Heterogeneous Electrocatalytic Reduction of Maleic Acid on Nanocrystalline TiO_2 Film Modified Ti Electrode

通过电化学合成前驱体和溶胶 -凝胶法在Ti表面修饰一层纳米TiO2 膜 ,SEM ,XRD测试表明晶型为锐钛矿型 ,晶粒平均尺寸为 2 5nm .采用循环伏安法、循环方波伏安法和电解合成法研究了纳米TiO2 膜电极在硫酸介质中的氧化还原行为以及对马来酸 (maleicacid)还原的电催化活性 .结果表明 ,纳米TiO2 膜电极在阴极扫描时有两对可逆氧化还原峰 ,可逆半波电位Er1/ 2 分别为 -0 .5 3V和 -0 .92V (vs .SCE ,扫描速度 0 .0 5V·s-1) ,对应于TiO2 /Ti2 O3 和TiO2 /Ti(OH) 3 两个氧化还原电对的可逆电极过程 .其中TiO2 /Ti2 O3 电对对马来酸具有异相电催化还原活性 ,纳米TiO2 膜中的TiⅣ/TiⅢ 氧化还原电对作为媒质间接电还原马来酸为丁二酸 (butanediacid) ,反应机理为电化学偶联随后化学催化反应 (EC′)机理 .The precursor Ti(OEt)_4 was prepared by anodic dissolution of metallic titanium in absolute ethanol and direct hydrolysis to prepare nanocrystalline TiO_2 film on titanium electrode (Ti/nano-TiO_2) by a sol-gel process. SEM and XRD were used to characterize the structure of nanocrystalline TiO_2 film (anatase, 25 nm). Redox behavior and electrocatalytic activities of the Ti/nano-TiO_2 electrode were investigated by cyclic voltammetry (CV) and cyclic osteryoung square wave voltammetry (COV) and bulk electrolysis. The results indicate that there are two pairs of well-defined redox peaks for Ti/nano-TiO_2 film electrode in 1 mol/L H_2SO_4 with E r_ 1/2 of -0.53 V and -0.92 V (vs. SCE) at 0.05 V·s -1 in correspondence with TiO_2/Ti_2O_3 and TiO_2/Ti(OH)_3 reversible electrode process and the heterogeneous electrocatalytic reduction activities of TiO_2/Ti_2O_3 redox in the electrode for maleic acid. It is found that the indirect electroreduction of maleic acid to butane diacid was achieved by Ti Ⅳ/Ti Ⅲ redox system on the nanocrystalline TiO_2 film surface, the electrode reaction mechanism is the called catalytic (EC′) mechanism.安徽省自然科学基金 (Nos.0 0 0 4 531 7,0 0 0 4 61 1 2 )资助项

Electrocatalytic Oxidation of Glucose on Carbon Nanotube/Nanocrystalline TiO_2 Film Loaded Pt Complex Electrode

用电化学循环伏安法和计时电位法研究了葡萄糖在碳纳米管 /纳米TiO2 膜载Pt (CNT/nano TiO2 /Pt)复合电极上的电催化氧化 .结果表明 ,在碱性介质中CNT/nano TiO2 /Pt复合电极对葡萄糖的电氧化具有高催化活性 ,葡萄糖氧化峰电流密度高达 13mA/cm2 ,比铂电极上的增大一倍 ;复合电极性能稳定 ,抗中毒能力强 ,不易发生氧化振荡 ,是葡萄糖燃料电池和葡萄糖传感器的高活性催化电极 .Electrocatalytic oxidation of glucose on carbon nanotube/nanocrystalline TiO 2 film loaded Pt (CNT/nano-TiO 2/Pt) complex electrode was investigated by cyclic voltammetry and chronopotentiometry. The results indicated that CNT/nano-TiO 2/Pt complex electrode has high catalytic activity to the electrochemical oxidation of glucose in alkaline media, and the peak current density of oxidation of glucose is up to 13 mA/cm 2, which is one time higher than that on a platinum electrode. The complex electrode performance is stable, and it is strong resistant to poisoning and difficult to oxidize oscillatory. It is a highly catalytic electrode for using in glucose fuel cell and glucose sensor.安徽省自然科学基金 (No.0 0 0 4 531 7);; 安徽省高校科研基金(Nos.2 0 0 3kj1 4 1 ,2 0 0 4kj1 64zd)资助项

