Pd/Ce-HMS介孔材料的结构和表面化学态

为了制备新型负载型Pd催化剂,采用合成后组装法和浸渍法室温合成了Pd/Ce-HMS介孔材料,产物用XRD、N2吸附、FTIR及XPS谱等手段进行表征。结果表明,Ce、Pd引入后六方介孔结构仍保持完好。产物的BET表面积为742.9m2.g-1,孔容0.803cm3.g-1,表面Pd、Ce物种主要以PdO2和CeO2形式存在。研究表明,Ce前驱体通过与孔表面富集的Si—OH基团作用而嵌入骨架或键合于孔表面,Pd担载时由于模板剂仍留在孔道中,因而没有造成孔道堵塞。

合成γ-丁内酯Cu-Zn-Al-O催化剂表面化学态研究

采用ＸＲＤ、ＸＰＳ和ＸＡＥＳ、ＥＳＲ等技术研究１，４丁二醇液相脱氢环化合成γ－丁内酯ＣｕＺｎＡｌＯ催化剂在不同条件下的表面化学态。结果表明：ＣｕＺｎＡｌＯ催化剂前驱体以Ｃｕ＋２形式存在；活化态、反应态表面只是Ｃｕ０，未测出Ｃｕ＋、Ｃｕ２＋；体相中尚存在部分未还原的Ｃｕ＋２；Ｃｕ０微晶有聚集的现象；关联活性测试结果认为：在活化态、反应态中ＺｎＯ、Ａｌ元素与Ｃｕ０的相互作用，可抑制微晶Ｃｕ０的聚集。

用XPS进行镉的表面化学态研究

用ＸＰＳ研究了多晶纯镉置于空气中形成的表面化学态。结果表明，Ｃｄ表面上除有大量吸附碳、氧外，还形成了ＣｄＯ和Ｃｄ（ＯＨ）２。Ｏ１ｓ谱的最佳曲线拟合表明有三个Ｏ１ｓ分量存在，其结合能分别为５３２．７ｅＶ，５２９．６ｅＶ，５３１．３ｅＶ。他们分别是吸附氧，ＣｄＯ和Ｃｄ（ＯＨ）２中Ｏ１ｓ的特征。本文推断Ｃｄ先与Ｏ２反应生成ＣｄＯ，再在水汽作用下形成Ｃｄ（ＯＨ）２，表面形成的ＣｄＯ和Ｃｄ（ＯＨ）２薄层阻挡了Ｏ２进一步与Ｃｄ起反应；而水汽继续与ＣｄＯ反应形成Ｃｄ（ＯＨ）２。置于空气中两个月的Ｃｄ表面上形成的ＣｄＯ和Ｃｄ（ＯＨ）２的百分含量分别为９．２％和８２．２％．还有Ｃｄ８．６％。镉表面化学态，Ｘ射线光电子能谱。

Physical, chemical, and surface charge properties of bauxite residue derived from a combined process

A detailed understanding of the composition,buffering capacity,surface charge property,and metals leaching behavior of bauxite residue is the key to improved management,both in reducing the environmental impact and using the material as an industrial by-product for other applications.In this study,physical,chemical,and surface charge properties of bauxite residue derived from a combined process were investigated.Results indicated that the main alkaline solids in bauxite residue were katoite,sodalite,and calcite.These minerals also lead to a higher acid neutralizing capacity of bauxite residue.Acid neutralizing capacity(ANC)to pH 7.0 of this residue is about 0.9 mol H^+/kg solid.Meanwhile,the Fe-,Al-,and Si-containing minerals in bauxite residue resulted in an active surface;The isoelectric point(IEP)and point of zero charge(PZC)were 7.88 and 7.65,respectively.This also leads to a fact that most of the metals in bauxite residue were adsorbed by these surface charged solids,which makes the metals not readily move under natural or even moderately acidic conditions.The leaching behavior of metals as a function of pH indicated that the metals in bauxite residue present low release concentrations(pH>3).

