Quantum Chemical Molecular Dynamics Studies of Bilayer Graphene Growth on a Ni(111) Surface

The mechanism of bilayer graphene nucleation and growth has been investigated by using quantum chemical molecular dynamics simulations. The results indicate that the presence of embedded nickel atoms in the upper-layer (first-layer) graphene has little impact on the evolution mechanism of the second-layer graphene precursor. The nucleation process occurs after the rapid precipitation of internal carbon atoms along with the degradation of nickel catalyst and the formation of discrete carbon polyyne chains. The second-layer graphene exhibits an attachment-limited growth on the rugged Ni(111) surface. The quality of the second-layer graphene can be reduced, and large structural holes are induced when the metal atoms are involved in the upper-layer graphene. On the contrary, high-quality upper-layer graphene can act as an excellent template for the growth of the second-layer graphene. These simulations, therefore, suggest that through carefully controlling the growth conditions, different kinds of bilayer graphene can be fabricated in a layer-by-layer mode on the Ni(111) surface

新型钴-铈催化剂的设计合成及性能研究

二氧化铈（CeO2）以其独特的储放氧性质成为催化剂领域的研究热点。对一系列的氧化还原反应，CeO2都表现出了优异的催化性能。更重要的是，大量研究表明，将CeO2与其他催化活性组分结合，设计合成新型杂化纳米催化剂，可以实现其催化性能的优化，这是由于CeO2与其他组分之间存在一定的协同作用。而且通过CeO2壳包覆纳米催化剂可以有效地改善催化剂的热稳定性。将CeO2与具有良好CO催化氧化性能的Co3O4结合可能有利于催化性能的进一步优化。本论文围绕Co3O4@CeO2核壳催化剂的设计合成开展了一系列系统性研究工作，主要包括以下几个部分： （1）我们报道了一种简单快速的自组装方法，第一次合成了高质量的Co3O4@CeO2核壳立方块。通过简单改变自组装过程中反应物的加入比例实现了对Co3O4@CeO2样品中CeO2壳层厚度的调控。对所合成的具有不同CeO2壳层厚度的Co3O4@CeO2系列样品进行了...CeO2, which possesses strong oxygen storage capacity, has become the research focus in the catalysis area. It is highly catalytic active in lots of reduction and oxidation reaction. More importantly, lots of previous literatures have shown that when combined CeO2 with other catalytic active components, the designed and fabricated novel hybrid structures show much enhanced catalytic performances. It can be attributed to the excellent synergistic effects between the two conponents. Moreover, the thermal stability of the catalysts can also be improved by encapsulating other catalytic active components in CeO2 shell. Since Co3O4 shows great performance for catalytic CO oxidation, it is reasonably considered that the catalytic performance of Co3O4 catalyst could be optimized through the combina..

