高活性硫化铅电极的制备及在量子点敏化太阳能电池中的应用

为了提高量子点敏化纳晶薄膜太阳能电池的光电转换效率,我们通过连续在酸和多硫溶液中处理铅片制备了对多硫电解液具有高电催化活性的硫化铅电极. 通过电化学阻抗谱测试评价所制备硫化铅电极的催化活性,从而确定制备高效硫化铅电极的最佳条件. 以在最佳条件下制备的硫化铅为对电极、CdSe量子点敏化TiO₂纳晶薄膜为工作电极和多硫电解液组装成量子点敏化太阳能电池. 光电性能测试结果表明所制备的电极具有良好的催化活性和光电转换性能. 与已报导的方法相比,新方法大幅度地减少制备过程所需的时间,但却提高了所制备的硫化铅对电极的催化活性. 通过X射线衍射和扫描电镜测试表征了硫化铅的生成过程,探讨了催化活性提高的原因.     

缺碳型介孔空心球状WC制备及其对甲醇氧化的电化学行为

采用喷雾干燥法制得空心球状结构偏钨酸铵, 通过固定床气固反应, 以CO/H₂为还原碳化气氛在700～900 ℃下制备了介孔结构空心球状碳化钨(WC). 经XRD, SEM及EDS测试表明, WC粉末样品在保持了单相WC的前提下, 样品存在一个微量缺碳的原子比例, 其W/C＞1, 且在高氢环境中WC球体表面有部分纳米颗粒依附于片状碳化钨基体上. 将制备得到的WC粉末样品制成微电极, 采用电化学测试技术研究了WC在硫酸介质中对甲醇的电催化氧化反应. 结果表明, 缺碳的介孔结构空心球状WC催化剂对甲醇氧化有着良好的电催化活性, 并对动力学参数进行了研究, 结果显示其反应的表观活化能为105.06 kJ/mol, 且其在微电极中的氧化行为受扩散控制.     

Effects of the preparation methods on the properties of Ni-La2O3-SiO2 catalysts for m -dinitrobenzene hydrogenation

Ni-La₂O₃-SiO₂ catalysts were prepared by wetness impregnation and sol-gel method followed by conventional drying and supercritical drying, respectively. Their physico-chemical properties and activity for the hydrogenation of m-dinitrobenzene to m-phenylenediamine were investigated by BET, XRD, TPR, H₂-TPD and activity tests. The results showed that the structural and catalytic properties of the Ni-La₂O₃-SiO₂ catalysts obviously depended on the preparation method and the drying mode. The catalyst prepared by the sol-gel method in combination with conventional drying exhibited the highest catalytic activity among the catalysts tested, attributable to its well-dispersed nickel particles and larger active nickel surface area.     

Enhanced Electrocatalytic Activity of Dual Template Based Pt/Cu‐zeolite A/Graphene for Methanol Electrooxidation

A novel Pt/Cu‐zeolite A/graphene based electrocatalyst was successfully prepared by chemical reduction method for methanol electrooxidation. Graphite oxide and Cu functionalized zeolite A were simultaneously reduced by NaBH₄ to prepare Cu‐zeolite A/graphene support which was used to deposit Pt nanoparticles. The nanostructure and composition of as‐prepared Pt/Cu‐zeolite A/graphene composites were characterized by X‐ray diffractometer, X‐ray fluorescence, Fourier transform infrared spectrometer and scanning electron microscopy. The electrocatalytic properties of Pt/Cu‐zeolite A/graphene modified electrode for methanol oxidation were investigated by cyclic voltammetry and chronoamperometry in 0.10 mol/L H₂SO₄ + 0.50 mol/L CH₃OH solution. Compared with Pt/zeolite A/graphene electrode and Pt/graphene electrode, Pt/Cu‐zeolite A/graphene based electrode exhibited obviously enhanced current and higher electrocatalytic activity for methanol electrooxidation. The increased electrocatalytic activity was attributed to the presence of zeolite A and reduced graphene oxide based dual template, which significantly increased the effective electrode surface and facilitated the diffusion of analytes into the electroactive catalyst.     