Mechanism of slope failure in loess terrains during spring thawing

Slope failure in loess terrains of Northern China during spring thawing period is closely related to the freeze-thaw cycling that surface soils inevitably experienced. Field surveys were carried out on natural and artificial slopes in thirteen surveying sites located in the Northern Shaanxi, the center of Loess Plateau, covering five characteristic topographic features including tablelands, ridges, hills, gullies and valleys. Based on the scale that is involved in freeze-thaw cycling, the induced failures can be classified into three main modes, i.e., erosion, peeling and thaw collapse, depending on both high porosity and loose cementation of loess that is easily affected. Model tests on loess slopes with gradients of 53.1°, 45.0° and 33.7° were carried out to reveal the heat transfer, water migration and deformation during slope failure. The surface morphology of slopes was photographed, with flake shaped erosion and cracks noted. For three slope models, time histories for the thermal regime exhibit three obvious cycles of freeze and thaw andthe maximum frost depth develops downwards as freeze-thaw cycling proceeds. Soil water in the unfrozen domain beneath was migrated towards the slope surface, as can be noticed from the considerable change in the unfrozen water content, almost synchronous with the variation of temperature. The displacement in both vertical and horizontal directions varies over time and three obvious cycles can be traced. The residual displacement for each cycle tends to grow and the slopes with higher gradients are more sensitive to potentially sliding during freeze-thaw cycling.

Rice Husk Ash:A New Silicon Source for Preparing SAPO-34 Catalysts Used in the Methanol-to-Olefins Reaction

SAPO-34 molecular sieves were synthesized directly by hydrothermal method with rice husk ash(RHA)used as the silicon source.The crystal structure,composition,surface morphology and acidity of the synthesized products weresieves had a high crystallinity,without any impure phase.Compared with the SAPO-34 prepared by the silica sol,RHA-SAPO-34 had similar acid properties in strength.The methanol to olefins(MTO)experiments showed that the SAPO-34molecular sieve synthesized from RHA exhibited both a good catalytic activity and ethylene selectivity.

Characterization of carbon fibers recovered through mechanochemical-enhanced recycling of waste carbon fiber reinforced plastics

In this study,we present the characterization of the carbon fibers recovered from the mechanochemical-enhanced recycling of carbon fiber reinforced fibers.The objectives of the study were to investigate the effect of our modified recycling method on the interfacial properties of recovered fibers.The reinforced plastics were recycled;the recycling efficiency was determined and the recovered fibers were sized using 1 wt%and 3 wt%concentration of(3-aminopropyl)triethoxysilane.We characterized the morphologies utilizing the electron spectroscopy for chemical analysis(ESCA),atomic force microscopy(AFM),FTIR-attenuated total reflection(ATR)spectroscopy and scanning electron microscopy(SEM).Although the surface of the fibers had no cracks,there was evidence of contaminations which affected the interfacial properties and the quality of the fibers.Results showed that the trends in the recovered and virgin fibers were similar with an increase in sizing concentration.The results highlighted the perspectives of increasing the quality of recovered fibers after the recycling process.

Inflnence of PH on Chemical Forms of Phosphate Ad－sorbed on Goethite Snrfaces

Chemical forms of the phosphate adsorbed on goethite surfaces and characteristics of the coordinategroups which exchange with P on goethite surfaces in solutions with different pll values were investigated.Results showed that the chemical forms of P on goethite surfaces changed from the dominance of monodentatecorrdination to that of bidentate one with increasing pH of the solution. By influencing types of phosphateions in solutions, pH affected the chemical forms of P on goethite surfaces. The amount of OH￣- displacedby phosphate on goethite surfaces was the most at pH 7.0, the second at pH 9.0, and the least at pH 4.5.

