drug carrier was a mesoporous silica nanoparticle immobilized with photo-switchable azobenzene （Azo） moieties, the AuNP-based indicator was a fluorescence-quenched AuNP modified with a matrix metalloproteinase （MMP） substrate and poly（ethylene glycol）. The two kinds of nanoparticles were connected by an α,β cyclodextrin （α,β CD） dimer ＂bridge.＂ In vitro studies demonstrated that the nanocomposite specifically interacted with tumor sites overexpressing MMP-2, which enabled guidance of the subsequent UV light irradiation for releasing entrapped drugs. Through integration of the AuNP-based indicator and the MSN-based drug carrier, the MSN/Au nanocomposite could precisely localize the released drug to tumor sites, thereby significantly improving therapeutic efficacy.

Controlling synthesis and gas-sensing properties of ordered mesoporous In2O3-reduced graphene oxide(r GO) nanocomposite

Herein, we describe a strategy for fabricating ordered mesoporous In2O3-reduced graphene oxide(r GO)nanocomposite through ultrasonic mixing, where ordered mesoporous In2O3 nanoparticles are synthesized via the nanocasting route by using mesoporous silica as a hard template, which possess ordered mesostructure with a large surface area of 81 m2g-1, and r GO nanosheets are synthesized from graphite via graphene oxide(GO) as intermediate. After coupled with r GO, mesoporous In2O3 could maintain its ordered mesostructure. We subsequently investigate the gas-sensing properties of all the In2O3 specimens with or without r GO for different gases. The results exhibit the ordered mesoporous In2O3-r GO nanocomposite possesses significantly enhanced response to ethanol even at low concentration levels, superior over pure mesoporous In2O3 nanoparticles. Similar strategy could be extended to other ordered mesoporous metal oxide–r GO nanocomposite for improving the gas-sensing property.

Synthesis, Characterization, and Catalytic Application of Highly Ordered Mesoporous Alumina-Carbon Nanocomposites

Highly ordered mesoporous carbon-alumina nanocomposites （OMCA） have been synthesized for the first time by a multi-component co-assembly method followed by pyrolysis at high temperatures. In this synthesis, resol phenol-formaldehyde resin （PF resin） and alumina sol were respectively used as the carbon and alumina precursors and triblock copolymer Pluronic F127 as the template. N2-adsorption measurements, X-ray diffraction, and transmission electron microscopy revealed that, with an increase of the alumina content in the nanocomposite from 11 to 48 wt.%, the pore size increased from 2.9 to 5.0 nm while the ordered mesoporous structure was retained. Further increasing the alumina content to 53 wt.% resulted in wormhole-like structures, although the pore size distribution was still narrow. The nanocomposite walls are composed of continuous carbon and amorphous alumina, which allows the ordered mesostructure to be well preserved even after the removal of alumina by HF etching or the removal of carbon by calcination in air. The OMCA nanocomposites exhibited good thermostability below 1000℃; at higher temperatures the ordered mesostructure partially collapsed, associated with a phase transformation from amorphous alumina into γ-Al2O3. OMCA-supported Pt catalysts exhibited excellent performance in the one-pot transformation of cellulose into hexitols thanks to the unique surface properties of the nanocomposite.