Dynamics of anodic process of gold electrode in thiourea solution in the presence of sulfur dioxide

1　INTRODUCTIONCyanidefreetechnologyofgoldextractionisanimportantissueinhydrometallurgy[1,2 ] .Thioureawasusedasanimportantmetallurgicalreagentduetoitsgoodselectivity ,low poisonousnessandhigheffi ciency[3,4 ] .Refs .[5 7]showedthatanodedissolv ingofgoldwillbeacceleratedifsulfurousacidorsul furdioxide (H2 SO3)isaddedintothioureasystem .Themechanismwasconsideredthatsulfurousacidwasinvolvedintotheelectrochemistryreactionofthesystem ,mainlyacceleratingdeoxidizationreactionofformamidinedisul…     

Electrochemical oxidation of pyrrhotute in aqueous solution

The anodic surface oxidation of natural pyrrhotite in 0.3 mol/L KCI and HCI solution （pH 4.0） and 0.1 mol/L Na2B4O7 solution （pH 9.18） respectively was investigated by using cyclic voltammetry, Tafel plot, and chronoamperometry. In 0.3 mol/L KCl and HCl solution （pH 4.0）, at potential less than 0.5 V（vs SHE）, the production of anodic oxidation on pyrrhotite surface can not maintain a stable phase to form a passive film. In 0.1 mol/L Na2B4O7 solution （pH 9.18）, when the electrode potential increases to more than 0.5 V （vs SHE）, part of S is oxidized to sulfate, making the passive film somewhat porous, but elemental S and metal oxidates Fe（OH）3 still remain on the electrode surface, and the passive film can not be broken down totally. According to PARCalc Tafel analysis, the corresponding corrosion current density （J0） is 5.34 μA/cm^2 , which is also the exchange current density of the oxidation reaction on pyrrhotite electrode surface in 0. 1 mol/L Na2B4O7 solution （pH 9. 18）. The electrochemical dynamics equation of the oxidation was determined.     

Si/BDD电极在酸/碱电解条件下的电化学氧化性能变化

目的 探究Si/BDD电极在酸性、碱性2种电解条件下的性能变化特征,阐明BDD电极在酸、碱溶液中电化学氧化性能的变化与失效机理。方法 通过HFCVD技术制备Si/BDD电极,分别在1 mol/L H₂SO₄、1 mol/L NaOH溶液中进行加速寿命实验,以活性蓝19(RB-19)模拟染料废水,进行电化学氧化降解实验。使用扫描电子显微镜、拉曼光谱、接触角测试仪、紫外分光光度计及电化学工作站对电极的表面形貌、成分及电化学性能进行表征。结果 在1 mol/L NaOH溶液中,当电解时间为195 h时,电极表面部分区域发生了明显的脱落现象;在1 mol/L H₂SO₄溶液中,当电解时间达到600 h时,电极表面仍未出现明显的脱落现象,电极表面形貌由清晰转为模糊,晶粒尺寸细化,且在晶界处存在明显的腐蚀现象;在酸溶液中,BDD电极对RB-19的降解效果随着电解时间的延长而提高,而在碱溶液中,其降解效果与电解10 h的降解效果基本一致。结论 与酸溶液相比,Si/BDD电极更易在碱溶液中发生腐蚀。     

亚硫酸钠在碱性硫脲溶金体系中的电化学行为

用电化学工作站测试金电极和铂电极的极化曲线和交流阻抗,研究亚硫酸钠对碱性硫脲溶解金的影响。结果表明,亚硫酸钠对金的腐蚀电位(E_(corr))为-0.776 V,远低于硫脲,腐蚀速率为0.014mm/a,是有效的溶金试剂;在铂电极上测试,硫脲在碱性条件下会发生不可逆氧化分解,但亚硫酸钠对硫脲的氧化分解没有明显抑制作用;当硫脲中添加亚硫酸钠后,E_(corr)降低,腐蚀速率增大,电化学阻抗弧值大大降低,协同促进金的溶解;0.15 mol/L硫脲+0.15 mol/L亚硫酸钠的溶液具有最佳溶金效果。     

