碳量子点增强气液相化学发光检测二氧化碳北大核心CSCD

采用一步溶剂热法合成了能够发射绿色荧光的水溶性碳量子点(CDs),并对其进行了透射电子显微镜(TEM)、紫外可见光谱、荧光光谱以及红外谱图等一系列表征。基于该CDs增强的H_(2)O_(2)-KOH-CO_(2)气液相化学发光体系,利用自助研发的气液相化学发光检测仪实现了对CO_(2)气体的实时在线检测。研究了H_(2)O_(2)、KOH以及CDs浓度对发光强度的影响,结果表明当H_(2)O_(2)浓度为0.15 mol/L、KOH浓度为0.40 mol/L以及CDs溶液与KOH溶液体积比为1∶2时所测得的化学发光强度最大。在最优条件下,在0.196~49 mg/L范围内,CO_(2)浓度与发光强度呈现出良好的线性关系;计算得到二氧化碳的检测限为0.049 mg/L;重复检测11次1.96和4.56 mg/L的CO_(2)的相对标准偏差分别为1.46%和0.65%。采用该方法检测CO_(2)具有灵敏度高、选择性好、精密度高以及能够实现连续在线检测等优点。     

pH and H2O2 dual-responsive carbon dots for biocatalytic transformation monitoring

Carbon dots with strong orange light emission, pH and H₂O₂ dual-responsive characteristics, were prepared and applied for probing enzyme-mediated biocatalytic transformations via the fluorescence quenching.     

Fluorescence Intensity Enhancement of Green Carbon Dots: Synthesis,Characterization and Cell Imaging

The hydrothermal treatment of green carbon dots (CDs) is an appropriate fluorescent probe synthesis method. CDs are exploited as biological staining agents, especially for cellular detection and imaging. The nitrogen-doped green carbon dots (N-CDs) formation can improve the fluorescence intensity property in a one-step process. Here, we report two N-CDs from lemon and tomato extraction in the presence of hydroxylamine. Lemon and tomato N-CDs showed the blue fluorescence under ultraviolet radiation of about 360 nm. The characterization of CDs and N-CDs showed the presence of N-H and C–N bonds which enhanced the fluorescence efficiency. The mean size of lemon and tomato N-CDs were about 2 and 3 nm with an increased quantum yield (QY) of 5% and 3.38%, respectively. The CDs and N-CDs cytotoxicity assay exhibited high cell viability approximately 85% and 73%, respectively. N-CDs show superior fluorescent intensity in different solvents and significant stability under long-time UV irradiation, different PH and high ionic strength. Our results indicated that the use of N-CDs in cell imaging can lead to fluorescence intensity enhancement as well as proper biocompatibility. Therefore, the safe and high fluorescence intensity of green N-CDs can be utilized for fluorescent probes in biolabeling and bioimaging applications.     

熔盐辅助微波法制备g-C3N4包覆MgO-Al2O3-Fe2O3异质结催化剂及其光催化制过氧化氢性能

H₂O₂ is industrially produced by the anthraquinone method, in which energy consumption is high because it involves multistep hydrogenation and oxidation reactions. Photocatalytic production of H₂O₂ has received increasing attention as a sustainable and eco-friendly alternative to conventional anthraquinone-based and electrochemical production processes. Herein, we report a novel molten salt-assisted microwave process for the synthesis of a g-C₃N₄-coated MgO-Al₂O₃-Fe₂O₃ (MAFO) heterojunction photocatalyst with outstanding H₂O₂ production ability. The addition of a molten salt during synthesis changes the morphology of the as-prepared catalysts and influences the degree of polycondensation of melamine, leading to a change in the band gap energy. The cladding structure forms the maximum area of the heterojunction, leading to strong electronic coupling between the two components. This strong electronic coupling results in a more effective separation of the photogenerated electron-hole pairs and a faster interfacial charge transfer, leading to higher H₂O₂ formation rate. The equilibrium concentration and formation rate of H₂O₂ over the as-prepared heterojunction catalyst were 6.3 mmol·L^-1 and 1.42 mmol·L^-1·h^-1, which are much higher than that reported for g-C₃N₄ and MAFO individually. In addition, the H₂O₂ decomposition rate also decreases over the as-prepared heterojunction catalysts. A possible mechanism and the electron transfer routes have been proposed based on a free radical trapping experiment.     