原位电化学方法研究炭电极材料在电化学电容器中的储能机理

电化学电容器作为一种清洁高效的储能器件，因具有功率密度高、循环寿命长等诸多突出的优点而受到广泛关注。炭材料是电化学电容器最经典的电极材料，主要通过离子在表面的吸附或层间的插嵌来存储电量。在之前的工作中，我们发现溶剂对离子的吸/脱附、插/脱嵌过程有很大的影响。为了揭示其中的微观机理，我们开展了以下几部分工作： 1、以电化学石英晶体微天平（EQCM）为主要工具，研究了不同浓度NaClO4水溶液中活性炭电极/电解质溶液界面上离子的水合状态。结果表明，随着NaClO4浓度的增加，活性炭电极孔隙中吸附的离子的水合数不断减小。本体溶液中Na+水合数大于电极/溶液界面上的Na+水合数，即Na+在从本体溶液被吸附到活性炭孔隙的过程中发生了去溶剂化。另外，活性炭电极孔隙中Na+的水合数与活性炭负极的比电容有明显的线性关系。 2、利用EQCM研究了5 M NaClO4水溶液中的防冻添加剂（甲醇、乙醇）对Na+在活性炭表面吸附过程的影响。结果表明，甲醇、乙醇分子与Na+形成了溶剂化离子，随Na+一起吸附到了活性炭孔隙中；随着本体溶液中甲醇、乙醇浓度的增加，与吸附到活性炭孔隙中的每个Na+络合的甲醇、乙醇分子越来越多；随Na+吸附到活性炭孔隙中的甲醇、乙醇分子挤占了一定的孔隙，同时降低了双电层的介电常数，从而降低了Maxsorb电极在负电势区的比电容。 3、采用原位X射线衍射（XRD）和EQCM研究了BF4?在EC、GBL、PC中插嵌石墨电极的过程。结果表明，EC抑制了BF4?在石墨层间的插嵌。EC、GBL、PC分子都随BF4?一起嵌入了石墨电极，但嵌入的方式各不相同。同时，BF4?在石墨层间的溶剂化状态与对应的活性炭/石墨电容器的循环性能密切相关。 4、采用非原位XRD和原位Raman研究了ClO4?在EC、GBL、PC中插嵌石墨的过程。非原位XRD的测试结果表明，在PC和GBL中，ClO4?嵌入了石墨中并形成了长程有序的ClO4?-GICs，而且GBL分子极有可能也随ClO4?一起嵌入了石墨层间。而在EC中，ClO4?也嵌入了石墨中但没能形成长程有序的ClO4?-GICs，即EC抑制了ClO4?在石墨层间的插嵌。当提高测试温度时，EC对ClO4?的抑制作用会大大减弱。原位Raman结果还表明ClO4?在EC中插嵌石墨的速度要比在GBL和PC中慢很多，可逆性也差很多。 5、采用原位XRD、原位Raman和EQCM研究了PF6?在GBL中插嵌石墨的过程，并与在PC和EC中的插嵌行为进行了比较。结果表明，GBL对PF6?的插嵌也有抑制作用，尽管要比EC的抑制作用弱。同时，我们还发现PF6?在GBL中与BF4?在EC中的插嵌行为十分相似，这进一步说明GBL与EC的抑制作用在本质上是一样的。与此同时，实验结果再次表明，溶剂对活性炭/石墨电容器的性能具有决定性的影响。As a clean and highly efficient electric storage device，electrochemical capacitors have drawn widespread attention due to their numerous merits, such as high power density, long cycle life etc. Carbon materials are the most classical electrode materials for electrochemical capacitors. The charge storage of carbon materials is mainly by ions’ adsorption on the interfaces or intercalation into graphene layers. In our previous work, solvents were found to have great influence on the adsorption/desorption and intercalation/de-intercalation of ions. In order to throw light on its mechanism, following work has been done by us: (1) Electrochemical Quartz Crystal Microbalance (EQCM) was used to study the mass changes on activated carbon electrodes in various NaClO4 aqueous solutions during the course of ions adsorption into the pores of the electrode. Results indicated the hydration number of ions absorbed into the pores decreased with the concentration increase of NaClO4. The hydration number of Na+ in the bulk solutions is much larger than that in the pores of activated carbon electrodes, which demonstrated desolvation occurred during the migration of Na+ from the bulk solutions into the pores. Moreover, the specific capacitance of activated carbon negative electrodes is linearly dependent on the hydration number of Na+ in the pores of activated