磷钼杂多酸修饰电极催化还原测定IO_3~-与BrO_3~-的液相色谱电化学研究

本文介绍了1:12磷钼杂多酸(PMo_(12))修饰电极的制备及其对IO_3~-、BrO_3~-的催化还原作用。本文还研究了在涂敷十六烷基三甲基溴化铵的C_(18)键合固定相上IO_3~-与BrO_3~-的分离方法,并采用修饰电极色谱电化学的方法对IO_3~-与BrO_3~-进行定量测定。IO_3~-、BrO_3~-的量分别在8.0×10(-10)～1.0×10~(-7)mol和1.6×10~(-9)～3.0×10~(-7)mol范围内与峰高呈良好的线性关系,检测限分别为4.0×10~(-10)mol与1.0×10~(-9)mol。用本方法测定IO_3~-和BrO_3~-重现性好、线性范围大,是测定IO_3~-与BrO_3~-的一种实用方法。     

基于碳纳米管/聚中性红复合物膜的溴酸盐电化学传感研究

BrO_3~-由于其氧化特性已在面包制作过程中作为面粉发酵的食品添加剂被广泛使用,并且通常在饮用水中作为臭氧消毒的副产物被发现.然而实验证明BrO_3~-能导致肾脏细胞肿瘤、腹膜的间皮瘤,并且通过长期追踪饮用含BrO_3~-的水的实验鼠发现,还能导致甲状腺的小囊细胞肿瘤.另有报告称,无论在生物体内和体外,BrO_3~-都会导致染色体失常和微核的形成.另外,在动物和人的听觉方面,BrO_3~-的副作用也已被证实.本实验通过NR在MWNTs修饰的GC电极上的电聚合制备了MWNT/PNR复合物修饰电极.由于PNR对BrO_3~-还原的良好的电催化能力和MWNTs独特的物化性质,这种基于GC/MWNT/PNR电极的BrO_3~-传感器表现出了优越的响应信号和传感性能.     

D301和MIEX两种阴离子交换树脂对水中BrO3-的吸附性能

研究了D301和MIEX两种阴离子交换树脂对水中BrO_3~-的吸附性能。结果表明:pH值对两种树脂吸附BrO_3~-的影响相似,两种树脂均在pH为4～9范围时对BrO_3~-的吸附量最大。共存Cl~-、SO_4~(2-)和NO~-_3明显削弱两种树脂对BrO_3~-的吸附,其影响大小顺序为NO~-_3SO_4~(2-)Cl~-。MIEX树脂吸附BrO_3~-仅需4 min达到平衡,D301树脂吸附BrO_3~-需180 min达到平衡,MIEX树脂具有比D301树脂更大的准二级速率常数K_2和颗粒内扩散速率常数K_(id)。BrO_3~-在D301和MIEX两种树脂上的吸附等温线符合Freundlich方程,MIEX树脂对BrO_3~-的吸附量大于D301树脂对BrO_3~-的吸附量。D301和MIEX两种树脂对BrO_3~-的吸附机理为阴离子交换。     

SiW_(12)/g-C_3N_4纳米复合材料的制备及光催化活性

采用浸渍法成功地将硅钨酸(SiW_(12))负载到g-C_3N_4表面,制备出一种新型的SiW_(12)/g-C_3N_4复合光催化剂.通过X-射线衍射(XRD)、红外光谱(FT-IR)、扫描电子显微镜(SEM)、荧光光谱(PL)和紫外-可见分光光度计(UV-Vis)等测试手段对其结构和性能进行表征.光催化实验表明,在可见光照射下(λ420nm),SiW_(12)/g-C_3N_4复合材料表现出比纯gC3N4更高的光催化性能.其中,SiW_(12)/g-C_3N_4(质量比为1∶3)复合材料具有最好的光催化活性,在可见光下辐照120 min时,RhB的脱色率达98.0%.若加入H_2O_2(2 mL,质量分数为30%)进行修饰,仅在可见光下辐照24min,RhB的脱色率就达到97.7%.SiW_(12)/g-C_3N_4复合材料光催化活性的提高归因于光生电子-空穴对的有效分离.此外,由H_2O_2分解产生的氢氧自由基(·OH)也起到了至关重要的作用.     