Surface modification of indium tin oxide films with Au ions implantation: Characterization and application in bioelectrochemistry

Indium tin oxide (ITO) thin film coated glass substrates have been implanted with 21 keV Au ions at a fluence of 1.0 × 10¹⁷ ions/cm² at room temperature. The resulting gold film was characterized with X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), scanning electron microscopy (SEM), UV-Vis spectra and electrochemical methods. The results reveal that the implanted Au atoms were in the zero-valent metallic state and these Au atoms precipitated to form nanoclusters on the ITO surface whose average radius was estimated between 2 and 5 nm. The preferentially growing orientation was Au (111) plane during the formation process of gold film and the value of gold active surface area normalized by the geometric electrode areas was 0.48 for Au ion implanted ITO (Au/ITO) electrode. The potential utility of Au/ITO films was investigated. The Au/ITO electrode exhibited effective catalytic responses towards biomolecules such as ascorbic acid (AA) oxidation and lowered oxidation potential of AA by 0.6 V when compared with the bare ITO electrode. Myoglobin (Mb) was also successfully immobilized on the Au/ITO electrode and the direct electron transfer between proteins and electrode surface was realized. It was demonstrated that the Au/ITO film offered a favorable microenvironment for the orientation of biomolecules. New biomaterials with specific electrocatalytic and electrochemical features could be fabricated using this method.     

金修饰纳米多孔Pd催化剂对甲酸氧化的电催化活性

以水热法制备出纳米多孔网状钯催化剂(nanoPd),采用电位扫描在其上沉积金,制成金修饰纳米钯电极(Au/nanoPd),运用循环伏安法(CV)、线性扫描(LSV)和交流阻抗谱(EIS)比较nanoPd和Au/nanoPd电极对甲酸氧化反应的电催化活性。CV和LSV结果表明:金在nanoPd表面的沉积促进钯对甲酸氧化的电催化活性,起始电位提前,电流密度更高。EIS研究结果也表明:在Au/nanoPd电极上,甲酸氧化反应的电荷传递电阻更低。结果表明:金修饰纳米钯电极(Au/nanoPd)对甲酸氧化具有较高的电催化活性。     

DISSOLUTION THEORY OF GOLD IN ALKALINE THIOUREA SOLUTION(Ⅱ)——Electrochemical Study on Au-Fe Mix Anode in Alkaline Thiourea Solution Containing Na_2SO_3

１ＩＮＴＲＯＤＵＣＴＩＯＮＭａｎｙｓｔｕｄｉｅｓｏｎｔｈｅｅｘｔｒａｃｔｉｏｎｏｆｇｏｌｄｆｒｏｍｏｒｅｏｒｓｃｒａｐｗｉｔｈｔｈｉｏｕｒｅａｗｅｒｅｒｅｐｏｒｔｅｄ［１－３］，ｂｕｔａｌｔｈｏｓｅｗｅｒｅｌｉｍｉｔｅｄｏｎｌｙｉｎａｃｉｄｉｃｍｅｄ...     

Au-Pt双金属纳米粒子的制备及其电催化性质

在PEG10000/Vc/HAuCl4体系中,用Vc还原HAuCl4制备金纳米粒子,以所制备的金纳米粒子为晶种,通过控制HAuCl4与H2PtCl6的质量比,制备不同Pt/Au比的双金属纳米粒子,并进一步研究其对H2O2电化学氧化的催化作用。紫外-可见光谱(Uv-vis)、透射电子显微镜(TEM)、选区电子衍射(SAED)、X射线粉末衍射(XRD)等实验结果表明：Au-Pt双金属纳米粒子为面心立方结构的合金。用循环伏安法对Au-Pt双金属纳米粒子修饰的玻碳电极的电化学性能进行测试,结果表明：Au-Pt双金属纳米粒子对H2O2电化学氧化有一定的催化作用。催化效率随Au-Pt双金属粒子中Pt含量的增加而增加。     