carbon electrodes. (2) EQCM was used to investigate the adsorption of Na+ into the micropores of activated carbons in 5 M NaClO4 aqueous solutions with different concentrations of methanol or ethanol. Molecule numbers of methanol or ethanol associated with each Na+ at the interfaces were estimated. Results showed that methanol and ethanol were adsorbed into the micropores together with Na+; the more concentrated methanol and ethanol in bulk solutions, the more molecule numbers of methanol or ethanol associated with each Na+ adsorbed into the pores; methanol and ethanol adsorbed into the pores occupied some space of the micropores and lower the dielectric constant of the double layers, which suppressed the specific capacitance of Maxsorb negative electrodes. (3) in situ XRD and EQCM techniques were adopted to probe the intercalation scenario of solvated BF4? into graphite electrodes in PC, GBL and EC. EC suppresses the insertion of BF4? into graphite. All the solvent molecules co-intercalated into graphite electrodes with BF4?，nevertheless，they are in different ways. Moreover, the solvation states of BF4? were in close relation to the cycle performance of corresponding AC/graphite capacitors. (4) ex situ XRD and in situ Raman were utilized to investigate the intercalation of ClO4? from PC-, GBL-, EC-based electrolyte solutions into graphite electrodes. ex situ XRD measurements showed ClO4? intercalated into graphite electrodes from GBL and PC, and generated ClO4?-GICs with long-range order; GBL co-intercalated with ClO4? into the space between graphene layers. In the EC-based solution, ClO4? also succeeded to insert graphite electrodes, but no ClO4?-GICs with long-range order came into being, which indicated the intercalation of ClO4? was suppressed by EC. Elevating temperature weakened the suppression effect of EC. In situ Raman demonstrated the intercalation of ClO4? from EC was slower and less reversible than that from GBL and PC. (5) in situ XRD, in situ Raman and EQCM were employed to study the intercalation of PF6? from GBL-based solution. The cases of PC- and EC-based solutions were used for comparision. Results proved the intercalation of PF6? was suppressed by GBL, even though the suppression effect of GBL was weaker than that of EC. Moreover, the intercalation behavior of PF6? in GBL was similar to that of BF4? in EC, which further demonstrated the suppression effects of GBL and EC were identical in nature. At the same time, results also proved the crucial effect of solvents on the performance of AC/graphite capacitors

