含铁矿物的表面催化氧化作用及其环境意义

了解含铁矿物在环境地球化学和生物地球化学中所起的作用,重点在于介了解含铁矿物表面催化氧化作用对重金属As( ),Cr( ),U( )离子的表面还原反应,以及对有机污染物卤代烷烃、苯、氯苯、硝基苯类等芳香化合物的降解及退氯化作用,进而了解表面催化氧化作用的机制。

Pt-WO_3/C电极表面活化处理对乙醇和CO的电催化氧化作用

运用一种新的电极表面活化处理的方法,使乙醇和CO在Pt-WO3/C电极上的电催化氧化活性大幅度提高.发现无论在中性溶液中还是在酸性溶液中,乙醇在表面活化处理后的Pt-WO3/C电极上起始氧化电位负移,氧化峰电流密度在酸性介质中增加到未表面活化处理前的2.1倍;中性介质中增加到表面处理前的1.9倍,其主要原因是表面活化处理后,一方面增加了催化剂Pt的活性表面,另一方面也促进了吸附的CO的电氧化,减少了CO对电极表面的毒化作用.

铁氰化镍修饰电极对多巴胺电催化氧化作用的研究(英文)

本文将玻碳（GC）电极置入1mol·L－1NaNO3＋1mmol·L－1NiNO3＋1mmol·L－1K3Fe（CN）6混合溶液中进行循环伏安扫描（CV）可现场制备出性能稳定、厚度可控的NiHCF／GC修饰电极，且其电化学可逆性较NiHCF／Ni更好．研究表明对于在空白玻碳电极上氧化电位较高的神经传导物质多巴胶（DA），NiHCF膜可通过媒介作用使其氧化电位降低约200mV，大大提高其电子转移速率，利用这种电催化作用，可较好地对溶液中DA含量进行测定．

铁(氢)氧化物矿物对有机污染物的光催化氧化作用

对水溶液中(氢)氧化铁的光催化氧化反应的发展与机理研究进行了总结,着重对近十年来应用针铁矿/过氧化氢进行光催化氧化环境中有机物的研究进展及其环境矿物学意义作了概述和探讨。采用天然生物矿化的纳米针铁矿/过氧化氢以偶氮染料甲基橙为光解模型物进行了光催化氧化的初步研究,结果表明铁细菌形成的针铁矿具有降解生物难降解的有机污染物的能力。在甲基橙溶液初始浓度为30mg/L,铁细菌矿化的针铁矿用量2 5g/L,反应体系H2O2的初始浓度97mmol/L,pH值为6 92,15W紫外灯照射2h后,甲基橙浓度可降低33%。

溴酸钾氧化酚藏花红催化光度法测定痕量亚硝酸根

在硫酸介质中 ,根据亚硝酸根对溴酸钾氧化酚藏花红的褪色反应具有较强的催化作用 ,建立了一种催化光度法测定痕量亚硝酸根的新方法 .本法的线性范围为 0 .36～ 0 .5 6 μg/mL、检出限为 2 .44× 10 -8g/mL ,具有良好的选择性 .用于测定雨水中痕量亚硝酸根 ,其相对标准偏差为 2 .8%～ 3.5 %,水样加标回收率为 98%～10 2 %,结果满意 .

多壁碳纳米管修饰电极对对苯二酚的催化作用

将多壁碳纳米管修饰到玻碳电极的表面,制备出对对苯二酚具有电催化氧化作用的碳纳米管修饰电极.考察了该电极在不同电解质溶液及不同扫速下其循环伏安图的峰电位及峰电流,发现该电极在H2SO4中对对苯二酚具有良好的催化氧化作用.