水系体系中CO2在稀土(Nd)(Ⅲ)双酞菁修饰电极上的电催化还原研究

探讨了CO_2在稀土(Nd)(Ⅲ)双酞菁修饰电极上的电催还原行为。通过滴涂法将稀土(Nd)(Ⅲ)双酞菁担载在玻碳电极上制备成它的修饰电极,在水溶液中利用循环伏安、红外光谱法等方法研究制备的修饰电极对CO_2的电催化还原性能。结果表明,所制备的稀土(Nd)(Ⅲ)双酞菁修饰电极对CO_2的电催化还原有较高的活性,还原电流随修饰量增加而变大,修饰电极的还原电流与溶液的pH值有关,随着pH值变大,还原峰向负方向移动。实验结果表明,稀土(Nd)(Ⅲ)双酞菁修饰电极对二氧化碳电化学还原具有很好的电催化活性,在该修饰电极上,CO_2可在较正的电位下被还原。     

一维纳米Co_3O_4,Ag/Co_3O_4及CuO/Co_3O_4的合成与电催化性能(英文)

采用水热合成法制备了Co3O4及复合Ag/Co3O4、CuO/Co3O4一维纳米产品。用XRD,FE-SEM和TEM手段对产品进行了表征。采用循环伏安法研究了合成产品修饰的玻碳电极在碱性溶液中对对硝基苯酚的电催化还原性能。与裸玻碳电极相比,1mmol·L-1的对硝基苯酚在用Co3O4、特别是CuO/Co3O4修饰的玻碳电极上还原的峰电流明显增大,用Ag/Co3O4(Ag/Co原子比分别为1∶5和2∶5)修饰的玻碳电极催化还原对硝基苯酚时,尽管还原峰电流增大不是太大,但其峰电位明显降低(分别降低0.265和0.371V)。     

甘氨酸修饰的Pt(111)电极上的氧还原

利用单晶旋转圆盘电极技术（Hanging Meniscus Rotating Disk Electrode,　HMRD）在硫酸和高氯酸溶液中分别研究了甘氨酸修饰的Pt(111)电极表面氧分子的电催化还原反应. 实验发现：在硫酸溶液中,经甘氨酸修饰的Pt(111)电极表面的氧还原活性明显提高,其中氧还原的半波电位与Pt(111)电极的相比正移约0.1 V,而在高氯酸溶液中,甘氨酸修饰的Pt(111)电极的活性几乎没有发生变化. 该实验结果表明：甘氨酸修饰的Pt(111)电极一方面抑制了SO₄^2-在电极表面的吸附,另一方面又能在电极表面提供相邻的空位供氧分子吸附. 通过与文献中报道的CN^-修饰的Pt(111)电极上的氧还原结果的对比,可以推测甘氨酸修饰的Pt(111)电极表面氧还原活性提高是由于甘氨酸在Pt(111)表面可能先被氧化成CN^-后吸附在电极表面,进而促进了氧分子的电催化还原反应.     

Ti_(100-δ)Cu_δ(δ=0.02,0.28,1.39,5.65)阴极的制备及电催化还原NO_3~-机理

以Ti板为基体,采用异位电沉积法通过调控电镀时间制备了质量分数(δ)分别为0.02,0.28,1.39和5.65的Ti_(100-δ)Cuδ阴极;利用扫描电子显微镜(SEM)、X射线衍射(XRD)、电化学测试及NO_3~-处理实验等手段对其微观形貌、物相组成、电催化活性、抗腐蚀性能和产物选择性等进行了表征.结果表明,δ≥0.28时Ti_(100-δ)Cuδ电极表面的Cu镀层呈现(111)晶面择优取向,可有效提高电极稳定性;Cu活性层的形成为NO_3~-的吸附提供了活性点位,增强了电极的电催化性能,但Cu的加入会降低电极抗腐蚀性能;在一定的载铜量范围内,单质Cu对NO_3~-降解产物NO-2的吸附有一定的抑制作用,但会增强NO-2的还原反应活性,提高N2选择系数.应用Ti_(100-δ)Cuδ(δ=5.65)阴极在电流密度为20 m A/cm2、电解时间6 h条件下对NO_3~-进行处理,结果表明,NO_3~-去除率和N2选择系数分别高达75.47%和32.65%,与Ti电极的NO_3~-去除率(39.89%)和N2选择系数(2.19%)相比有显著提高.     

[SiMn(H2O)W11O39]6-在玻碳电极上的多层组装膜修饰电极及电化学行为

采用电化学生长法制备包含杂多酸[SiMn(H2O)W11O39]6-(SiMnW11)和聚合物阳离子PDDA的多层膜修饰电极,利用循环伏安法研究其电化学行为、扫描速率的影响及其对BrO3-和NO2-体系还原的电催化性能.结果表明:SiMnW11多层膜增长均匀,峰电流随层数的增加而增加;多层膜的峰电流随扫速的增加而增加;SiMnW11修饰电极对BrO2-和NO2-的还原具有良好的电催化作用.在最佳的实验条件下,BrO3-的还原峰电流与其浓度在0.345～5.28 mmol·L-1范围内呈良好的线性关系,相关系数r=0.998,检出限8.8×10-5mol·L-1.     