铌酸锂多晶粉体的水热合成及表征

铌酸锂(LiNbO₃)晶体由于本身具有的优良性能在许多领域中都获得了广泛的应用.以LiOH·H₂O和Nb₂O₅为原料采用水热合成法成功地合成了铌酸锂多晶粉体,并采用FTIR谱、XRD谱和SEM对产物进行了表征.结果表明,采用水热合成法能够得到结晶完整的四方柱形LiNbO₃多晶粉体.同时考察了反应温度、晶化时间和Li源对水热合成产物的影响.     

Organelle targetable fluorescent probes for hydrogen peroxide

The review summarized organelle target strategies, structures, fluorescence behavior and biological applications of H₂O₂ fluorescent probes with mitochondria, nuclei and lysosomes-targetable ability.     

MOF derived Co3O4/N-doped carbon nanotubes hybrids as efficient catalysts for sensitive detection of H2O2 and glucose

Developing enzyme-free sensors with high sensitivity and selectivity for H2O2 and glucose is highly desirable for biological science.Especially,it is attractive to exploit noble-metal-free nanomaterials with large surface area and good conductivity as highly active and selective catalysts for molecular detection in enzyme-free sensors.Herein,we successfully fabricate hollow frameworks of Co3O4/N-doped carbon nanotubes(Co3O4/NCNTs)hybrids by the pyrolysis of metal-organic frameworks followed by calcination in the air.The as-prepared novel hollow Co3O4/NCNTs hybrids exhibit excellent electrochemical performance for H2O2 reduction in neutral solutions and glucose oxidation in alkaline solutions.As sensor electrode,the Co3O4/NCNTs show excellent non-enzymatic sensing ability towards H2O2 response with a sensitivity of 87.40μA(mmol/L)^-1 cm^-2,a linear range of 5.00μmol/L-11.00 mmol/L,and a detection limitation of 1μmol/L in H2O2 detection,and a good glucose detection performance with 5μmol/L.These excellent electrochemical performances endow the hollow Co3O4/NCNTs as promising alternative to enzymes in the biological applications.     

Aerosol-assisted submicronγ-Fe2O3/C spheres as a promising heterogeneous Fenton-like catalyst for soil and groundwater remediation:Transport,adsorption and catalytic ability

This research reports a novel heterogeneous Fenton-like catalyst which could freely move through the model sediments and easily seize the pollutants in addition to efficiently catalyze H2O2,well suitable for soil and groundwater remediation.Herein,submicron y-Fe2O3/C spheres were synthesized through a facile one-step aerosol-based process.In a series of column tests,these spheres exhibit better transport ability due to their optimal size,conforming to the prediction by the Tufenkji-Elimelech filtration theo ry.Meanwhile,y-Fe2O3/C spheres could act as a strong adsorbent for organic pollutants owing to the presence of carbon,thereby providing a driving force to gather contaminants into their vicinity and facilitating the reaction.In addition,immobilization of y-Fe2O3 nanoparticles into carbon spheres protects iron oxides from aggregation,and thus retains the number of active sites for catalytic decomposition of H2O2.Hence,the system containing the as-prepared y-Fe2O3/C spheres and H2O2 shows the high removal efficiency and degradation efficiency in the remediation of recalcitrant organic contaminants such as methylene blue and sulfamethoxazole.     

自然水体生物膜体系中过氧化氢浓度的影响因素

以过氧化氢(H₂O₂)为自然水体生物膜产生的活性氧(ROS)的代表, 通过模拟实验, 研究了水-自然水体生物膜体系中光/暗变化、 生物膜的避光预处理与数量、 有机配体和pH值对体系中H₂O₂浓度的影响. 结果表明, 光照可快速增加体系中H₂O₂浓度, 光照转为无光时体系H₂O₂浓度下降(约为光照时的2/3); 避光预处理会显著降低体系中H₂O₂的产生速率和浓度; 生物膜数量的增减会导致体系H₂O₂浓度的相应增减; 有机配体的存在会使体系内H₂O₂浓度下降(约1/2~1/3); pH=7和5的体系中H₂O₂的浓度高于pH=9的体系(高出约1.5倍). 上述各因素主要通过影响生物膜生产H₂O₂、 H₂O₂自然分解和生物膜去除H₂O₂ 3种作用来影响体系H₂O₂浓度.     