Heterogeneous electrocatalytic reduction of maleic acid on nanocrystalline TiO2 film modified Ti electrode

The precursor Ti(OEt)(4) was prepared by anodic dissolution of metallic titanium in absolute ethanol and direct hydrolysis to prepare nanocrystalline TiO2 film on titanium electrode (Ti/nano-TiO2) by a sol-gel process. SEM and XRD were used to characterize the structure of nanocrystalline TiO2 film (anatase, 25 nm). Redox behavior and electrocatalytic activities of the Ti/nano-TiO2 electrode were investigated by cyclic voltammetry (CV) and cyclic osteryoung square wave voltammetry (COV) and bulk electrolysis. The results indicate that there are two pairs of well-defined redox peaks for Ti/nano-TiO2 film electrode in 1 mol/L H2SO4 with E-1/2(r) of -0.53 V and -0.92 V (vs. SCE) at 0.05 V (.) s(-1) in correspondence with TiO2/Ti2O3 and TiO2/Ti(OH)(3) reversible electrode process and the heterogeneous electrocatalytic reduction activities of TiO2/Ti2O3 redox in the electrode for maleic acid. It is found that the indirect electroreduction of maleic acid to butane diacid was achieved by Ti-IV/Ti-III redox system on the nanocrystalline TiO2 film surface, the electrode reaction mechanism is the called catalytic (EC') mechanism

Electrochemical synthesis of zinc complexes and preparation of nano-sized ZnO

Zinc complexes were directly prepared by using zinc metal as sacrificing anode in a cell without separating the cathode and anode spaces. The products were characterized by using FT-IR, NMR and Raman spectroscopy. The influence of temperature and conductive additives on product yield was also investigated. The study shows that direct electrochemical preparation of zinc complexes such as Zn(acac)(2), Zn(OEt)(2) (acac)(2) and Zn(OBu)(2)(acac)(2) has high current efficiency and electrolysis yield than that of Zn(OR)(2). Furthermore, these zinc complexes have high purity and can be directly used as sol-gel precursor for preparation of nanometer ZnO. Experimental results show that controlling temperature in the range of 50 similar to 60 degreesC, selecting R4NBr as conductive additives and preventing zinc anode from being covered by electrochemical products can improve product yield. The study also shows that nano-sized ZnO prepared by this method has monoclinic structure with a narrow size distribution of 5-10 nm

Electrocatalytic oxidation of glucose on carbon nanotube/nanocrystalline TiO2 film loaded Pt complex electrode

Electrocatalytic oxidation of glucose on carbon nanotube/nanocrystalline TiO2 film loaded Pt (CNT/nanoTiO(2)/Pt) complex electrode was investigated by cyclic voltammetry and chronopotentiometry. The results indicated that CNT/nano-TiO2/Pt complex electrode has high catalytic activity to the electrochemical oxidation of glucose in alkaline media, and the peak current density of oxidation of glucose is up to 13 mA/cm(2), which is one time higher than that on a platinum electrode. The complex electrode performance is stable, and it is strong resistant to poisoning and difficult to oxidize oscillatory. It is a highly catalytic electrode for using in glucose fuel cell and glucose sensor

Heterogeneous Electrocatalytic Reduction of p-Nitrobenzoic Acid on Nanocrystalline TiO_2 Film Modified Electrode