Synthesis of ordered mesoporous manganese titanium composite oxide catalyst for catalytic ozonation

In this account,highly ordered mesoporous MnO_x/TiO_2composite catalysts with efficient catalytic ozonation of phenol degradation were synthesized by the sol–gel method.The surface morphology and properties of the catalysts were characterized by several analytical methods,including SEM,TEM,BET,XRD,FTIR,and XPS.Interestingly,Mn doping was found to improve the degree of order,and the ordered mesoporous structure was optimized at 3%doping.Meanwhile,MnO_xwas highly dispersed in the ordered mesoporous materials to yield good catalytic ozonation performance.Phenol could completely be degraded in 20 min and mineralized at 79%in 60 min.Thus,the catalyst greatly improved the efficiency of degradation and mineralization of phenol when compared to single O_3or O_3+TiO_2.Finally,the reaction mechanism of the catalyst was discussed and found to conform to pseudo-first-order reaction dynamics.

Nanocomposite sodalite/ceramic membrane for pre-combustion CO2 capture： synthesis and morphological characterization

Carbon capture and storage （CCS） is amongst the possible options to reduce CO2 emission. In the application of CCS, CO2 capture techniques such as adsorption and membrane system have been proposed due to less energy requirement and environmental benign than the absorption process. However, membrane system has drawbacks such as poor membrane reproducibility, scale-up difficulty and high cost of the membrane supports. In this study synthesis and characterization of nanocomposite sodalite （HS）/ceramic membrane via ＂pore-plugging＂ hydrothermal synthesis （PPH） protocol for pre- combustion CO2 capture is reported. The morphology and crystallinity of the as-prepared membranes were checked with scanning electron microscopy and X-ray diffraction. Surface chemistry of the membrane was examined with Fourier Transform Infrared spectroscopy. In nanocomposite architecture membranes, zeolite crystals are embedded within the pores of the supports instead of forming thin-film layers of the zeolite crystals on the surface of the supports. Compared to the conventional in situ direct hydrothermal synthesis, membranes obtained from PPH possess higher mechanical strength and thermal stability. In addition, defect control with nanocomposite architecture membranes is possible because the zeolite crystals are embedded within the pores of the support, thereby limiting the maximum defect size to the pore size of the support. Furthermore, the nanocomposite architecture nature of the membranes safeguards the membrane from shocks or abrasion that could promote formation of defects. The aforementioned advantages of the nanocomposite architecture membranes could be beneficial in developing high performance and cost-effective membrane materials for pre-combustion CO2 capture.

Concentration and Chemical Speciation of Heavy Metals in Sludge and Removal of Metals by Bio-surfactants Application

The concentration and chemical speciation of heavy metals including REEs （rare earth elements）, Th （thorium） and U （uranium） in domestic sludge and electroplating sludge were investigated, and those of the domestic sludge were compared with those of natural soil. Removal of heavy metals in electroplating sludge was studied with bio-surfactants （saponin and sophorolipid） by batch and column experiments. The results suggested that heavy metals have greater concentrations and exist as more relatively unstable fraction in sludge than those in Natural soil. Nonionic saponin is more efficient than sophorolipid for the removal of heavy metals from the electroplating sludge, and mainly reacts with carbonate state （i.e., F3） and Fe-Mn oxide state （i.e., F5） fractions. The recovery efficiency of heavy metals in leachates from the electroplate sludge was attained 88%-97%. Saponin can be reused and be a promising and cost-effective material for the removal of heavy metals in sludge.