新型高效催化剂用于“人工光合作用”制氧

美国能源部Brookhaven国家实验室和日本分子科学研究所的科学家正在模拟以制备非污染性燃料（如用于燃料电池的氢燃料）为目的的复杂光合作用的自然过程。科学家在《无机化学》杂志上报道的一篇“制氧”论坛中谈到，他们能够模拟自然界光合作用过程中的水氧化催化作用。水氧化，是光合作用的一部分，也是“水裂解”（水裂解为氢气和氧气）过程中非常复杂的反应。水裂解制氢需要大量的太阳能和金属催化剂将稳定的水分子激活。该反应伴随着两个独立的半反应：水分子氧化生成氧气，伴随质子和电子产生；质子和电子结合生成氢分子。

聚铝试剂膜修饰电极的电催化性能研究

铝试剂能在玻碳电极表面电聚合成膜，研究该膜的电催化性能，发现它对水溶液中的抗坏血酸、亚硝酸根均有良好的电催化氢化作用，催化峰电流与其浓度均成良好的线性关系，且该修饰电极具有良好的稳定性，有分析应用的意义．

Promoting effects of Fe_2O_3 to Pt electrocatalysts toward methanol oxidation reaction in alkaline electrolyte

Fe_2O_3 nanorods and hexagonal nanoplates were synthesized and used as the promoters for Pt electrocatalysts toward the methanol oxidation reaction（MOR） in an alkaline electrolyte.The catalysts were characterized by scanning electron microscopy,transmission electron microscopy,X-ray diffraction,X-ray photoelectron spectroscopy,cyclic voltammetry and chronoamperometry.The results show that the presence of Fe_2O_3 in the electrocatalysts can promote the kinetic processes of MOR on Pt,and this promoting effect is related to the morphology of the Fe_2O_3 promoter.The catalyst with Fe_2O_3 nanorods as the promoter（Pt-Fe_2O_3/C-R） exhibits much higher catalytic activity and stability than that with Fe_2O_3 nanoplates as the promoter（Pt-Fe_2O_3/C-P）.The mass activity and specific activity of Pt in a Pt-Fe_2O_3/C-R catalyst are 5.32 A/mgpt and 162.7 A/m^2_（Pt）,respectively,which are approximately 1.67 and 2.04 times those of the Pt-Fe_2O_3/C-P catalyst,and 4.19 and 6.16 times those of a commercial PtRu/C catalyst,respectively.Synergistic effects between Fe_2O_3 and Pt and the high content of Pt oxides in the catalysts are responsible for the improvement.These findings contribute not only to our understanding of the MOR mechanism but also to the development of advanced electrocatalysts with high catalytic properties for direct methanol fuel cells.

分子筛合成新进展

第12届国际沸石会议于1998年7月5～10日在美国马里兰州巴尔的摩市举行。与会代表756人,其中中国代表约50余人。会议有5个大会邀请报告:①沸石中分子的传输(德国J.Karger教授);②分子筛的氧化还原催化作用(捷克B.Wichterlopa教授);③沸石应用综述(美国J.M.Garces教授);④用计算机发现新骨架结构的沸石(美国M.M.J.Treacy);

Enhanced photochemical oxidation ability of carbon nitride by π-πstacking interactions with graphene

A one-pot method for the preparation of g-C3N4/reduced graphene oxide（rGO） composite photocatalysts with controllable band structures is presented.The photocatalysts are characterized by Fouirer transform infrared spectroscopy,X-ray diffraction,scanning electron microscope,transmission electron microscope,and Mott-Schottky analysis.The valance band（VB） of g-C3N4 exhibits a noticeable positive shift upon hybridizing with rGO,and thus results in a strong photo-oxidation ability.The g-C3N4/rGO composites show a higher photodegradation activity for 2,4-dichlorophenol（2,4-DCP） and rhodamine B（RhB） under visible light irradiation（λ≥420 ran）.The g-C3N4/rGO-1sample exhibits the highest photocatalytic activity,which is 1.49 and 1.52 times higher than that of bulk g-C3N4 for 2,4-DCP and 1.52 times degradation,respectively.The enhanced photocatalytic activity for g-C3N4 originates from the improved visible light usage,enhanced electronic conductivity and photo-oxidation ability by the formed strong π-π stacking interactions with rGO.