氧化锆相变的荧光分析方法

为了提高燃气轮机的推重比和热效率，需要进一步提高燃气温度，涡轮叶片和其他热端部件的工作温度也相应地提高，因此热障涂层（TBCs）引起了人们的广泛关注。热障涂层是利用耐高温、抗腐蚀和低热导率的陶瓷材料，以沉积的方式与金属基底复合的表面防护涂层。目前，广泛使用的涂层顶层材料为6~8 wt.% Y2O3部分稳定化的ZrO2（8YSZ）。TBCs在长期使用过程中会发生脱落。导致涂层失效的因素很多，主要包括：陶瓷涂层与金属基底之间的热膨胀不匹配、陶瓷涂层发生相变、陶瓷涂层和粘结层之间发生反应、粘结层发生氧化和腐蚀、陶瓷涂层的烧结等。热障涂层失效机理的研究已经成为迫在眉睫的关键课题。其中，陶瓷涂层的相变是一个重要因素。目前，涂层相变的检测手段有X射线衍射（XRD）、中子衍射（ND）和Raman光谱等，这些测量方法不能完全满足涂层相变分析在探测深度、空间分辨率等方面的要求。因此，研发一种检测陶瓷涂层相变的无损检测技术有重要意义。稀土荧光离子可以在涂层任意位置实现掺杂而不影响涂层本身性质，本论文通过在8YSZ中掺杂稀土Eu3+离子，建立荧光性质和相组成之间的关系，研究新型相变检测手段。 采用高温固相合成法，通过控制Y3+的含量合成了单斜相、四方相和立方相的氧化锆粉末，研究了氧化锆相变对氧化铕荧光性质的影响。研究表明，当Eu3+处于低对称性无反演中心（单斜相）时，5D0→7F2电偶极子跃迁的强度最强，荧光寿命短；当Eu3+处于高对称性有反演中心（四方相和立方相）时，5D0→7F1磁偶极子跃迁的强度最强，荧光寿命长。可以利用Eu2O3的荧光性质来检测氧化锆的相变。不同摩尔浓度的Eu3+掺杂8YSZ的研究表明，当Eu3+的掺杂浓度为3 mol.%时，8YSZ:Eu3+具有四方相晶体结构，荧光发射强度强、荧光寿命长，是用于检测8YSZ涂层相变程度的理论最佳掺杂浓度。 采用水热合成法合成8YSZ:Eu3+ (1 mol.%)粉末，研究了该样品在高温长时间热暴露之后的相组成和荧光性质变化，并进一步探讨了两者之间的关系。在无单斜相存在时，可以利用荧光峰(I593/I608)的比值来初步评估相变的程度，荧光寿命也可以辅助说明相变的情况。采用共沉淀法合成8YSZ:Eu3+ (1 mol.%)粉末，在800℃处理6 h后，将样品置于150℃的水热釜中进行水热降解，考察其相组成和荧光性质的演化。结果表明，8YSZ:Eu3+粉末具有四方相晶体结构，在水热降解条件下，由于水的作用，发生了四方相到单斜相的相变，进一步的使粉末的荧光性质也发生改变。 采用水热合成法合成不同Eu3+掺杂浓度的ZrO2:Eu3+荧光粉，随后在不同温度下处理相同时间。研究表明，Eu3+的掺杂浓度和煅烧温度对于ZrO2:Eu3+荧光粉的晶体结构和荧光性质有重要影响。Eu3+作为三价稀土荧光离子，可以稳定四方相和立方相结构的ZrO2。四方相和立方相的ZrO2:Eu3+荧光粉是研究者关注的焦点，它们能够作为一种原材料去制备高效荧光性能的透明陶瓷。In order to meet the requirements of increasing propulsion and efficiency of gas–turbine engines, the using temperature of the turbine blade and the other parts of engine need to be further enhanced, thus thermal barrier coatings (TBCs) has attracted extensively attention. Thermal barrier coatings are protective coatings by depositing ceramic materials on a metal substrate, which have high temperature resistance, corrosion resistance and low thermal conductivity. Nowadays, the current state-of-the-art ceramic top coat material is 6~8 wt.% Y2O3 partially stabilized zirconia (8YSZ). Observations of coatings after service indicate that they can fail by cracking, delamination, and spallation, typically on cooling to room temperature. Many factors lead to the failure of thermal barrier coatings, including: the thermal expansion mismatch between ceramic top layer and metal substrate, phase transformation, chemical reaction between the ceramic top coat and bond coat, the formation and growth of a thermally grown oxide (TGO), porous coating sintering. Therefore, the research of TBCs failure mechanism is regarded as a key problem for the next generation turbine engines. Among these, the phase transformation of TBCs during service is a key factor in controlling the TBCs life. Though several techniques have been applied to assess the phase