聚吡咯对Cu(II)的催化还原作用

以对甲苯磺酸钠为掺杂剂在不锈钢(SS)电极表面恒电位合成聚吡咯(PPy)修饰膜, 采用恒电位和动电位对Cu(II)的还原效果进行了研究, 并与不锈钢电极进行了对比. 结果表明, 由于聚吡咯的催化作用, 聚吡咯修饰电极对Cu(II)还原效率高于不锈钢电极; 聚吡咯膜对析氢有明显的抑制作用, 因此电流效率远远高于不锈钢电极, 这是采用聚吡咯进行电化学还原的明显优势. 通过在不同浓度Cu(II)酸性溶液中的循环伏安行为讨论了聚吡咯对Cu(II)的还原作用机理.     

Assembly and Electrochemical Study of Transition Metal Substituted Polyoxometalates SiW11NiO6-39 and SiW11MnO6-39 on 4-Aminothiophenol Modified Glassy Carbon Electrode

Via layer-by-layer assembly, the polyoxometalates of Keggin type, SiW11O39Ni(H2O)6-(SiNiW11) and SiW11O39Mn(H2O)6-(SiMnW11) were first immobilized on a 4-aminothiophenol(4-ATP) modified glassy carbon electrode surface. The electrochemical behavior of these polyoxometalates was investigated. They exhibited some special properties in the films, which are different from those in a homogeneous aqueous solution. Their reaction mechanism in a multilayer film is proposed. The electrocatalytic behavior of these multilayer film electrodes for the reduction of BrO-3 and NO-2 were comparatively studied.     

Layer-by-layer assembly of silicotungstate multilayer films modified on glassy carbon electrode and their electrochemical behaviors

A new electrode was modified by multilayer films composed of heteropolyanion (SiW12) and cationic polymer poly(diallyldimethylammonium chloride) through electrochemical growth. The modified electrode electrochemical behavior, the effect of solution pH and electrocatalytic response to the reduction of BrO3- and NO2- have been investigated. The result shows that the electrochemical process of multilayer films modified electrode including SiW12 is a reversible process by electrochemical step. One-electron process has no proton participation in the first step, and one-electron process is accompanied by one proton participation in the second step and two-electron process is accompanied by two protons participation in the third step. The films grow uniformly, and the peak currents increase with increasing layer numbers. The peak currents increase with scan rate, and the reduced potentials of multilayer films shift negatively with increasing pH. The electrochemical mechanism of multilayer films was suggested.     

TiO2-WO3负载硅钨酸盐聚苯胺膜电极的电化学行为及电催化性能研究

用循环伏安法制备了金属氧化物(TiO2-WO3)负载硅钨酸盐聚苯胺膜修饰玻碳电极(PAn/SiW12/TiO2-WO3/GC),优化了聚合条件,并对该化学修饰电极的电化学行为,包括溶液pH值的影响和电极的稳定性等进行了研究。研究结果表明,此修饰电极聚合物膜不但保持了该杂多酸的电化学活性和电催化性能,又具有良好的稳定性。在0.5 mol/LH2SO4溶液中,该膜电极中的SiW12的第2个还原峰对BrO3-有很好电催化活性,催化过程符合EC平行催化机理。     

[SiNi(H2O)W11O39]6-多层组装膜修饰电极及其电化学行为

采用电化学生长法制备包含杂多酸[SiNi(H2O)W11O39]6-(SiNiW11)和聚合物阳离子PDDA的多层膜修饰电极, 利用循环伏安法研究其电化学行为、 pH的影响及其对BrO3-和NO2-体系还原的电催化性能;并对多层膜电化学过程机理进行了初步探讨. 结果表明: 多层膜的增长均匀, 峰电流随层数的增加而增加;多层膜的峰电流随扫速的增加而增加;还原峰的峰电位随pH的增加而负移.     

钒取代多金属氧酸盐/聚酰胺-胺多层膜的制备及其电催化性能

用层接层自组装的方法制备了过渡金属钒取代的多金属氧酸盐PMo11VO4-40/聚酰胺-胺多层纳米复合膜. X射线光电子能谱(XPS)、紫外-可见光谱(UV-Vis)、循环伏安(CV)测定和分析结果表明, PMo11VO4-40和聚酰胺-胺通过静电相互作用形成了纳米交替多层膜,且膜的增长均匀. 复合膜的循环伏安图呈现出四对氧化还原峰(一个V的单电子和三个Mo的双电子), 峰电流与扫描速率成正比, 其式量电位随着pH 的增加而线性负移, 表明电极过程属于表面控制过程, 电荷传递很快且有氢离子参与多金属氧酸盐的氧化还原反应. 该方法制备的多层膜修饰电极稳定性好, 对NO-2、BrO-3及H2O2具有良好的催化还原活性.     