光催化氧气还原制备H2O2

H₂O₂广泛应用于化工和环保领域,其分解的唯一产物是水,有利于生产与自然生态系统的协调可持续发展。工业上H₂O₂的合成主要是通过蒽醌法间接合成,该方法能耗大,污染环境。而直接由H₂与O₂混合制备H₂O₂,具有极大的安全风险,且需要消耗大量H₂。通过光催化技术将O₂和H₂O转化成H₂O₂的方法,避免了H₂与O₂的直接混合,同时采用取之不尽的太阳能作为能量来源,近年来备受关注。本文总结了光催化还原O₂制备H₂O₂的研究进展,对比分析了不同催化体系,如g-C₃N₄、TiO₂以及其他光催化剂的反应性能及调控措施,介绍了光催化制备H₂O₂的机理,并对该领域的发展进行了展望。     

醋酸酮催化二硫醚与四氢呋喃的氧化偶联反应

研究了醋酸酮催化二硫醚与四氢呋喃以氧化偶联反应构建C—S键。 结果表明,在醋酸酮(10%摩尔分数)、二硫醚(0.5 mmol)、四氢呋喃(2 mL)和双氧水(35%,2倍化学计量),反应温度120 ℃条件下,二硫醚与四氢呋喃能够顺利地发生氧化偶联反应,生成相应的C—S键化合物,合成硫醚类化合物产率中等到良好。 该反应以双氧水为氧化剂,具有环境友好等特性。     

溶解有机质对光照自然水体生物膜体系中H2O2生成的影响

通过模拟实验研究了生物膜胞外聚合物(EPS)和乙二胺四乙酸(EDTA) 2种典型溶解有机质(DOM)成分对自然水体生物膜体系中过氧化氢(H₂O₂)生成特征的影响, 并研究了体系初始pH值、 DOM浓度、 溶解氧(DO)等因素的影响. 结果表明, DOM的存在对自然水体生物膜体系中H₂O₂的生成有明显影响. 光照能促使EPS产生H₂O₂, 而EPS的存在对生物膜产生H₂O₂的直接影响不显著, EPS与生物膜共存体系中的H₂O₂由二者共同产生; EDTA本身不产生H₂O₂, 且对H₂O₂分解影响很小, 但会显著抑制生物膜产生H₂O₂, 且浓度越高抑制作用越明显. 体系pH值、 DOM浓度和DO均能不同程度影响EPS产生H₂O₂及EDTA抑制生物膜产生H₂O₂的作用.     

Ce0.5Zr0.5O2修饰的Ni/SiC、Fe/SiC和Co/SiC催化燃烧甲烷性能

以铈锆固溶体(Ce0.5Zr0.5O2)修饰的高比表面积SiC为载体,采用两步浸渍法制备了Ni、Fe和Co基催化剂,研究了其在煤层气催化燃烧脱氧中的催化活性和稳定性.利用X射线衍射(XRD)、X射线光电子能谱(XPS)、电感耦合等离子体质谱(ICP-MS)、高分辨透射电子显微镜(HRTEM)、比表面积(BET)、热重分析(TGA)和H2程序升温还原(H2-TPR)对催化剂进行了表征.分析结果表明,Ni、Fe和Co部分进入Ce0.5Zr0.5O2固溶体晶格内部,导致催化剂体相形成更多的缺陷;同时Ce0.5Zr0.5O2固溶体有助于加速金属氧化物和金属之间氧化还原过程的进行,促进了氧吸附、传输和对甲烷的活化.另外,SiC和Ce0.5Zr0.5O2固熔体良好的抗积碳性能,有效避免了催化剂在富甲烷反应气氛中因积碳而失活,从而使三种催化剂均具有优良的催化燃烧脱氧活性和稳定性.其中,Co/Ce0.5Zr0.5O2/SiC活性最高,可在320℃活化催化甲烷,并在410℃实现完全脱氧.     

Ultraviolet stimulation of hydrogen peroxide production using aminoindazole, diaminopyridine, and phenylenediamine solid polymer complexes of Zn(II)

Hydrogen peroxide (H₂O₂) is a valuable chemical commodity whose production relies on expensive and energy intensive methods. If an efficient, sustainable, and inexpensive solar-mediated production method could be developed from the reaction between dioxygen and water then the use of H₂O₂ as a fuel may be possible and gain acceptance. When concentrated at greater than 10 M, H₂O₂ possesses a high specific energy, is environmentally clean, and is easily stored. However, the current method of manufacturing H₂O₂ via the anthraquinone process is environmentally unfriendly making the unexplored nature of its photochemical production at high concentration from solar irradiation of interest. Towards this end, we studied the concentration and quantum yield of hydrogen peroxide produced in an ultraviolet (UV-B) irradiated environment using solid, Zn(II)-centered, complexes of amino-substituted isomers of indazole, pyridine, and phenylenediamine to catalyze the reaction. Aqueous suspensions in contact with air were exposed to 280–360-nm light from a low-power lamp. Of the ten complexes studied, Zn-5-aminoindazole had the greatest first-day production of 63 mM/day with a 37% quantum yield and p-phenylenediamine (PPAM) showed the greatest long-term stability. Isomeric forms of the catalysts’ organic components (e.g., amino groups) affected H₂O₂ production. For example, irradiation of diaminopyridine isomers indicated 2,3-diamino and 3,4-diamino structures were the most productive, each generating 32 mM/day H₂O₂, whereas the 2,5-diamino isomer generated no H₂O₂. A significant decrease in H₂O₂ production with time was observed for all but PPAM, suggesting the possibility of a catalyst-poisoning mechanism. We propose a reaction mechanism for H₂O₂ production based on the stability of the resonance structures of the different isomers.     