transformation of the TBCs, such as neutron diffraction, XRD and Raman spectroscopy, they still can not fully satisfy the special requirements needed in the TBCs, including the proper penetration depth and location, spatial resolution, and monitoring the evolvement. Therefore, it is necessary to develop a new non-destructive diagnostic tool to measure the phase transformation of TBCs. The rare earth elements can be doped into anywhere of the TBCs without affect the nature of the coatings, therefore, in the present work, we developed a new fluorescence measurement technique by using the materials of 8YSZ doped with Eu3+, furthermore the relationship between phase composition and fluorescence properties is established. A solid state reaction method at high temperature was used to synthesize monoclinic, tetragonal and cubic zirconia by controlling Y3+-doping concentration. The effects of phase transformation of zirconia on the fluorescence properties of Eu3+ were investigated. When the Eu3+ ions embedded in a low-symmetry site without an inversion center (monoclinic phase), the 5D0 - 7F2 electric dipole transition (EDT) around 617 nm is the strongest, and the decay lifetime is short; while in a high-symmetry site with an inversion center (tetragonal and cubic phase), the 5D0 - 7F1 magnetic dipole transition (MDT) is dominating with emission wavelength of about 593 nm, and the decay lifetime is long. So we can make use of the fluorescent properties of Eu3+ to detect the phase transformation of zirconia. In the case of different concentrations of Eu3+ doped 8YSZ, when doping concentration is 3 mol%, the nanophosphor has a pure tetragonal phase structure, the emission intensity is intense and decay lifetime is long, this concentration is the theory optimum doping concentration that can be used to indicate the extent of phase transformation. Nanocrystalline 8YSZ doped with 1 mol.% Eu3+ was synthesized via hydrothermal method. Fluorescence properties variation and phase composition variation of YSZ:Eu3+ powder were investigated after long-term, high temperature thermal exposure. The results show that when monoclinic phase is absent, the intensity ratio I593/I608 of fluorescence spectroscopy can be used to preliminary assess the extent of the phase transformation, the fluorescence lifetime can also assist in illustrating the extent of the phase transformation. Nanostructured 8YSZ doped with 1 mol.% Eu3+ was synthesized via chemical co-precipitation. The evolution of phase composition and fluorescence properties of 8YSZ:Eu3+ powder have been assessed after being subjected to hydrothermal degradat