钙钛矿La_(1-x)Zn_xMnO_3薄膜结构及巨磁电阻

采用射频磁控溅射法分别在LaAlO3(LAO)(001)和SrTiO3(STO)(001)单晶基片上沉积了La1-xZnxMnO3(x=0.3,0.5,0.7)系列薄膜。通过X射线衍射,原子力显微镜,X射线光电子能谱和四探针法等分别研究了在基片LAO和基片STO上沉积的La1-xZnxMnO3薄膜的相结构、微形貌、表面化学态和磁电阻等性质。结果表明:薄膜在空气中900℃退火2h后,晶粒与基片之间形成了稳定的外延结构。La0.5Zn0.5MnO3和La0.7Zn0.3MnO3薄膜的晶粒生长良好。在温度为300K,磁场为1.5T的条件下,在LAO上沉积的La0.5Zn0.5MnO3薄膜和在STO上沉积的La0.7Zn0.3MnO3薄膜的巨磁电阻变化分别高达25%和28%。

Presentation matters： Identity of gold nanocluster capping agent governs intracellular uptake and cell metabolism

Au nanoclusters （AuNCs） hold tremendous potential to be employed in a wide variety of biological applications. Despite the rapid development in the field of NCs synthesis, a comprehensive understanding of how cells interact with this class of ultra-small nanoparticles （〈2 nm） having defined sizes and surface chemistry, remains poorly understood. In this study, we show that the choice of the surface ligand used to protect AuNCs can significantly perturb cellular uptake and intracellular redox signaling. A panel of monodisperse, atomically precise AuNCs with different core Au atom number （i.e., Auls, Au18 and Au25） protected with either mercaptopropionic acid （MPA） or glutathione （GSH） capping agent were synthesized and their effects on the generation of intracellular reactive oxygen species （ROS）, cytotoxicity and genotoxicity of the NCs were assessed. Both mitochondrial superoxide anion （O2^-） and cytoplasmic ROS were found to be higher in cells exposed to MPA but not GSH capped AuNCs. The unregulated state of intracellular ROS is correlated to the amount of internalized AuNCs. Interestingly, MPA-AuNCs induction of ROS level did not lead to any detrimental cellular effects such as cell death or DNA damage. Instead, it was observed that the increase in redox status corresponded to higher cellular metabolism and proliferative capacity. Our study illustrates that surface chemistry of AuNCs plays a pivotal role in affecting the biological outcomes and the new insights gained will be useful to form the basis of defining specific design rules to enable rational engineering of ultra-small complex nanostructures for biological applications.

Honeycomb silicon: a review of silicene

Silicene, a new allotrope of silicon in a twodimensional honeycomb structure, has attracted intensive research interest due to its novel physical and chemical properties. Unlike carbon atoms in graphene, silicon atoms prefer to adopt sp2/sp3-hybridized state in silicene,enhancing chemical activity on the surface and allowing tunable electronic states by chemical functionalization. The silicene monolayers epitaxially grown on Ag(111) surfaces demonstrate various reconstructions with different electronic structures. In this article, the structure, phonon modes, electronic properties, and chemical properties of silicene are reviewed based on theoretical and experimental works in recent years.

Gas adsorbate-induced Au atomic segregation and clustering from Cu(Au)

Surface compositional and phase segregation in an alloy can change its functionality, especially for applications where surface structure and chemistry play a vital role.For instance, the surface status of alloy catalysts significantly affects their catalytic performance for both heterogeneous and electrochemical processes. Surface segregation is believed to be driven by the difference in surface energy to reduce the total free energy of the alloy. However, the atomistic processes during the segregation process remain elusive, especially for gas molecule-induced segregation, where both structural and chemical reordering may occur. Herein, we achieved in-situ atomic-scale visualization of the surface segregation behaviors of a solid solution Cu(Au) alloy under the CO gas by an aberration-corrected environmental transmission electron microscope. CO-induced Cu(Au) surface ordering structures largely change the surface chemistry of the alloy. Further gas exposure at elevated temperature could facilitate Au atom diffusion through a specific "atomic channel" structure for dealloying and clustering on the surface. The segregated Au nanoparticles show rich phase and morphological dynamics interacting with the alloy surface, where the gas adsorption also plays an important role. These atomic insights provide direct evidence for the surface segregation and dealloying mechanisms of bimetallic alloys, and highlight the role of gas adsorbate in these surface processes.