A novel non-enzyme hydrogen peroxide sensor based on an electrode modified with carbon nanotube-wired CuO nanoflowers

We have prepared a novel sensor for hydrogen peroxide that is based on a glassy carbon electrode modified with a film containing multi-walled carbon nanotubes wired to CuO nanoflowers. The nanoflowers were characterized by X-ray powder diffraction, and the electrode was characterized by cyclic voltammetry (CV) and scanning electron microscopy. The response of the modified electrode towards hydrogen peroxide was investigated by CV and chronoamperometry and showed it to exhibit high electrocatalytic activity, with a linear range from 0.5?μM to 82?μM and a detection limit of 0.16?μM. The sensor also displays excellent selectivity and stability.

Synthesis of molecular imprinted polymer modified TiO2 nanotube array electrode and their photoelectrocatalytic activity

A tetracycline hydrochloride (TC) molecularly imprinted polymer (MIP) modified TiO₂ nanotube array electrode was prepared via surface molecular imprinting. Its surface was structured with surface voids and the nanotubes were open at top end with an average diameter of approximately 50 nm. The MIP-modified TiO₂ nanotube array with anatase phase was identified by XRD and a distinguishable red shift in the absorption spectrum was observed. The MIP-modified electrode also exhibited a high adsorption capacity for TC due to its high surface area providing imprinted sites. Photocurrent was generated on the MIP-modified photoanode using the simulated solar spectrum and increased with the increase of positive bias potential. Under simulated solar light irradiation, the MIP-modified TiO₂ nanotube array electrode exhibited enhanced photoelectrocatalytic (PEC) activity with the apparent first-order rate constant being 1.2-fold of that with TiO₂ nanotube array electrode. The effect of the thickness of the MIP layer on the PEC activity was also evaluated.     

金复合介孔SBA-15吸附血红蛋白在H2O2电催化反应中的应用

以P123嵌段共聚物表面活性剂为模板剂制备介孔氧化硅SBA-15,并用沉积-沉淀(DP)法在SBA-15介孔表面负载纳米Au颗粒制备得到金复合介孔SBA-15材料(Au-SBA-15).再以Au-SBA-15材料制备玻碳修饰电极,将血红蛋白固定于修饰电极上用循环伏安法考察其对不同浓度H2O2溶液的电催化反应.在固定了血红蛋白的Hb/Au-SBA-15/GC修饰电极上,H2O2在+0.95 V处出现了氧化峰,且随着H2O2浓度的增大峰电流不断增加,说明金复合介孔氧化硅材料具有良好的生物兼容性,有利于血红蛋白的固定,其修饰电极对H2O2溶液具有一定的电催化作用.     

Silver Nanograins Incorporated PEDOT Modified Electrode for Electrocatalytic Sensing of Hydrogen Peroxide

A silver nanograins (Ag_NGs) incorporated poly[3,4‐ethylenedioxythiophene] (PEDOT) modified electrode was prepared by a simple electrochemical method without using any stabilizer or reducing agent. The surface morphology and thickness of the resulting modified electrode was characterized by using AFM. It was found that the size of the silver particles in the PEDOT modified electrode was smaller than that in the bare electrode. AFM studies also revealed that Ag_NGs were uniformly distributed in the PEDOT modified electrode and the thickness of the film was found to be 35 nm. The Ag_NGs incorporated PEDOT modified electrode exhibited good electrocatalytic activity towards the reduction of hydrogen peroxide without an enzyme or mediator immobilized in the electrode. It has shown good amperometric response to hydrogen peroxide (H₂O₂) with a detection limit of 7 μM and a response time of 5 s.     