手性磷酰胺催化的2,3’-二吲哚基取代的三芳基甲烷的不对称合成

杂-三芳基甲烷是一类结构比较特殊的骨架，在材料科学、生物化学以及药物化学等领域都有广泛的应用，其中双吲哚取代的三芳基甲烷因其在抗肿瘤方面所表现出的广阔前景而倍受关注。由于缺乏对映选择性合成双吲哚取代的三芳基甲烷的有效方法，这就制约了其手性分子在生物活性方面的研究。目前，仅有两例关于不对称合成3,3’-二吲哚基取代的三芳基甲烷的策略，而针对2,3’或2,2’-二吲哚基取代的三芳基甲烷的不对称合成尚未见报道。本论文以2-吲哚甲基醇衍生物和吲哚作为反应底物，在手性磷酰胺的催化作用下，首次实现了2,3’-二吲哚基取代的三芳基甲烷的不对称合成，并通过NMR波谱分析方法和CD光谱确定了其绝对构型。 首先，我们综述了吲哚C-3、C-2和N-1位参与的手性碳中心构建方法的研究进展，在此基础上提出了选题依据，设计了一种通过2-吲哚甲基醇和吲哚的不对称反应来合成2,3’-二吲哚基取代的三芳基甲烷的策略。接着设计并合成了一系列2-吲哚甲基醇衍生物以及BINOL为手性基本骨架的Br?nsted酸催化剂。 其次，我们通过一种在吲哚C-2位构建手性中心的新方法实现了2,3’-二吲哚基取代的三芳基甲烷的不对称合成。该方法以低反应活性的2-吲哚甲基醇衍生物作为反应底物，在最简单BINOL衍生 的N-Tf取代磷酰胺的催化作用下，经碳正离子与吲哚的不对称亲电取代反应而得以实现，且唯一副产物是水，具有简单、清洁和原子经济性的优点。同时，该反应具有较好的普适性，对于不同结构的底物，所得产物的收率几乎都大于90%，ee值35-96%。 最后，我们借助NMR波谱分析方法和CD光谱确定了手性2,3’-二吲哚基取代的三芳基甲烷类化合物的绝对构型。我们将手性2,3’-二吲哚基取代的三芳基甲烷分别与(R)-和(S)-甲氧基苯乙酸缩合，得到了一对非对映异构体结构。通过1H-NMR、1H-1H NOESY、1H-13C HSQC和1H-13C HMBC波谱分析，我们对每一个非对映异构体质子化学位移做了归属并建立了优势构象模型。最终，我们通过这对非对映异构体质子化学位移差别判定了手性2,3’-二吲哚基取代的三芳基甲烷类化合物的绝对构型。另外，CD光谱分析结果也与前面NMR判定的手性2,3’-二吲哚基取代的三芳基甲烷的绝对构型一致。这些结果为将来研究手性对2,3’-二吲哚基取代的三芳基甲烷的生物活性影响具有重要意义。Hetero-triarylmethanes are unique structural motifs and have a broad range of applications in areas such as materials science, biochemistry, and pharmaceuticals. Among which, diindolylarylmethanes represent appealing hetero-triarylmethanes due to their highly promising therapeutic utility as anticancer agents. Despite these important advances, the biological properties of the chiral derivatives remain unexplored due to the lack of effective methods for enantioselective synthesis of such compounds. So far, two protocols for the asymmetric synthesis of 3,3’-diindolylarylmethanes have been developed. However, methods for the asymmetric synthesis of 2,3’- or 2,2’-diindolylarylmethanes have not been achieved. In this dissertation, we present the first asymmetric reaction of indol-2-yl carbinol derivatives with indoles catalyzed by chiral phosphoramides for the enantioselective synthesis of 2,3’-diindolylarylmethanes and the determination of the absolute configuration of these compounds by using the combination of NMR spectroscopic and circular dichroism (CD) techniques. First, we summarised the progress of methods for the asymmetric construction of stereogenic carbon centers adjacent to the indole C-3, C-2 and N-1 positions. Based on existing works, we designed a strategy for the enantioselective synthesis of 2,3’-diindolylarylmethanes by the asymmetric reaction of indol-2-yl carbinols with indoles. Then, a series of indol-2-yl carbinol derivatives and BINOL-based chiral Br?nsted acids were designed and synthesized. Second, we have developed a novel methodology for the construction of a stereogenic carbon center adjacent to the indole C-2 position to achieve the enantioselective synthesis of 2,3’-diindolylarylmethanes successfully. The reaction of indol-2-yl carbinol derivatives was achieved in the presence of the most readily available BINOL-based N-triflylphosphoramide as catalyst through the asymmetric electrophilic substitution reaction of carboncations with indoles. The reaction can proceed in a very simple, clean, and atom-economical manner, bacause the only byproduct of the reaction was water. The method exhibited a broad generality. Excellent yields of over 90% as well as high enantioselectivity ranging from 35% to 96% ee were obtained for a rich range of both substrates. Finally, we present the determination of the absolute con?guration of chiral 2,3’-diindolylarylmethanes by using the combination of NMR spectroscopic and circular dichroism (CD) techniques. Namely, by condensation of a chiral 2,3’-diindolylarylmethane with the two enantiomers of (R)- and (S)-methoxyphenylacetic acid (MPA), respectively, we could obtain a pair of diastereoisomers. The proton chemical shifts and the favored conformers for each of the diastereoisomers were assigned by utilizing the combination of 1H-NMR, 1H-1H NOESY, 1H-13C HSQC, and 1H-13C HMBC spectroscopics. Consequently, the absolute con?guration of chiral 2,3’-diindolylarylmethanes could be determined on the basis of the observed differences in 1H NMR chemical shifts of the two diastereoisomers. Moreover, the CD analytical conclusion is entirely consistent with the previous determination of the absolute con?guration of chiral 2,3’-diindolylarylmethanes by NMR.The results would be useful for the future study of the effect of chirality on the bilogical activity of 2,3’-diindolylarylmethanes

