金核-铂壳纳米修饰电极在酸性溶液中对甲醛的电催化氧化

制备了金(核)铂(壳)结构纳米粒子(Au@Pt-NPs)及其Au@Pt-NPs/PVP膜修饰电极,考察该修饰电极在酸性介质中对甲醛的电催化氧化行为,研究表明金和铂之闻存在协同催化作用.使Au@Pt纳米粒子比单独铂和金纳米粒子具有更高的催化活性.循环伏安行为显示修饰电极的氧化峰电流与溶液中甲醛浓度有良好的线性关系,线性范围为0.01-0.4mg/g、检出限为4ug/g,可作为甲醛的一种灵敏而快速的电化学检测方法.     

纳米Pt-Au合金修饰电极对鲁米诺电化学发光的增敏研究

用化学还原法制备了不同比例及不同粒径的纳米Au-Pt合金,并用UV-Vis、TEM、激光粒径、XRD等方法进行了表征,确认所合成物质确系双金属合金纳米粒子而非两种金属纳米粒子的混合物,通过改变合成方法和条件,可以得到一系列不同含量比和粒径,粒径范围在4.025~92.33 nm之间。采用电化学沉积法可将所制备合金修饰到铂盘电极上,在碱性介质(pH 12)中,随着合金比例的改变和合金粒径的减小,鲁米诺的电化学发光强度显著增强,当合金中Pt∶Au=6∶1,粒子粒径为最小时,所获得修饰电极上鲁米诺的电化学发光强度较裸电极增强近1个数量级。     

纳米MnO2对鲁米诺电化学发光的增敏作用

合成了纳米MnO2,考察了在碱性条件下将纳米MnO2添加到溶液体系中以及用溶胶-凝胶法修饰在铂电极上对鲁米诺的电化学发光(ECL)的影响,实验结果表明,在碱性条件下纳米MnO2在溶液体系中和修饰在铂片电极上对鲁米诺的电化学发光都有明显的增强作用.进一步研究了在纳米MnO2存在下,鲁米诺在铂片电极表面的固定,并制得电化学发光电极,获得良好性能.     

石墨烯-金纳米复合膜修饰电极溶出伏安法测定水中痕量汞

通过一步电沉积制备了石墨烯-金纳米复合膜修饰玻碳电极,并以此修饰电极为工作电极,采用差分脉冲阳极溶出伏安法测定环境水中痕量汞. 这种纳米复合膜结合了金纳米粒子和石墨烯两者的优势,能够增加异相电子转移速度和修饰电极对汞的富集能力,从而显著提高了电极的灵敏度和选择性. 这种修饰电极具有良好的分析性能：Hg(II)的分析曲线覆盖了0.2～5.0和5.0～30 μg/L两个线性范围,Hg(II)检测限(S/N=3)为0.030 μg/L. 此外,该修饰电极还表现出良好的稳定性和抗干扰性能,还被成功地应用于实际水样中Hg(II)的测定.     

电化学原位紫外可见反射谱用于表面等离激元效应的表征

在锁相放大技术的基础上,搭建了光检测系统与恒电位系统联用的电化学原位紫外-可见电反射光谱测量系统,并将其应用于表面等离激元体系的反射率表征。对光滑银电极和银纳米粒子修饰电极进行了电化学原位反射光谱测量,得到在不同电位下的反射光谱变化,发现在纳米粒子修饰电极上,产生强的反射谱峰。推测这种谱峰来自于纳米间隙结构造成的热点效应,电位可显著地调控纳米间隙结构的光散射效应。     

金纳米粒子修饰ITO玻璃电极对多巴胺的测定

利用自组装的方法制备了一种金纳米粒子修饰的ITO导电玻璃电极,采用扫描电镜、紫外可见光谱对该电极进行表征,用循环伏安法研究了该电极对多巴胺电化学行为的影响,得到该修饰电极能分开多巴胺和抗坏血酸的氧化峰.     