Preparation of Sb2O3‐loaded Activated Carbon Particle Electrode and Its Electrocatalytic Degradation of Methyl Orange in a Three‐dimensional Electrode Cell

Electrocatalysis on the degradation of methyl orange is investigated using Sb₂O₃‐loaded activated carbon (Sb₂O₃/AC), a new particle electrode. The electrode was prepared by an impregnation method. An orthogonal array with four factors and three levels was selected to carry out the experiment. Electrocatalysis on the degradation of methyl orange through Sb₂O₃/AC was characterized by a series of parameters, including the amount of the particle electrode, the concentration of Na₂SO₄, the cell voltage, and the electrolysis time, and the results were compared with those of a conventional AC particle electrode. The results indicate that calcination temperature has the greatest impact on the catalytic activity of the particle electrode. The optimal conditions for preparing the Sb₂O₃/AC electrode include an 8 mL SbCl₃ solution, 90 min hydrolysis time, 400 °C calcination temperature, and 180 min calcination time. As well, the degradation efficiency of the Sb₂O₃/AC electrode is consistently higher than that of the AC electrode under the same electrolysis conditions. The electrochemical oxidation of methyl orange of both electrodes conformed to pseudo first‐order kinetics, but the rate constant of the Sb₂O₃/AC electrode was 2.29 times that of the AC electrode; this is likely due to the high electrocatalytic activity of the experimental electrode. The electrocatalysis results exhibited the synergetic effects of AC and Sb₂O₃ in the new particle electrode.     

Preparation of a p-n heterojunction 2D BiOI nanosheet/1DBiPO4 nanorod composite electrode for enhanced visible light photoelectrocatalysis

In this study, a 2D BiOI nanosheet/1D BiPO₄ nanorod/fluorine-doped tin oxide (FTO) composite electrode with a p-n heterojunction structure was prepared by a two-step electrodeposition method. Field-emission scanning electron microscopy, transmission electron microscopy, X-ray photoelectron spectroscopy, UV-visible diffuse reflectance spectroscopy, and electrochemical testing were used to characterize its composition, crystal morphology, and optical properties. The BiOI/BiPO₄/FTO composite electrode has higher photoelectrocatalytic (PEC) activity for the degradation of tetracycline than pure BiPO₄ and BiOI. The PEC activity of the composite was 1.98 times and 2.46 times higher than those of the BiOI/FTO and BiPO₄/FTO electrodes, respectively. The effects of the working voltage and BiOI deposition time on the degradation of tetracycline were investigated. The optimum BiOI deposition time was found to be 150 s and the optimum working voltage is 1.2 V. Trapping experiments showed that hydroxyl radicals (?OH) and superoxide radicals (?O₂^?) are the major reactive species in the PEC degradation process. The BiOI/BiPO₄/FTO composite electrode has good stability, and the tetracycline removal efficiency remains substantially unchanged after four cycles in a static system. The reason for the PEC efficiency enhancement in the BiOI/BiPO₄/FTO composite electrode is the increased visible light absorption range and the p-n heterojunction structure, which promotes the separation and migration of the photogenerated electrons and holes.     

Self-assembly preparation of mesoporous hollow nanospheric manganese dioxide and its application in zinc-air battery

In this work, mesoporous manganese dioxide with novel hollow nanospheric structure was prepared by a facile, template-free self-assembly process at room temperature in a short period of time. The product was characterized by X-ray diffraction, scanning electron microscopy, and energy-dispersive X-ray spectroscopy. The results indicate that the as-prepared material has a special mesoporous hollow nanospheric morphology and a typical composition of γ-MnO₂. Polarization curve, chronoamperometry and Tafel plot tests demonstrate that this nanostructured material has high electrocatalytic activity for the reduction of dioxygen compared to commercial electrolytic MnO₂ (EMD). Electrochemical impedance spectroscopy that was analyzed by equivalent circuit shows that as-prepared MnO₂-catalysted air electrode has a small contact resistance and ohmic resistance, a low value of electrochemical polarization resistance. An all solid-state zinc-air cell has been fabricated with this material as electrocatalyst for oxygen electrode and potassium salt of cross-linked poly(acrylic acid) as an alkaline polymer gel electrolyte. The cell has a better discharge characteristic than that of the cell employing EMD at room temperature.     