负载Cr_2O_3的H_2Ti_2O_5·H_2O纳米管的制备及其作为锂离子电池正极材料的电化学性能

限制纳米电极材料倍率性能的一个重要因素是,在大电流下充放电时,纳米结构可能坍塌,造成容量迅速衰减.通过异价离子的掺杂或第二相的负载有可能弥补纳米材料的这一缺陷.本文以含有Cr2O3的锐钛矿TiO2为原料,通过超声化学-水热法,制备了负载Cr2O3的H2Ti2O5·H2O纳米管.采用X射线衍射(XRD)和透射电镜(TEM)对制得的H2Ti2O5·H2O/Cr2O3纳米管的晶体结构和微观形貌进行了表征和分析.恒流充放电测试显示,H2Ti2O5·H2O/Cr2O3(5%(w,质量分数))纳米管作为锂离子电池阳极材料具有优异的循环稳定性及倍率性能.在150mA·g-1的电流密度下,H2Ti2O5·H2O/Cr2O3纳米管的首次放电容量达到288mAh·g-1;120次循环后,充放电容量仍保持在145mAh·g-1.在1500mA·g-1的电流密度下,首次放电容量为178mAh·g-1;600次循环后,充放电容量保持在80mAh·g-1以上;继续在150mA·g-1电流密度下充放电30个循环,充放电容量达到155mAh·g-1,显示出充放电容量的可回复性.循环伏安测试结果表明,H2Ti2O5·H2O/Cr2O3纳米管的充放电过程由法拉第赝电容反应控制.该一维纳米结构在锂离子电池和非对称电容器领域显示出良好的应用前景.     

新型Brnsted-Lewis酸性催化剂LaPW_(12)O_(40)/SiO_2制备及其在催化酯化反应合成生物柴油中的应用

以十二磷钨杂多酸(Tungstophosphoric acid,H_3PW_(12)O_(40))为基体,分别通过普通浸渍法、溶胶凝胶法和超声浸渍法进行了La3+改性作用,合成了三种固体酸催化剂A-LaPW_(12)O_(40)、B-LaPW_(12)O_(40)/Si O2和C-LaPW_(12)O_(40)。采用X射线荧光光谱(XRF)、孔径比表面积测定、X射线粉末衍射(XRD)、透射电镜(TEM)、红外光谱(FT-IR)、热重(TG)、N2吸附-脱附、NH3程序升温脱附(NH3-TPD)、吡啶吸附红外光谱(Py-FTIR)、X射线光电子能谱(XPS)等方法对合成的催化剂进行了表征,并比较了以上催化剂在用于催化以油酸和甲醇为反应物经酯化反应合成生物柴油时的活性和稳定性。结果表明,B-LaPW_(12)O_(40)/Si O2具有最高催化活性,当甲醇与油酸的物质的量比为8∶1,催化剂用量为反应物总质量的2%,反应温度为65℃,反应1 h后,油酸的转化率即高达93%。循环使用B-LaPW_(12)O_(40)/Si O2催化剂六次后,油酸的转化率仍高达86.4%。B-LaPW_(12)O_(40)/Si O2的高催化活性和稳定性可归因于在溶胶凝胶的转化过程中,作为硅源材料的四乙氧基硅(TEOS)易在酸性条件下发生水解反应形成Si O2网络,进而Si O2网络中的硅醇键与H_3PW_(12)O_(40)中的H+发生配位作用,生成具有强静电吸附力的(≡Si-OH2+)(H2PW12O-40)络合物。随着该络合物的形成,促进了La3+在Si O2表面的吸附而堵塞了H_3PW_(12)O_(40)的孔道结构,抑制了H_3PW_(12)O_(40)颗粒在焙烧过程中进一步聚集长大。Si O2将作为载体并以干凝胶状态存在于B-LaPW_(12)O_(40)/Si O2催化剂中,由于Si O2凝胶的高比表面积而使B-LaPW_(12)O_(40)/Si O2具有了较大的比表面积,从H_3PW_(12)O_(40)的1.4 m2/g增加至31.3 m2/g。并且,通过吡啶吸附红外光谱确定B-LaPW_(12)O_(40)/Si O2为Br9nsted-Lewis酸型固体酸,由于Br9nsted酸位易与酯化反应过程中生成的水发生水合反应而失活,因而Lewis酸位的形成有助于减少催化剂的失活现象发生。Lewis酸位的出现可归因于(≡Si-OH2+)(H2PW12O-40)与吸附在其表面的具有强吸电子作用的La3+发生键合作用后生成了LaPW_(12)O_(40)/Si O2。     