利用电化学微分质谱在燃料电池的阴极研究碳载体的氧化

利用电化学微分质谱,在双薄层流动电解池中,通过检测二氧化碳产物的信号研究氧气与铂纳米粒子对碳载体氧化机理与动力学的影响．研究发现,碳载体可以在不同的电位区间内被氧化;氧气可以加速碳的氧化,在相同的电位下碳氧化生成二氧化碳产物的速率在氧气饱和溶液中是在氮气饱和溶液中的两倍;铂纳米粒子可以催化碳的氧化,在碳电极上,担载的铂纳米粒子可以大大降低碳氧化的过电势．讨论了铂与氧气促进碳氧化的机理．     

双金属粒子在光–氢转换中的作用分析

本文采用两步阳极氧化法在TiO₂纳米环/管阵列表面负载Ag、Cu纳米粒子,与单金属修饰样品对比分析得到双金属对TiO₂光电响应和电极/电解液界面性质的影响。同时,XPS、UV-Vis和U-t测试表明AgCu-TiO₂光阳极金属抗氧化性强、可见光吸收好、光生电子寿命长,光电流密度达0.76 mA·cm^-2,对应产氢速率376μL·h^-1·cm^-2。对AgCu-TiO₂/H₂O、Ag-TiO₂/H₂O和Cu-TiO₂/H₂O体系进行分子动力学模拟计算,双金属体系相对较宽的耗尽层可促进光生电子–空穴分离、转移。最终结合热力学、动力学分析得到双金属修饰TiO₂光阳极的电子传输路径。     

过渡金属表面紫外线激发的表面增强Raman光谱(UV-SERS)研究

本文以紫外光325 nm作为激发线,成功获得了不同形貌的铂纳米粒子(铂纳米立方体和纳米絮状物),电化学粗糙的钴和镍电极在紫外区的表面增强拉曼散射(UV-SERS)效应。同时发现不同形貌的铂纳米结构在紫外区有不同的SERS效应,不同金属在紫外区的增强效应也不同,其中铂纳米立方体产生了最好的增强效应,这一结果也预示有必要发展更优的基底。为了利用UV-SERS研究具有重要应用意义的分子,同时也为了验证铂纳米立方体在紫外区的增强效应具有分子的普适性,我们研究了CO和腺嘌呤分子吸附在铂纳米立方体上的UV-SERS。     

金纳米粒子和钼氧化物复合膜修饰电极的制备及应用 (cited: 1)

利用循环伏安法将金纳米粒子和钼氧化物共同电沉积在玻碳电极表面,制备了金纳米粒子和钼氧化物复合膜修饰电极,利用SEM和XPS研究了MoO_x/AuNPs复合膜的表面形态,并研究其修饰电极对葡萄糖的电催化氧化过程. 首次提出了阳极扫描极化反向催化伏安法,即在反向扫描过程中纯的催化氧化电流通过扣减背景电流的方法被提取出来. 显著提高电流测量灵敏度改善了信噪比. 制备的MoO_x/AuNPs复合膜修饰电极在0.01～4.0 mmol/L对葡萄糖具有线性响应,电流灵敏度为2.35 mA·L/(mmol·cm²),检测限为9.01 μmol/L(信噪比为3).     

Nanostructured copper particles-incorporated Nafion-modified electrode for oxygen reduction

The electrocatalytic activity of nanostructured copper particles (represented as Cu_nano) incorporated Nafion (Nf) film-coated glassy carbon (GC) electrode (GC/Nf/Cu_nano) towards oxygen reduction was investigated in oxygenated 0.1 M phosphate buffer (pH 7.2). The electrodeposited Cu_nano in Nf film was characterized by atomic force microscopy (AFM) and X-ray photoelectron spectroscopy (XPS). The electrocatalytic activity of Cu_nano at the modified electrode towards oxygen reduction was studied using cyclic voltammetry technique. The molecular oxygen reduction at the GC/Nf/Cu_nano-modified electrode started at a more positive potential than at a bare GC electrode. A possible reaction mechanism was proposed in which oxygen reduction may proceed through two-step two-electron processes at the GC/Nf/Cu_nano electrode. The GC/Nf/Cunano electrode shows higher stability for oxygen reduction in neutral solution and the electrode may find applications in fuel cells.     