硼掺杂金刚石厚膜电极对高浓度工业废水的降解实验研究

目的 探索BDD厚膜电极处理高浓度有机废水方案的可行性.方法 利用直流电弧等离子体喷射法制备BDD厚膜电极,对其结构和电化学性能进行表征,并利用BDD厚膜作为电解阳极对高浓度模拟废水(葡萄糖溶液)和实际工业过程产生的橡胶助剂废水进行电化学氧化处理.结果 对电极样品的表征表明,其在0.5 mol/L H2SO4溶液中的电化学窗口和析氧电位分别为3.02 V和2.07 V.对模拟废水(葡萄糖溶液)和橡胶助剂工业废水的电化学降解实验表明,BDD厚膜电极对废水中的有机物有很好的去除效果.对于初始COD(化学需氧量)值为18940 mg/L的高浓度葡萄糖溶液,在电解8 h后,COD值的去除率为91.02％.对于初始COD值为18380 mg/L的高浓度橡胶助剂废水,在电解10 h后,COD值的去除率为97.42％.结论 直流电弧等离子体喷射法制备的重掺杂BDD厚膜电极有着较宽的电化学窗口和高的析氧电位,能有效地降低有机溶液的COD值.BDD厚膜电极的最佳工作条件为:在高有机物浓度环境下,为提高降解效率,应选择较高的电流密度.对于高COD值葡萄糖溶液和橡胶助剂废水,最优电流密度为200 mA.在低有机物浓度环境下,为降低能耗,应该选择较低的电流密度.对于低COD值葡萄糖溶液,最优电流密度为50 mA.     

表面处理对储氢合金电化学性能的影响研究

通过电化学方法,研究了储氢合金碱化处理及碱液中加入KBH4对合金电极的电催化活性和高倍率放电性能的影响.结果表明:处理后合金颗粒分布均匀,表面变得粗糙.两种处理方法均增加了合金表面的电催化活性,降低了合金电极的极化电阻,从而提高了高倍率放电能力.尤其在900mA/g放电时,处理前合金电极不能放电,单一碱处理合金电极和加入还原剂碱处理合金电极仍具有较高的高倍率放电能力,分别为69.2%和83.4%.在单一碱溶液中加入还原剂KBH4处理后,合金电极的电化学性能明显高于单一碱处理合金电极.     

钛基RuO2-Ta2O5涂层电极材料的电容性能分析

采用热分解方法在钛基体上制备了(36%)RuO2-(64%)Ta2O5混合氧化物涂层。采用X射线衍射(XRD)、扫描电镜(SEM)、循环伏安(CV)以及恒流充放电测试研究了涂层电极的组织结构、表面形貌以及电容性能。结果表明:(36%)RuO2-(64%)Ta2O5涂层以非晶氧化物为基体,带有少量纳米微晶RuO2的组织结构。在酸性溶液中,在50～900 mV/s的扫描速度下,Ti/(36%)RuO2-(64%)Ta2O5涂层电极的伏安曲线都具有近似矩形形状,表现出良好的电容特性和功率特性。以5 mA/cm2和10 mA/cm2放电,比电容分别为525.5 F/g和495.1 F/g。在经历2000次循环充放电后,电极的电荷储存能力仍未衰减,显示其优异的循环稳定性。     

指数律衰减电流极化电位响应的解析及其在测定金属的瞬时腐蚀速度方面的应用

本文为适应腐蚀体系中受力试样的腐蚀速度快速测定,对指数律衰减电流的电位响应进行了研究,从理论上导出指数律衰减电流极化的电位响应曲线上有极值点存在,这是用指数律衰减电流极化极值法测定金属腐蚀速度的理论基础。本文把用此方法和稳态方法得出的结果进行了比较,表明两种方法测得的结果比较接近,同时列出了321不锈钢在0.5mol/LHCI+0.5mol/LNaCl体系中不同应力水平时的瞬时腐蚀速度。     

Electrochemical polymerization of pyrrole in BMIMPF6 ionic liquid and its electrochemical response to dopamine in the presence of ascorbic acid