Enhanced Photoelectrochemical Property of Zn Loaded TiO2 Nanotube Arrays Electrode

TiO₂ nanotube arrays (TNTs) electrode loaded with Zn nanoparticles was prepared by anodization and the size of Zn nanoparticle loaded on TNTs electrode was controlled bychronoamperometry deposition time. Results of SEM and XRD analysis show that Zn nanoparticles had a diameter of about 15-25 nm when the deposition time was 3-5 s. The UV-Vis diffuse reflectance spectra show the Zn loaded harvest light with 480-780 nm more effectively than the unloaded sample. The photocurrent response of Zn loaded TNTs electrodes were studied, the results showed that TNTs electrodes loaded with Zn nanoparti-cles has 50% increased photocurrent response under high-pressure mercury lamp irradiation compared with unloaded TNTs electrode.     

Reactivity of the Pt/WO3/GC Electrode Towards Ethylene Glycol Oxidation in 0.1 M H2SO4

WO₃ has been prepared via thermal decomposition of ammonium paratungstate. The obtained oxide has been characterized by X‐ray diffraction (XRD) spectroscopy. The particle size was found to increase with increasing calcination temperature. The modified Pt/WO₃/GC electrode has been prepared and characterized using various analytical and electrochemical techniques. The electrochemical oxidation of ethylene glycol (EG) on the modified electrode was investigated and compared with that of a Pt/GC electrode in acidic solution. The presence of WO₃ enhanced the electrode activity towards EG oxidation. The enhancement factor was found to depend on the ratio of WO₃:Pt as well as on the calcination temperature during WO₃ preparation     

Electrocatalytic Reduction of Oxygen at Multi‐Walled Carbon Nanotubes and Cobalt Porphyrin Modified Glassy Carbon Electrode

The multi‐walled carbon nanotubes (MWNTs) modified glassy carbon electrode exhibited electrocatalytic activity to the reduction of oxygen in 0.1 M HAc‐NaAc (pH 3.8) buffer solution. Further modification with cobalt porphyrin film on the MWNTs by adsorption, the resulted modified electrode showed more efficient catalytic activity to O₂ reduction. The reduction peak potential of O₂ is shifted much more positively to 0.12 V (vs. Ag/AgCl), and the peak current is increased greatly. Cyclic voltammetry (CV), transmission electron microscopy (TEM), X‐ray photoelectron spectroscopy (XPS) and atomic force microscopy (AFM), were used to characterize the material and the modified film on electrode surface. Electrochemical experiments gave the total number of electron transfer for oxygen reduction as about 3, which indicated a co‐exist process of 2 electrons and 4 electrons for reduction of oxygen at this modified electrode. Meanwhile, the catalytic activities of the multilayer film (MWNTs/CoTMPyP)_n prepared by layer‐by‐layer method were investigated, and the results showed that the peak current of O₂ reduction increased and the peak potential shifted to a positive direction with the increase of layer numbers.     

Thiol oxidation at 2-mercaptopyrimidine-appended cobalt phthalocyanine modified glassy carbon electrodes

The electrocatalytic activity of cobalt tetra-2-mercaptopyrimidylphthalocyanine-modified glassy carbon electrode (CoTMPyrPc-GCE) toward gluthathione, l-cysteine and 2-mercaptoethanol has been investigated. CoTMPyrPc-GCE provides a significant improvement on the reported oxidation potential of l-cysteine in pH 4.0 phosphate buffered solution. The oxidation peak potential (E_p), for l-cysteine, was 0.15 V – a relatively lowered oxidation potential compared to reported phthalocyanine complexes. The electrode prepared by drop-dry/thermal annealing method was very stable and sensitive over a long period of time. The stability has been attributed to the thermal annealing and the structure of the mercaptopyrimidine on the periphery of the CoPc.     