表面合金电催化剂上甲酸氧化的原位FTIR反射光谱研究

运用原位红外反射光谱(FTIRS)和电化学循环伏安法(CV)研究了甲酸在三种不同电极上的电催化特性。结果表明甲酸在碳载铂电极(Pt/GC)上的电催化氧化机理与本体铂电极(Pt)相类似,即可以通过活性中间体或毒性中间体氧化至CO_2。Pt/GC对甲酸的氧化比Pt具有更高的电催化活性。Pt/GC表面以Sb吸附原子修饰的电极(Sb-Pt/GC)上,甲酸氧化的起始电位(E;)提前至-0.10V,氧化电流峰电位(Ep)提前至0.34V,氧化峰电流(jp)值增加了7.28倍,半峰宽(FWHM)为0.30V。同样,Surface al-loy/GC电极上,E_I为-0.12V,E_p为0.32V和j_p为7.25mA·cm~(-2),相对Pt/GC分别负移了0.22,0.02V和增大了8.15倍,半峰宽(FWHM)为0.5V。表明Sb-Pt/GC和Surface alloy/GC电极不仅能够有效地抑制毒性中间体CO的生成,而且还可以显著地提高其对活性中间体的氧化的电催化活性。     

Quantifying the chiral magnetic effect from anomalous-viscous fluid dynamics

The Chiral Magnetic Effect(CME) is a macroscopic manifestation of fundamental chiral anomaly in a many-body system of chiral fermions, and emerges as an anomalous transport current in the fluid dynamics framework. Experimental observation of the CME is of great interest and has been reported in Dirac and Weyl semimetals. Significant efforts have also been made to look for the CME in heavy ion collisions. Critically needed for such a search is the theoretical prediction for the CME signal. In this paper we report a first quantitative modeling framework, Anomalous Viscous Fluid Dynamics(AVFD), which computes the evolution of fermion currents on top of realistic bulk evolution in heavy ion collisions and simultaneously accounts for both anomalous and normal viscous transport effects. AVFD allows a quantitative understanding of the generation and evolution of CME-induced charge separation during the hydrodynamic stage, as well as its dependence on theoretical ingredients. With reasonable estimates of key parameters, the AVFD simulations provide the first phenomenologically successful explanation of the measured signal in 200 AGe V Au Au collisions.     

Reciprocal and nonreciprocal magnetic linear birefringence in the γ-Dy<Subscript>2</Subscript>S<Subscript>3</Subscript> sesquisulfide

A study has been made of the spectral dependence of the Cotton-Mouton effect (CME) quadratic in magnetic field, nonreciprocal birefringence (NB) linear in magnetic field, and the Faraday effect (FE) in the cubic magnetic semiconductor γ-Dy₂S₃. Unlike the FE, the CME and the NB in this crystal are anisotropic, with the pattern of the anisotropy being dependent on the photon energy. The dependence of the CME and NB dispersion on the direction of the magnetic field B indicates contribution from a variety of electronic transitions and mechanisms to these phenomena. It is shown that the resonant contributions to the CME and NB in the transparency region originate from electronic transitions near E?3.4 eV (beyond the band edge E _g=2.8 eV), which are likely transitions from the localized ground state of the Dy³⁺ ion to states derived from mixing of the band and 4f ^N?1 5d states of the dysprosium ion. The character of the CME anisotropy in the transparency region and near the local electronic transition ⁶ H _15/2 → ⁶ F _3/2 connecting states of the unfilled 4f shell of the Dy³⁺ ion suggests the presence of a strong axial component of the crystal field acting on the rare earth ion.     