Polypyrrole (PPy) film modified glassy carbon (GC) electrode was prepared by electrochemical polymerization in 1-butyl-3-methylimidazolium hexafluorophosphate (BMIMPF₆) room temperature ionic liquid. The PPy film obtained in ionic liquid adhered on the electrode surface well and the properties of the PPy film have been characterized via UV–vis spectra and scanning electron microscopy (SEM). The electrochemical response of the PPy modified electrodes toward ascorbic acid (AA) and dopamine (DA) was investigated by differential pulse voltammetry (DPV). Well separated anodic peaks were observed at PPy electrode with peak separation (ΔE) of 200 mV at pH 6.2. Compared with PPy electrode prepared in aqueous solution, DA has a higher oxidation currents at the modified electrode prepared in ionic liquid. The oxidation peak potentials and currents were affected by the pH valuation and the film thicknesses.     

LiNi_(0.5)Mn_(0.5)O_2电极在LiNO_3电解液中的电化学性能及循环衰减机理(英文)

研究LiNi0.5Mn0.5O2电极在LiNO3水溶液中的电化学行为,同时分析该电极在不同pH值电解液中的循环衰减原因。循环伏安测试显示LiNi0.5Mn0.5O2在浓度为5 mol/L的LiNO3水溶液中具有较好的锂离子脱嵌能力。对比发现,LiNi0.5Mn0.5O2电极在浓度为5 mol/L,pH值为12的LiNO3水溶液中具有最好的循环稳定性能。通过交流阻抗法、X射线衍射分析及电极形貌的对比分析发现:电极在浓度为5 mol/L,pH值为12的LiNO3水溶液中循环时,电极的表面形貌和电极结构都能得到较好的保持,电极的电荷传递阻抗得到明显抑制,因此在该pH值电解液中的循环稳定性最好。     

硼掺杂金刚石电极降解活性橙X-GN偶氮染料废水的研究

目的研究硼掺杂金刚石(BDD)电极电化学氧化降解活性橙X-GN偶氮染料废水。方法采用热丝气相沉积法(HFCVD)制备铌基BDD电极,采用SEM观察BDD薄膜的表面形貌,用Raman检测BDD薄膜的成分,用电化学工作站测试BDD电极的电化学性能。选择活性橙X-GN染料废水作为降解对象,分别研究电流密度(20、50、100、150 m A/cm~2)、电解质浓度(0.025、0.05、0.1 mol/L)和溶液初始pH(3.78、6.74、10.92)等不同工艺参数对降解效率的影响,并采用紫外可见光分光光度计进行测试表征,使用能耗和总有机碳量表征降解效果。结果 BDD电极具有很好的电催化性能,其电势窗口为3.33 V,析氧电位达到2.45 V,远高于大多数有机物的氧化电位,电极表面反应受扩散步骤控制。结合活性橙X-GN染料溶液降解效果,得出100 mg/L活性橙X-GN溶液的最佳降解工艺参数为:电流密度100 m A/cm~2、电解质浓度0.05mol/L、溶液初始pH值3.78。采用最佳工艺参数处理5 h后,色度移除率达到99%,能耗为65.4 k W·h/m~3,TOC去除率达到56.95%。结论 BDD电极可以有效地降解活性橙X-GN染料废水。     

双氧水水热处理泡沫镍制备 Ni(OH) 2 自集流超级电容器电极材料

目的寻找一种简便、价廉、对环境友好的方法制备具有高比容、长寿命的Ni(OH)2自集流超级电容器电极材料。方法采用水热法(15%(质量分数)的H2O2溶液,180℃,24 h)直接在泡沫镍集流体上原位生长Ni(OH)2,并对其形貌、组成以及电化学性能进行研究。结果通过双氧水水热处理,可以在泡沫镍集流体上原位生长出边长400~600nm、厚度约200nm的Ni(OH)2六边形片,此为六方晶的β-Ni(OH)2。该电极材料在2mol/LKOH溶液中的最高比容为2534F/g(扫速1mV/s),且循环1000圈后,比容值仍保持在91%以上(扫速为50mV/s)。结论该制备方法简单价廉,对环境友好,制得的电极材料具有自支撑、自集流的特点,且具有优异的电化学性能和良好的循环稳定性。     