Redox behavior and electrocatalytic activities of the Ti/nano\|TiO\-2 electrode were investigated by cyclic voltammetry(CV) and bulk electrolysis. The results indicate that there are two pairs of well\|defined redox peaks for Ti/nano\|TiO\-2 film electrode in the 1 mol/L H\-2SO\-4 and 1 mol/L NaOH at 0.1 V/s corresponding to TiO\-2/ Ti\-2O\-3 and TiO\-2/Ti(OH)\-3 reversible electrode process. In 1 mol/L NaOH medium the peak potential evidently shift to the negative value with \%E\%\+r\-\{1/2\} being -1.38 and -1.72 V(\%vs\%.SCE), and the heterogeneous electrocatalytic reduction activities of TiO\-2/Ti\-2O\-3 redox for \%p\%\|nitrobenzoic acid (PNA) is very high. The indirect electroreduction of PNA to \%p\%\|aminobenzoic acid (PAA) by Ti\+Ⅳ/Ti\+Ⅲ redox system on nanocrystalline TiO\-2 film surface was found, and the electrode reaction mechanism is called electro\|catalytic(EC) mechanism. In the preparative electrolysis, the current efficiency was over 90%.安徽省自然科学基金 (批准号 :0 0 0 45 3 17);; 安徽省高校科研基金 (批准号 :2 0 0 3 kj13 1,2 0 0 4kj164 zd)资

电合成系列锌配合物及纳米ZnO的制备

采用锌金属为“牺牲”阳极 ,首次在无隔膜电解槽中 ,电化学一步法制备了纳米ZnO前驱体锌配合物Zn(OEt) 2 ,Zn(OBu) 2 ,Zn(acac) 2 ,Zn(OEt) 2 (acac) 2 ,Zn(OBu) 2 (acac) 2 (acac为乙酰丙酮基 ) ,产物通过红外光谱 (FT IR)、拉曼光谱和核磁共振进行表征 .同时采用含Zn(OEt) 2 (acac) 2 的电解液直接水解制备纳米ZnO粉体 ,纳米ZnO通过拉曼光谱、X射线粉末衍射 (XRD)和透射电子显微镜 (TEM)进行表征 .实验表明电解时防止阳极钝化 ,控制温度在 5 0～ 6 0℃之间 ,采用有机胺溴化物为导电盐 ,可以提高电合成效率 ;电解合成Zn(acac) 2 ,Zn(OEt) 2 (acac) 2 ,Zn(OBu) 2 (acac) 2 的电流效率比Zn(OEt) 2 ,Zn(OBu) 2 高 ,其中Zn(OEt) 2 (acac) 2 适宜作为溶胶 -凝胶法制备纳米ZnO的原料 ,制备得到的纳米ZnO经 6 0 0℃煅烧后呈球形单分散结构 ,平均粒径在 5～ 10nm左右

钛醇盐电化学合成的研究

采用钛金属为“牺牲”阳极,首次在无隔膜电解槽中,电化学一步法制备了纳米TiO_2前驱体钛醉盐Ti(OEt)_4,Ti(ORr-i)_4,Ti(OBu)_4.产物通过元素分析、红外光谱(FT-IR)、拉曼光谱进行表征.电化学一步法直接制备纳米材料前驱体钛醇盐,克服了传统化学方法合成金属醇盐步骤多、产率低、纯度达不到要求及后续分离繁琐等缺点.本文同时讨论了影响电合成钛醇盐的关键因素及可能的反应机理,实验表明钛在醇溶液中呈点蚀行为,钛醇盐卤化物Ti(Ⅲ)(OR)_nBr_m在阳极形成,然后被氧化为Ti(Ⅳ)(OR)_nBr_m,这种物质在阴极上ROH参与下被还原生成钛醇盐Ti(OR)_4,钛阳极表面拉曼光谱证实了上述观点.防止阳极钝化,温度控制在50～60℃之间,采用有机胺溴化物为导电盐,可以提高电合成收率

Heterogeneous Electrocatalytic Reduction of o-Nitrophenol on Nano-TiO_2 Film Modified Ti Electrode