Structure-activity relationship in Pd/CeO2 methane oxidation catalysts

Palladium based catalysts are the most active for methane oxidation. The tuning of their composition, structure and morphology at macro and nanoscale can alter significantly their catalytic behavior and robustness with a strong impact on their overall performances. Among the several combinations of supports and promoters that have been utilized, Pd/CeO2 has attracted a great attention due to its activity and durability coupled with the unusually high degree of interaction between Pd/Pd O and the support. This allows the creation of specific structural arrangements which profoundly impact on methane activation characteristics. Here we want to review the latest findings in this area, and particularly to envisage how the control(when possible) of Pd-CeO2 interaction at nanoscale can help in designing more robust methane oxidation catalysts.

Synergetic photo-epoxidation of propylene with molecular oxygen over bimetallic Au–Ag/TS-1 photocatalysts

Au-Ag bimetallic nanoparticle‐supported microporous titanium silicalite‐1catalysts were prepared via a hydrothermal‐immersion method,and their structures were examined.These materials serve as efficient catalysts for the photosynthesis of propylene oxide via the epoxidation of propene.The Au/Ag mass ratio and reaction temperature were demonstrated to have significant effects on the catalytic activity and selectivity of propylene oxide.The optimal formation rate(68.3μmol/g·h)and selectivity(52.3%)toward propylene oxide were achieved with an Au:Ag mass ratio of4:1.Notably,the strong synergistic effect between Au and Ag resulted in superior photocatalysis of the bimetallic systems compared with those of the individual systems.A probable reaction mechanism was proposed based on the theoretical and experimental results.

Transformation of carbon dioxide into valuable chemicals over bifunctional metallosalen catalysts bearing quaternary phosphonium salts

The chemical transformation of CO2under mild conditions remains a great challenge because of itsexceptional kinetic and thermodynamic stability.Two important reactions in the transformation ofCO2are the N‐formylation reaction of amines using hydrosilanes and CO2,and the cycloaddition ofCO2to epoxides.Here,we report the high efficiency of bifunctional metallosalen complexes bearingquaternary phosphonium salts in catalyzing both of these reactions under solvent‐free,mild conditionswithout the need for co‐catalysts.The catalysts’bifunctionality is attributed to an intramolecularcooperative process between the metal center and the halogen anion.Depending on the reaction,this activates CO2by permitting either the synergistic activation of Si–H bond via metal–hydrogen coordinative bond(M–H)or the dual activation of epoxide via metal–oxygen coordinativebond(M–O).The one‐component catalysts are also shown to be easily recovered and reusedfive times without significant loss of activity or selectivity.The current results are combined withprevious work in the area to propose the relevant reaction mechanisms.

Pt supported on octahedral Fe_3O_4 microcrystals as a catalyst for removal of formaldehyde under ambient conditions

Several catalysts comprising Pt supported on octahedral Fe3O4（Pt/Fe3O4） were prepared by a facile method involving co-precipitation followed by thermal treatment at different temperatures. A variety of characterization results revealed that this preparation process afforded highly crystalline octahedral Fe3O4 with a uniform distribution of Pt nanoparticles on its surface. The thermal-treatment temperature significantly influenced the redox properties of the Pt/Fe3O4 catalysts. All the Pt/Fe3O4 catalysts were found to be catalytically active and stable for the oxidation of low-concentration formaldehyde（HCHO） with oxygen. The catalyst prepared by thermal treatment at 80 °C（labelled Pt/Fe3O4-80） exhibited the highest catalytic activity, efficiently converting HCHO to CO2 and H2 O under ambient temperature and moisture conditions. The excellent performance of Pt/Fe3O4-80 was mainly attributed to beneficial interactions between the Pt and Fe species that result in the formation a higher density of active interface sites（e.g., Pt-O-FeO x and Pt-OH-FeO x）. The introduction of water vapor improves the catalytic activity of the Pt/Fe3O4 catalysts as it participates in a water-assisted dissociation process.

Simultaneous formation of a C/N-TiO_2 hollow photocatalyst with efficient photocatalytic performance and recyclability

Herein,we report a unique approach towards the preparation of C-modified and N-doped TiO2 hollow spheres(C/N-TiO2).TEM,SEM,and XPS analyses were used to confirm that the carbon and nitrogen co-decorated TiO2 photocatalyst was formed.Carbon-decoration improves the visible-light absorption and speeds up the separation of the photo-generated electron-hole pairs.C/N-TiO2 not only narrows the band gap of TiO2,but also exhibits excellent photocatalytic activity for the degradation of tetracycline and tetracycline hydrochloride.In addition,the C/N-TiO2 photocatalyst shows excellent recyclability for water decontamination,making it a promising candidate to purify aquatic contaminants.

