电场对TiO2纳米膜光催化性能的影响

 以泡沫镍为基材,采用溶胶-凝胶法制备了TiO2纳米膜光催化剂. 在自制外加电场光催化反应装置中,对催化剂施加一定的偏电压,研究了甲基橙溶液的光电催化降解反应,考察了偏压极性、阳极偏压和甲基橙初始溶液浓度等对降解效率的影响,并比较了光电催化与光催化、光解对甲基橙溶液降解的差异. 结果表明,外加阳极偏压形成的电场可以较大幅度提高甲基橙溶液的降解效率. 从半导体和量子力学理论出发探讨了电场促进光催化反应的作用机理.     

光电催化降解邻苯二甲酸二乙酯的研究

采用sol-gel法制备TiO2薄膜光电极，以该电极为工作电极，铂丝作对电极，饱和甘汞电极为参比电极，对邻苯二甲酸乙酯的光电催化降解进行了研究。结果表明：该电极具有n型半导体的特征行为，在外加偏压为＋0．7v、pH=2、50mg／L的H2O2中对初始浓度为50mg／L的DEP溶液光照180min降解率达67．85％，讨论了氧的存在、外加偏压等因素对光电催化反应的影响。     

钛基TiO2纳米管阵列电极的光电催化性能

应用电化学阳极氧化法在纯Ti基底上制备高度有序的TiO2纳米管阵列,考察了Ti/TiO2光阳极的光电化学响应.以苯酚溶液为目标污染物,研究Ti/TiO2电极的光电催化性能,并与光催化性能进行比较.结果表明,该电极光电催化性能优于光催化性能.施加0.6 V电压时,光电催化性能最好.电化学阻抗谱分析显示,光电催化和光催化降解过程的速控步骤均为表面反应步骤,外加偏压减小了界面电荷转移阻抗,提高了光生载流子的分离效率.     

苯胺在SnO_2/Ti电极上的电化学氧化

研究了以SnO_2/Ti为阳极降解苯胺的电化学降解特性.实验结果表明,同Pt电极比较,掺F的SnO_2/Ti电极对苯胺的降解表现了明显的效果.苯胺在SnO_2/Ti电极上氧化降解速率主要决定于其中间产物的阳极溶解行为.由中间产物构成的有机膜的阳极溶解是反应的慢步骤.研究了苯胺溶液的浓度、pH和电流密度对苯胺降解速率的影响规律,对反应中间产物的复杂性及构成“膜”的理化性质进行了初步分析.     

苯胺在SnO2/Ti电极上的电化学氧化

研究了以SnO2/Ti为阳极降解苯胺的电化学降解特性.实验结果表明,同Pt电极比较,掺 F的SnO2/Ti电极对苯胺的降解表现了明显的效果.苯胺在SnO2/Ti电极上氧化降解速率主要决 定于其中间产物的阳极溶解行为.由中间产物构成的有机膜的阳极溶解是反应的慢步骤.研究 了苯胺溶液的浓度、pH和电流密度对苯胺降解速率的影响规律,对反应中间产物的复杂性及 构成“膜”的理化性质进行了初步分析.     

CdSe/泡沫镍薄膜电极对结晶紫的光电催化降解

采用恒电位电沉积法,以泡沫镍为基底电极,制备了CdSe/泡沫镍薄膜电极,采用扫描电子显微镜、紫外可见漫反射光谱和能谱分析表征了CdSe薄膜的形貌及其组成。应用该电极研究结晶紫溶液在光电催化降解过程中的COD去除率。结果表明,以白炽灯(100 W,2只)为光源,采用电沉积30 min所得的CdSe/泡沫镍薄膜电极为工作电极,外加偏压为0.4 V(vs.SCE),0.01 mol/L NaCl为电解质,光电催化降解浓度为0.001 g/L的结晶紫溶液120 min,COD去除率达到84.3%。     

光/电/化学催化降解水中酸性大红3R染料的研究

以高纯石墨电极、TiO₂/Ti薄膜电极和甘汞电极, 分别为阴极、阳极和参比电极, 设计研制出了新型光-电-化学催化集成反应器. 在紫外光和外加电场的作用下, 不仅TiO₂/Ti薄膜电极能对阳极槽中的酸性大红3R进行光电催化降解脱色, 且在阴极上产生的过氧化氢及其与亚铁离子形成的H2O₂/Fe²⁺催化体系, 对阴极槽中的染料溶液也有良好的脱色降解作用. 该催化集成反应器充分利用了光生空穴和光生电子, 实现了在阳、阴两极同时对染料进行降解脱色处理, 达到了“双极双效”的目的. 实验表明, 当用0.02 mol·L^−1硫酸钠为支持电解质、初始pH = 3和阴极电位−E_c = 0.66V的条件下, 阴极槽和阳极槽对30 mg·L^−1酸性大红3R溶液的脱色降解率分别达到92%和60%, 与双极单效的光电催化相比, 效率显著提高.     