通过电合成前驱体Ti(OEt)4直接水解法制备纳米TiO2膜修饰电极。用循环伏安法、电位阶跃法和电解合成法研究了纳米TiO2膜电极氧化还原行为以及电催化还原邻硝基苯酚(ONP)的活性与机理。结果表明,在硫酸介质中纳米TiO2膜电极在阴极扫描时具有2对可逆氧化还原峰,对应于TiO2/Ti2O3和TiO2/Ti(OH)3这2个氧化还原电对的可逆电极过程,可逆半波电位Er1/2分别为-056V和-096V(vs.SCE,扫描速度01V/s)。在酸性介质中纳米TiO2膜修饰电极对ONP的还原具有很高的异相电催化活性,TiO2/Ti2O3电对中的TiⅣ/TiⅢ氧化还原电对作为媒质间接电还原ONP为邻氨基苯酚(OAP),反应机理为电化学偶联随后化学催化反应(EC′)机理。在50℃使用纳米TiO2膜阴极间接电还原ONP为OAP的电流效率达90%以上,产物纯度为991%。The precursor Ti(OEt) 4 prepared by anodic dissolution of metallic titanium in absolute ethanol was directly hydrolyzed by a sol gel process to give nano TiO 2 film on a titanium electrode(Ti/nano TiO 2 ). Redox behavior and electrocatalytic activity of the Ti/nano TiO 2 electrode was investigated by cyclic voltammetry, potential step chronoampermetry, and bulk electrolysis. The results indicated that there were two pairs of well defined redox peaks for Ti/nano TiO 2 film electrode in the 1 mol/L H 2 SO 4 in correspondence with TiO 2 /Ti 2 O 3 and TiO 2 /Ti(OH) 3 reversible electrode processes with E r 1/2 being-0 56 V and-0 96 V( vs .SCE), respectively, at 0.1 V/s. Ti/nano TiO 2 electrode showed a high heterogeneous electrocatalytic activitiy in acidic medium in reduction of o nitrophenol. The indirect electroreduction of o nitrophenol to o aminophenol by Ti Ⅳ /Ti Ⅲ redox pair on nano TiO 2 film surface is believed to follow chemical catalysis mechanism(EC′). In preparative electrolysis at 50 ℃ on Ti/nano TiO 2 electrode the current efficiency for o aminophenol was over 90%.安徽省自然科学基金(00045317);; 安徽省高校科研基金(2003kj141,2004kj164zd)资助项

ELECTROCHEMICAL SYNTHESIS OF METAL ALKOXIDES USING SACRIFICING ANODE

采用金属为“牺牲”阳极 ,在无隔膜电解槽中 ,一步法制备金属醇盐 :Ti(OEt) 4、Ti(OPr -i) 4、Ti(OMe) 4(acac)、Cu(OEt) 2 、Cu(OBu) 2 、Ni(OEt) 2 和Mg(OEt) ,产物通过元素分析、红外光谱进行表征 .实验表明电极表面粗糙化处理 ,防止阳极纯化 ,温度控制在 5 0 - 60℃之间 ,采用有机溴化胺电导盐 ,可以提高电合成收率 .采用合金电极 ,可以有效克服不溶性金属醇盐在阳极的吸附问题 ,并同时合成几种金属醇盐 ,从而提高反应的电流效率 .Metal alkoxides were directly prepared using pure metal as sacrificing anode in absolute alcohol. Metal alkoxides were characterized by FTIR spectra and element analysis. The effects of temperature,conductive additives,trace water on product yield were also investigated. The results showed that the direct electrochemical preparation of metal alkoxides had high current efficiency and electrolysis yield. These metal alkoxides have high purity and can be directly used as precursor of nanometer oxides prepared by Sol-gel method. The experiments showed that controlling temperature under 50-60℃, selecting R 4NBr as conductive additives and preventing titanium anode from being passiviated can improve product yield. Using alloy as anode may be recommended as a technique for the synthesis of alkoxides, this process can run in sufficiently high current efficiency and high reaction activity.安徽省教育厅科研基金 ( 99JL0 0 75 ) ;; 安徽省自然科学基金 ( 0 0 0 46112