Dithienopicenocarbazole as the kernel module of low-energy-gap organic dyes for efficient conversion of sunlight to electricity

An electron-donor with a polycyclic aromatic hydrocarbon dithieno-[2',3': 2,3; 3 '',2 '': 10,11] piceno[1,14,13,12-bcdefgh]carbazole (DTPC) as the primary skeleton and also decorated with multiple solubilizing groups is coupled to 4-(benzo[c][1,2,5]thiadiazol-4-ylethynyl) benzoic acid, for a metal-free organic dye (C281). The near-infrared photosensitizing dye exhibits over 80% external quantum efficiency in a broad spectral range from 480 nm to 735 nm, and a high power conversion efficiency of 13.0% under irradiance of simulated AM 1.5G sunlight (100 mW cm(-2))

Layer-Filter Threshold Technique for Near-Infrared Laser Ablation in Organic Semiconductor Device Processing

Although conventional laser ablation (CLA) method has widely been used in patterning of organic semiconductor thin films, its quality control still remains unsatisfied due to the ambiguous photochemical and photothermal processes. Based on industrial available near-infrared laser source, herein, a novel layer-filter threshold (LFT) technique is proposed, which involves the decomposition of targeted layer-filter and subsequent explosive evaporation process to purge away the upper layers instead of layer-by-layer ablation. For photovoltaic device with structure of metal/blend/PEDOT:PSS/ITO/glass, the PEDOT:PSS layer as the layer-filter is first demonstrated to be effective, and then the merged P1-P2 line and metal electrode layer are readily patterned through the self-aligned effect and regulation of ablation direction, respectively. The correlation between laser fluence and explosive ablation efficacy is also investigated. Finally, photovoltaic modules based on classical P3HT:PC61BM and low-bandgap PBDT-TFQ:PC71BM systems are separately fabricated following the LFT technique. It is found that over 90% of geometric fill factor is achieved while device performances maintain in a limited change with increased number of series cells. In comparison to conventional laser ablation methods, the LFT technique does not require sophisticated instruments but reaches comparable processing accuracy, which shows promising potential in the fabrication and commercialization of organic semiconductor thin-film devices

Intercorrelated Superhybrid of AgBr Supported on Graphitic-C3N4-Decorated Nitrogen-Doped Graphene: High Engineering Photocatalytic Activities for Water Purification and CO2 Reduction

AgBr nanoparticles supported on graphitic-C3N4-decorated nitrogen-doped graphene intercorrelated ternary superhybrid composites (ACNNG-x) acting as a novel visible-light driven photocatalyst are reported. Because of the fast interfacial charge separation and photoelectrochemical performance, the representative of ACNNG-50 superhybrid structure achieves high efficiency and stable photocatalytic capability for organic contaminant degradation and CO2 reduction

A simple and rapid colorimetric sensor for sulfide anion detection based on redox reaction of ABTS with Au (III)

A cost-effective and simple colorimetric sensor based on redox reaction of 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) with Au (III) ion, has been fabricated for the determination of sulfide (S2-) anion. In the proposed method, colorless ABTS could be oxidized by Au (III) to produce bluish green oxidized ABTS (oxABTS), accompanying with a dramatic absorption band centered at 414 nm. However, in the presence of S2-, Au (III) would be reduced to Au nanoparticles (Au NPs), Au2S NPs or their mixture, inducing a bluish green color fading of ABTS-Au (III) system and a decrease of the absorbance at 414 nm because neither Au NPs nor Au2S NPs were able to oxidize ABTS. Based on this phenomenon, detection of S2- was achieved via its inhibiting effect on the ABTS-Au (III) chromogenic reaction and carried out either by visualizing the solution color change or by measuring the absorbance change of the oxABTS. A linear relationship in the S2- concentration range of 0.5-15 mu M could be acquired with a low detection limit of 0.28 mu M with the help of UV-vis spectroscopy and 1.0 mu M by naked eyes. The as-proposed sensor showed high selectivity toward S2- over other common anions and metallic ions by taking advantage of the sulfide-specific reduction of Au (III). Additionally, such sensing system featured simplicity, rapidity and flexibility, with no requirement of organic probes or nanomaterials. The proposed sensor has been successfully applied to detect S2- in lake water samples with satisfactory results, demonstrating its potential application in environmental water sample detection. (C) 2015 Elsevier B.V. All rights reserved

Interconnected Co-Entrapped, N-Doped Carbon Nanotube Film as Active Hydrogen Evolution Cathode over the Whole pH Range

The use of electrocatalysts with low metal content (metal-deficient) or metal free for the hydrogen evolution reaction (HER) can prevent or decrease metal ion release, which reduces environmental impact; development of such catalysts with high activity and durability over the whole pH range is thus highly desired but still remains a huge challenge. Herein, we describe the direct growth of a film consisting of interconnected Co-entrapped, N-doped carbon nanotubes on carbon cloth using chemical vapor deposition from dicyanodiamine using a Co3O4 nanowire array as catalyst. This integrated architecture is used as a flexible 3D electrode for the electrolytic hydrogen evolution with outstanding catalytic activity and durability in acidic media. Moreover, this electrode is also highly efficient under neutral and basic conditions. It offers us an attractive carbon-based metal-deficient HER catalyst outperforming most transition-metal and all metal-free/deficient catalysts