TiO2纳米管阵列光电催化氧化处理氨氮废水

用电化学阳极氧化法制备了高度有序的钛基二氧化钛纳米管阵列薄膜。用场发射扫描电镜(FE-SEM)、X射线衍射(XRD)表征样品的形貌与晶型特征。以二氧化钛纳米管阵列为光阳极,石墨为对电极,测试了不同pH值和外加偏压条件下的光电流响应和光电催化氧化降解NH4Cl水溶液(以N计,100 mg·L-1)的效率。结果表明:所制备的TiO2纳米管阵列具有锐钛矿和金红石的混晶结构,且主要晶型为锐钛矿。光电流响应的强弱与光电催化氧化效率的高低相对应,降解氨氮废水的最佳条件为pH=11,偏压为1.0 V。     

TiO2薄膜光电极能带结构和催化活性的初探

以阳极氧化法制得的TiO2薄膜光电极为工作电极,铂环为对电极,饱和甘汞电极为参比电极,组成光电催化降解苯酚体系.运用电化学阻抗图谱(EIS),测得光电催化过程中TiO2薄膜光电极的空间电荷层电容,计算出半导体能带结构参数———空间电荷层宽度W.结果证明:当空间电荷层宽度W随阳极偏压增加而增大时,TiO2薄膜电极光催化活性提高;当其等于薄膜厚度时,光催化活性最好,此时出现最佳偏压值;继续增加偏压,活性反而有所下降.     

用钌钛氧化膜电极电解食盐水时pH对放氧速率的影响及其机理的探讨

用气体吸收法测定了电解食盐水时阳极气体中氯与氧的含量,得到含氧率随阳极液pH值(pH~s)变化的规律.讨论了电解过程中H~ 和HClO的扩散行为及其对放氧速率的影响,得到放氧速率、电极表面附近pH值(pH~e)对pH~s的依赖关系,与实验结果相符.     

Electrochemical Monitoring of Photoelectrocatalytic Degradation of 3,4‐Dichlorophenol Using TiO2 Thin Film Modified Graphite Electrode

A novel electrode was prepared by forming TiO₂ thin films using a commercially available TiO₂ powder (Degussa P25) on graphite plates for water photoelectrocatalytic decontamination. In addition to, for the first time the photoelectrochemical degradation of 3,4‐dichlorophenol was investigated. The effects of applied potential, pH, and initial 3,4‐dichlorophenol concentration on the photoelectrocatalytic (PEC) degradation of 3,4‐dichlorophenol using ultraviolet (UV) illuminated TiO₂/graphite (TiO₂/C) thin film electrode was examined and discussed. Also, direct photolysis (DP), electrochemical oxidation (EC), photocatalytic (PC) and photoelectrocatalytic (PEC) degradation of 3,4‐dichlorophenol were compared. Results show that the best responses for PEC are obtained at applied potential 1.2 V versus reference electrode, pH 8.0 and initial 3,4‐dichlorophenol concentration 6.7 mg L^?1.     

Properties and Photoelectrocatalytic Behaviour of Sol-Gel Derived TiO2 Thin Films

Titanium dioxide (TiO₂) thin films have been prepared on indium doped tin oxide (ITO) glass by sol-gel dip-coating method. Properties of the films were determined as a function of heat-treatment by X-ray diffraction, scanning electron microscopy and photoelectrochemical tests. The films heat-treated at higher temperatures show better crystallinity and photoresponse. The microscopic structure on the film after heat-treatment is attributed to the incorporation of organic polymer into the precursor solution. The performance of the electrodes treated at different temperature on photoelectrocatalytic degradation of methyl orange was investigated. The effect of applied potential and the ability of the electrode to be repeatedly used in photoelectrocatalytic degradation were also evaluated.     