A green and efficient deoximation using H202 catalyzed by montmorillonite-K10 supported COC12

Oximes were oxidized to the corresponding carbonyl compounds in good to high yields by environmentally friendly and green oxidant, H202 catalyzed by montmorillonite K-10 supported cobalt（Ⅱ） chloride.     

Design of a novel mitochondria targetable turn-on fluorescence probe for hydrogen peroxide and its two-photon bioimaging applications

Considering that hydrogen peroxide (H₂O₂) plays significant roles in oxidative stress, the cellular signal transduction and essential biological process regulation, the detection and imaging of H₂O₂ in living systems undertakes critical responsibility. Herein, we have developed a novel two-photon fluorescence turn on probe, named as Pyp-B for mitochondria H₂O₂ detection in living systems. Selectivity studies show that probe Pyp-B exhibit highly sensitive response toward H₂O₂ than other reactive oxygen species (ROS) and reactive nitrogen species (RNS) as well as biologically relevant species. The fluorescence colocalization studies demonstrate that the probe can localize in the mitochondria solely. Furthermore, as a bio-compatibility molecule, the highly selective and sensitive of fluorescence probe Pyp-B have been confirmed by its cell imaging application of H₂O₂ in living A549 cells and zebrafishes under the physiological conditions.     

Effective Removal of Tetracycline by Using Biochar Supported Fe3O4 as a UV-Fenton Catalyst

Novel Fe3O4-decorate hierarchical porous carbon skeleton derived from maize straw(Fe3O4@MSC)was synthesized by a facile co-precipitation process and a calcination process,which was developed as a UV assisted heterogeneous Fenton-like catalyst.The as-synthesized catalysts were characterized via X-ray powder diffraction(XRD), scanning electron microscope(SEM),transmission electron microscope(TEM),Brunauer-Emmet-Teller(BET)and vibrating sample magnetometer(VSM)at room temperature.The morphology and structure analysis revealed that the as-prepared Fe3O4@MSC retained the original pore morphology of the maize straw material.The non-uniform poly- hedral Fe3O4 grew on the whole surface of the MSC,which reduced the aggragation of Fe3O4 and provided more active sites to strengthen the UV-assisted Fenton-like reaction.As a result,the tetracycline(TC)degradation efficiency after 40 min reaction and total organic carbon(TOC)removal efficiency after 2 h reaction of Fe3O4@MSC catalyzing UV-Fenton system reached 99.2%and 72.1%,respectively,which were more substantial than those of Fe3O4@MSC/H2O2(31.5%and 2%),UV/H2O2 system(68%and 23.4%)and UV/Fe3O4/H2O2(80% and 37.5%).The electron spin resonance(ESR)results showed that the ·OH played an important role in the catalytic reaction.A possible degradation pathway of TC was proposed on the basis of the identified intermediates.Overall,the UV assisted heterogeneous Fenton-like process in Fe3O4@MSC improved the cycle of Fe^3+/Fe^2+ and activated the interfacial catalytic site,which eventually realized the enhancement of degradation and mineralization to tetracycline.     

光照下自然水体生物膜产生H2O2及其对十二烷基苯磺酸钠降解的影响

通过模拟实验研究了不同活性的自然水体生物膜在光照条件下生成过氧化氢(H₂O₂)的反应. 并研究了光照对自然水体生物膜体系中十二烷基苯磺酸钠(SDBS)降解的影响, 结合无生物膜H₂O₂溶液中SDBS的降解实验, 验证了H₂O₂对SDBS降解的作用. 结果表明, 具有生物活性的生物膜可以生成H₂O₂, 而无活性和光合作用受到抑制的生物膜则不能生成H₂O₂; 光照条件下, 生物膜体系中SDBS的降解量明显高于无光照条件下的; 光照和Fe²⁺对H₂O₂降解SDBS有促进作用.