Fabrication of Covalently Attached Multilayer Film Electrode Containing Iron Porphyrin and Its Electrocatalysis Toward Sulfite

Construction of a highly stable covalently attached multilayer film electrode containing iron porphyrin was achieved by UV irradiation of ionic self‐assembled multilayer films of diazo‐resins (DAR) and anionic Fe(III)tetrakis(p‐sulfonatophenyl)porphyrin (FeTSPP). The multilayer films had been characterized by UV, IR spectra and cyclic valtammetry. The electrocatalytic transformation of sulfite to SO₄^2? by the multilayer film electrode containing FeTSPP was investigated. In 0.1 M NH₄OH? NH₄Cl buffer solution (pH 8.74) and 0.1 M borate buffer solution (pH 9.18) the electrocatalytic oxidation of sulfite through the multilayer film electrode can be performed. However, in acetate buffer solution (pH 4.0) the electrocatalytic reduction of sulfite by the multilayer film electrode had also good activity. The modified electrode also exhibited a fast response and good stability.     

Alternate assemblies of platinum nanoparticles and metalloporphyrins as tunable electrocatalysts for dioxygen reduction

Through electrostatic layer-by-layer (LBL) assembly, negatively charged citrate-stabilized platinum nanoparticles (PtNPs) and positively charged [tetrakis(N-methylpyridyl)porphyrinato] cobalt were alternately deposited on a 4-aminobenzoic acid-modified glassy carbon electrode and also on indium tin oxide substrates, directly forming the three-dimensional nanostructured materials. Thus-prepared multilayer films were characterized by UV--visible spectroscopy, surface plasmon resonance (SPR) spectroscopy, atomic force microscopy (AFM), and cyclic voltammetry. Regular growth of the multilayer films is monitored by UV--visible spectroscopy and SPR spectroscopy. AFM provides the morphology of the multilayer films. The PtNPs containing multilayer films exhibit high electrocatalytic activity for the reduction of dioxygen with high stability. Rotating disk electrode voltammetry and rotating ring-disk electrode voltammetry demonstrate that the PtNP-containing multilayer films can catalyze an almost four-electron reduction of O(2) to H(2)O in an air-saturated 0.5 M H(2)SO(4) solution. Furthermore, the electrocatalytic activity of the films could be further tailored by simply choosing different cycles in the LBL process or more specifically the amount of the assembly components in the films. The high electrocatalytic activity and good stability for dioxygen reduction make the PtNP-containing multilayer films potential candidates for the efficient cathode material in fuel cells.     

Multilayer films of cationic surfactants incorporating polyoxometalate on electrodes

A new kind of multilayer of didodecyldimethylammonium bromide (DDAB) and 1:12 phosphomolybdic anions (PMo₁₂) was achieved on the surface of a wax-impregnated graphite (WIG) electrode by ion exchange and electrostatic interaction. The characterization and electrochemical behavior of the multilayer films of DDAB/PMo₁₂ is described in detail. The chemically modified electrode was shown to exhibit an excellent electrocatalytic activity toward the reduction of BrO₃ ^– anion in 0.5 M H₂SO₄ and possesses several attractive features, such as simple preparation, fast response, good stability, etc. Electronic Publication     

卟啉-金属氧簇超分子化合物的光谱及电催化氧还原

应用紫外可见吸收光谱研究了meso 四(4 N 苄基吡啶基)卟啉(MTBPyP4＋,M=H2,Zn)阳离子与金属氧簇阴离子(SiW12O4－40)在水溶液中的光谱行为. 光谱演变及Job图表明MTBPyP4＋与SiW12O4－40在水溶液中可形成稳定的1∶1的超分子化合物. 同时本文还考察了化学计量为1∶1的[CoTBPyP][SiW12O40]超分子化合物的电催化分子氧还原行为, 表明该类超分子化合物有望成为一类新的催化氧还原的修饰电极材料.     

Electrochemistry of ITO electrode modified by multilayer ultrathin films based on crown-shaped polyoxomolybdate

The electrochemical multilayer films of crown-shaped polyoxomolybdate Na21{[Na5(H2O)14] intersection[Mo(V)(20)Mo(VI)(26)O134(OH)10(mu-CH3COO)4]}.CH3COONa.90H2O (Mo46) and polyelectrolytes by layer-by-layer assembly were investigated. The stable multilayer films were assembled by alternate adsorption of negatively charged POM and positively charged polyelectrolytes is from their aqueous dispersions. UV-vis spectroscopy and cyclic voltammetry were used to monitor the regular growth of the multilayer films. The multilayer films-modified ITO electrode was used for the detection of electrocatalytic activity toward the reduction of nitrite, bromate, and hydrogen peroxide. The proposed novel immobilized method exhibited good stability, reproducibility and high sensitivity for the determination of electrocatalytic, which is important for practical application.