Visible light photoelectrocatalytic degradation of rhodamine B using a dye-sensitised TiO2 electrode

Titanium dioxide is a promising catalyst for application in the photodegradation of organic pollutants in water due to its powerful oxidising property and long-term photostability. This study presents the production of titanium dioxide using the sol-gel process, dye sensitisation of the TiO₂ electrode, and the performance of that cell. Sensitisation of titanium dioxide was performed using a dye, i.e., Fe(II)-polypyridyl complexes. The photoelectrocatalytic degradation of rhodamine B (RB) using ITO/TiO₂/dye as electrode was investigated via a series of potentials, from +1.0 V to ?1.0 V, and at various pH and NaCl concentration values (ITO is indium tin oxide conductive glass). The photoelectrocatalytic degradation of RB was performed with a visible light lamp. The change in the absorbance of RB with various potentials indicated that the absorbance of RB in solution systems with the sensitised TiO₂ electrodes decreased with increasing anodic potential bias. The degradation cell exhibited better performance when the positive anodic bias was applied. The pH values of RB in solution systems also influence the photoelectrodegradation process because of the different RB species present. NaCl concentration also affects the activity of RB photoelectrocatalytic degradation due to changes in the ionic strength character of the electrolyte.     

Efficient photoelectrocatalytic activity of TiO2/Ti anode fabricated by metalorganic chemical vapor deposition (MOCVD)

Nanosized TiO₂/Ti photoanodes fabricated by metalorganic chemical vapor deposition (MOCVD) under different deposition temperatures were characterized and applied to the photoelectrocatalytic degradation of model pollutant of phenol. The anode prepared at 773 K was verified in anatase phase with a size about 60 nm and achieved the best photoelectrocatalytic activity, where IPCE could reach as high as 89% and the photoconversion efficiency peaked at 8.4%. The photoelectrocatalytic degradation of phenol was found well fit a pseudo-first-order kinetics, and kept stable performance in five continuous runs, confirming potential application of the electrode prepared by MOCVD for organic pollutants abatement.     

Photoelectrocatalytic degradation of 3-nitrophenol at surface of Ti/TiO2 electrode

The widely utilization of phenol and its derivatives such as 3-nitrophenol (3-NP) has led to the worldwide pollution in the environment. In this study, Ti/TiO₂ photoelectrode was prepared with anodic oxidation of Ti foil electrode and then the photoelectrocatalytic (PEC) degradation of 3-NP was performed via this electrode, comparing with photocatalytic (PC), electrooxidation and direct photolysis by ultraviolet light. A significant photoelectrochemical synergetic effect in 3-NP degradation was observed on the Ti/TiO₂ electrode and rate constant for the PEC process of Ti/TiO₂ electrode was about three times as high as its PC degradation process. 3-NP concentration monitoring was carried out with differential pulse voltammetry. Results showed that PEC degradation has highest effect on concentration decreasing of 3-NP at solution and degraded it about 38 %, while other processes degradation efficiencies were about 4, 7, and 12 % for electrooxidation, direct photolysis and photocatalytic degradation, respectively. Finally, effects of solution pH and applied potential on degradation efficiency were studied and results showed that optimum pH for degradation is equal 4.00 and optimum potential is 1.2 V vs. Ag|AgCl|KCl (3M) reference electrode.     

氢还原二氧化钛光催化降解磺基水杨酸的研究

研究了由偏钛酸在不同温度下焙烧制成的TiO2,经氢还原后用于光催化降解磺基水杨酸（SSal) 以及TiO2的漫反射光谱和荧光光谱特征。结果表明,锐钛型TiO2在经550℃ 氢还原处理120min后,光催化活性明显提高;600℃条件下焙烧制得的TiO2,经氢还原后其光催化降解SS al的反应活性最高。漫反射光谱结果表明,800℃条件下焙烧制得的TiO2,开始出现转晶现象,从锐钛型逐渐向金红石型过渡。TiO2荧光光谱的峰面积（F）和倍频峰面积（R）的比值越大。TiO2光催化降解SSal的活性越高,提出了氢还原后TiO2的光催化作用机制。     

TiO2膜电极光电催化降解苯甲酸的机理研究

利用自制纳米TiO2薄膜作电极, 对苯甲酸光电催化降解过程进行了系统研究. 同时利用扫描电镜(SEM)、X射线衍射图谱(XRD)和光电流-电压响应谱分析光催化剂的微观性质和光电性能. 选取较高的pH 10.5, 以利于苯甲酸降解中间产物的检测(GC/MS). 通过对比光电催化与单一的TiO2光催化体系中苯甲酸的降解动力学、总有机碳(TOC)的去除率、降解产物的生成(GC/MS)及活性自由基物种的产生(ESR), 提出光电催化降解苯甲酸的具体反应路径和氧化机理. 羟基化的苯甲酸在羟基自由基与活性氧自由基的共同作用下, 经由含六个碳原子的二酸(顺式己二烯二酸), 被进一步氧化成小分子酸和CO2.