Thermal stability of sodium nitrate–sodium nitrite melts: A Raman spectra study

Abstract

A molten mixture of sodium nitrate–sodium nitrite is an important heat transfer and storage medium. It is important to research the thermal stability of such melts. In the present study, the equilibrium between nitrate and nitrite ion in sodium nitrate–sodium nitrite melts under air atmosphere was studied by Raman spectroscopy and the thermal stability of the melts was analyzed. The results show that when the temperature was greater than 644?K, for melts in which the weighted-in content of sodium nitrate is 90 mass %, the content of nitrate ion decreased slightly with temperature. However, for melts in which the weighted-in content of sodium nitrate was 10–80 mass %, the content of nitrate ion increased with temperature. Melts in which the weighted-in fraction of sodium nitrite were 15.22%, 14.71%, and 14.60% under air atmosphere showed optimal thermal stability at 644?K, 762?K, and 880?K, respectively. The findings of this study have provided a foundation for optimizing the composition of molten salts and for providing molten mixtures applicable to important industrial processes.     

Testing the chiral magnetic and chiral vortical effects in heavy ion collisions

We devise a test of the chiral magnetic and chiral vortical effects (CME and CVE) in relativistic heavy ion collisions that relies only on the general properties of triangle anomalies. We show that the ratio R(EB) = J(E)/J(B) of charge J(E) and baryon J(B) currents for CME is R(EB)(CME) → ∞ for three light flavors of quarks (N(f) = 3), and R(EB)(CME) = 5 for N(f) = 2, whereas for CVE it is R(EB)(CVE) = 0 for N(f) = 3 and R(EB)(CME) = 1/2 for N(f) = 2. The physical world with light u,d quarks and a heavier s quark is in between the N(f) = 2 and N(f) = 3 cases; therefore, the ratios R(EB) for CME and CVE should differ by over an order of magnitude providing a possibility to separate clearly the CME and CVE contributions. In both cases, there has to be a positive correlation between the charge and baryon number asymmetries that can be tested on the event-by-event basis.     

三波长光度法测定微量亚硝酸根及其机理的研究

本文研究了硫堇与亚硝酸根的反应 ,根据三波长处吸光度的加和值与亚硝酸根浓度的线性关系 ,提出并建立了测定亚硝酸根含量的新方法 ,线性范围 0～ 0 .5 6 0 m g· L- 1 ,用于样品中亚硝酸根的测定获得满意结果。并对反应机理进行了初步探讨     

基于亚硝化反应分光光度法测定亚硝酸根

本文研究了在酸性介质中吖啶红与亚硝酸根发生亚硝化褪色反应的条件 ,建立了光度法测定亚硝酸根的新方法。最大吸收波长 5 2 5nm处的ΔA与亚硝酸根浓度在 0 0 2 5～ 0 5 μg·mL-1范围内成线性关系。用于水中NO-2 的测定 ,结果满意。     

紫外分光光度法测定肉制品中亚硝酸盐

在酸性条件下 ,亚硝酸盐与间苯二酚及锆氧离子反应生成有色螯合物 ,建立了一种简易快速的测定食品中微量亚硝酸盐的方法。优化了波长、酸度、显色剂用量、显色时间等实验条件 ,并由正交实验进一步验证。对猪肉、午餐肉、腊肠、香肠几种样品中的亚硝酸根离子进行测定 ,回收率达 90 %以上     

Electrodeposition of platinum on tourmaline and application as an electrocatalyst for oxidation of methanol

A composite electrode of Pt nanoparticles coupled with tourmaline is prepared on glassy carbon (GC) disk electrode via electrodeposition. The nanocomposite of Pt/tourmaline is characterized by scanning electron microscopy, X-ray photoelectron spectroscopy, X-ray powder diffraction, and transmission electron microscopy examinations linked with energy dispersive X-ray analysis. The electrocatalytic performance of the composite electrode (Pt/tourmaline/GC) is investigated in electrocatalysis oxidation of methanol at room temperature by cyclic voltammetry and chronoamperometry. It is indicated that Pt nanoparticles with size of ∼5 nm are uniformly assembled along the tourmaline particles and Pt exists in metallic and oxidated states confirmed by XPS. The results of electro-oxidation of methanol show that Pt/tourmaline catalyst is catalytically more active and stable than platinum-modified GC electrode, and the onset potential of Pt/tourmaline shifts 0.15 V to the negative side, and also the current density is significantly enhanced.