High performance gold-supported platinum electrocatalyst for oxygen reduction

High performance gold-supported Pt electrocatalyst for the reduction of oxygen was prepared by replacing Cu adlayers, deposited potentiostatically on Au, with Pt at open-circuit potential in a 0.1 M HCl solution containing K₂PtCl₆. Auger Electron Spectroscopy and Atomic Force Microscopy reveal the surface modification. The kinetics of oxygen reduction on this platinum modified electrode was studied by the rotating-disc electrode technique. The activity of the electrode is lower than the activity of a smooth Pt electrode in the negative potential scan, but it is significantly higher in the positive scan.     

Influence of highly efficient PbS counter electrode on photovoltaic performance of CdSe quantum dots-sensitized solar cells

PbS electrode with high catalytic activity to S_n ^2? reduction certificated by the measurements of electrochemical impedance spectroscopy and cyclic voltammetry was prepared by a simple method. The high catalytic activity makes it be a low-cost alternative counter electrode to platinum (Pt) to be used in quantum dots-sensitized solar cells (QDSSCs) based on polysulfide electrolyte. The photovoltaic performance enhancement of the quantum dots (QDs)-sensitized semiconductor thin films due to the PbS counter electrode was evaluated by fabricating QDSSCs based on CdSe QDs-sensitized ZnO (SnO₂) thin film. CdSe QDs-sensitized ZnO thin film has the lower internal total series resistance and electron transmission time, the higher electron lifetime and electron collection efficiency than the CdSe QDs-sensitized SnO₂ thin film. Replacing the Pt counter electrode with the PbS counter electrode leads to more improvement on the short circuit photocurrent density for QDSSC based on the ZnO thin film than the SnO₂ thin film. Therefore, the process to limit the photovoltaic performance of CdSe QDs-sensitized solar cell and the possible way to improve the photovoltaic performance were analyzed.     

A novel nitrite sensor fabricated through anchoring nickel-tetrahydroxy-phthalocyanine and polyethylene oxide film onto glassy carbon electrode by a two-step covalent modification approach

In this paper, we present a two-step covalent modification approach to fabricate a novel nitrite sensor through anchoring nickel-tetrahydroxy-phthalocyanine (NiPc(OH)₄) and polyethylene oxide (PEO) onto a glassy carbon electrode (GCE). The surface morphology of the prepared NiPc(OH)₄/PEO composite films under different dry conditions was characterized by scanning electron microscopy (SEM). The electrochemical behavior of NiPc(OH)₄/PEO composite film modified GCE toward the catalytic oxidation of nitrite in pH 7.0 phosphate buffer solution (PBS) was investigated by cyclic voltammetry (CV). After drying under an infrared lamp, the fabricated sensor showed a pronounced electrocatalytic activity improvement toward the oxidation of nitrite and led to a significant decrease in the anodic overpotentials compared with bare GCE, which should be ascribed to the synergistic effect of NiPc(OH)₄ and PEO, as well as the enlarged electrochemical effective surface area after drying. Using differential pulse voltammetry (DPV), the sensor gave a linear response to nitrite over the concentration range of 0.1–5,300 μM, with a detection limit of 0.0522 μM. The nitrite sensor exhibits good sensitivity, selectivity, and stability and has been applied for the determination of nitrite in water samples.     

电解煤浆制氢钛基阳极铂铁合金催化剂的制备及电催化活性研究

将预处理后的钛片作为电极基体, 采用恒电流法沉积Pt和Fe, 通过高温热处理得到Ti/Pt-Fe电极, 通过扫描电镜(SEM)、X射线衍射(XRD)、电子能谱(EDS)以及等离子发射光谱(ICP)等方法对所制备电极表面形貌、组分的合金化程度、催化层成分组成以及电极寿命等进行了表征; 在煤浆电解过程中, 采用两电极体系, 对所制备电极的电催化活性进行了测试. 结果表明: 所制备的电极表面呈层状结构, 且有大量峰形突起, 催化层形成了PtFe合金, 合金化程度较高, 与同面积的铂片电极、Ti/TiO₂Pt-Ru电极相比, 大大提高了电催化活性, 降低了电极成本.