Preparation and characterization of polyvinylchloride membrane embedded with Cu nanoparticles for electrochemical oxidation in direct methanol fuel cell

Copper nanoparticles were prepared by the chemical reduction method. These copper particles were embedded into the polyvinylchloride (PVC) matrix as support and used as an electrode (PVC/Cu) for the oxidation of methanol fuel for improving the current response. The PVC/Cu electrodes were characterized by thermal gravimetric analysis (TGA) for thermal stability of the electrode, X-ray diffraction (XRD) for identification of copper nanoparticles in the electrode, Fourier transform infrared spectroscopy (FTIR) to identify the interaction between PVC and Cu and scan electron microscopy (SEM) with EDAX for the morphology of the electrode. The electrocatalytic activity of the electrode was characterized by the cyclic voltammetry, linear sweep voltammetry, and chronoamperometry techniques. An increase in the electrode activity was observed with the increase of copper quantity from 0.18 g (PVC/Cu-0.18 g) to 0.24 g (PVC/Cu-0.24 g) and the maximum was found at 0.24 g of copper in the electrode. Also, it was observed that the electrode achieved the maximum catalytic current in 0.5 mol/L CH₃OH + 1 mol/L NaOH solution. FTIR identified that water molecules, C—H group, copper nanoparticle and its oxide were available in the electrode. SEM images with EDAX showed that copper particles were properly embedded in the polyvinylchloride matrix.     

Cu0.3Mn0.7去合金化制备纳米多孔铜块体材料

采用去合金化法对Cu0.3Mn0.7合金进行自腐蚀制备出厚度为1 mm的纳米多孔铜块体材料。采用XRD、SEM、EDS、AAS等分析了样品的相组成、微观形貌和元素含量。结果表明：样品在室温0.1 mol/L盐酸溶液中自腐蚀10 d,得到成分单一,结构均匀的三维连通纳米多孔铜块体材料,其表面平均孔径尺寸约125 nm,平均骨架尺寸约80 nm,横截面平均孔径尺寸约300 nm。     

Al-Mg-Sn-Si-In铝合金在不同溶液中的腐蚀与电化学性能研究

研究了Al-0.5Mg-0.1Sn-0.1Si-0.02In合金作为铝空气电池的阳极材料,在2 mol/L NaCl,4 mol/L NaOH乙醇-10%水,4 mol/L NaOH溶液中的腐蚀行为及电化学性能。结果表明,该合金在4 mol/L NaOH乙醇-10%水溶液中性能优良,具有较高的阳极利用率及较低的自腐蚀速率。腐蚀形貌及电化学阻抗谱测试结果与合金腐蚀特性一致。通过对比Zn在4 mol/L NaOH溶液中的电化学性能,Al-0.5Mg-0.1Sn-0.1Si-0.02In合金在4 mol/L NaOH乙醇-10%水介质中作为铝空气电池的阳极材料具有可行性。     

Characteristics of graphite felt electrode electrochemically oxidized for vanadium redox battery application

The graphite felt was oxidized at a positive electrode potential in sulfuric acid solution.The electrochemical performance of the treated graphite felt served as electrode for vanadium redox battery was investigated with FT-IR,SEM,XPS,BET,cyclic voltammetry and testing VRB system,respectively.The results show that the molar ratio of O to C increases from 0.085 to 0.15 due to the increase of—COOH functional groups during electrochemical oxidation treatment,and the GF surface is eroded by electrochemical oxidation,resulting in the surface area increase from 0.33 m2/g to 0.49 m 2/g.The VRB with modified GF electrode exhibits excellent performance under a current density of 30 mA/cm 2 .The average current efficiency reaches 94%and average voltage efficiency reaches 85%.The improvement of electrochemical activity for the electrode is ascribed to the increase of the number of—COOH group and the special surface of GF.