LSDA+U study on the electronic and anti-ferromagnetic properties of Ni-doped CuO and Cu-doped NiO

Doping is an effective way to improve the activity of photocatalysts.The effect of doping on the magnetic properties of some photocatalysts that are easily recycled was studied using the local spin density approximation(LSDA)+U method on typical divalent metal oxide semiconductors CuO,NiO,Ni‐doped CuO,and Cu‐doped NiO.It is found that the influence of Ni doping on the spatial structure of CuO and that of Cu doping on the spatial structure of NiO are negligible because of the similar radii of Ni2+and Cu2+.The valence band and conduction band for Ni‐doped CuO are clearly spin‐split,corresponding to a net effective magnetic moment ofμeff=1.66μB.This may improve the photocatalytic efficiency and raise the recycle rate of photocatalysts.In the Cu‐doped NiO system,the presence of Cu3d states near to the Fermi level increases the width of the valence band and narrows the band gap with respect to that in pure NiO.Beyond the Cu3d states,within the band gap,appear two energy levels around the Fermi level,which may effectively separate the electron‐hole pair and also lead to enhanced absorption of visible light and infrared light.It can be concluded that the observed changes in the band structure may be helpful for improving the activity of photocatalysts and the doped systems have net magnetic moments,meaning that they are easily recycled and can be reused.

Preparation of p-menthane hydroperoxide from p-menthane in presence of metalloporphyrins

The aerobic oxidation of p-menthane to p-menthane hydroperoxide （PMHP） in the presence of metalloporphyrins was investigated in an intermittent mode under an atmospheric pressure of air. Several important reaction parameters, such as the structure of metalloporphyrin, the air flow rate, and the temperature, were studied. The preliminary mechanism of the aerobic oxidation of p-menthane catalyzed by metalloporphyrins was also discussed. The results show that the reaction is greatly accelerated by the addition of metalloporphyrins at very low concentration, in terms of both the yield and formation rate of PMHP, and the high selectivity of PMHP is maintained during the reaction. Temperature of 120 ℃ and reaction time of around 5 h are the optimal conditions for the best result in the presence of 0.06 mmol/L monomanganeseporphyrins （（p-Cl）TPPMnC1）. Furthermore, the yield of PMHP is increased remarkably when the reaction is carried out under programmed temperature compared with the constant temperature. When the reaction is catalyzed by 0.06 mmol/L（（p-Cl）TPPMnCl） at the air flow rate of 600 mL/min and 120 ℃ for 4 h, and then the temperature is reduced to 110 ℃, for another 4 h, the yield of PMHP reaches 24.3 %, which is higher than that of the reaction at a constant temperature of 120 ℃ or 110 ℃ for 8 h.

Revealing the unexpected promotion effect of EuO_x on Pt/CeO_2 catalysts for catalytic combustion of toluene

Pt/Eu2O3-CeO2 materials with different Eu concentrations were prepared and applied to toluene destruction,and the remarkable promotion impact of EuOx on Pt/CeO2 can be observed.The characterization results reveal that the presence of EuOx significantly enhances the redox property,lattice O concentration,and Ce3+ ratio of the Pt/CeO2 material,which facilitates the dispersion and activity of Pt active sites and thus accelerates the decomposition process of toluene.Among all catalysts,a sample with an Eu content of 2.5 at.%(Pt/EC-2.5)possesses the best catalytic activity with 0.09 vol% of toluene completely destructed at 200 ℃ under a relatively high GHSV of 50000 h^-1.The possible reaction pathway and mechanism of toluene combustion over Pt/Eu2O3-CeO2 samples are presented according to in-situ DRIFTS,which confirms that the toluene oxidation process obeys the Mars-van Krevelen mechanism with aldehydes and ketones as primary organic intermediates.