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31.
An investigation has been carried out to attempt to understand the unusually low apparent symmetry factor observed during the reduction of V(5) at higher overpotentials at carbon electrodes (typically <0.13, or >460 mV decade−1). This reaction is of interest because it occurs in vanadium redox-flow batteries (VRBs) during discharge. Polarisation curves were measured using a rotating disk electrode (RDE). The reaction was not solution mass transport controlled, was pH independent (ca from 0 to 1), and the observed Tafel slope was unaffected by V(5) concentration over a range from 0.031 to 280 mM. Electrode double layer capacitance measurements were also carried out in sulphuric acid with and without vanadium. These tests showed that the presence of V(5) caused a suppression of the normal carbon surface quinone pseudocapacitance, as well as the appearance of two new pseudocapacitance peaks, one around 0.175-0.2 V and the other around 0.675-0.725 V versus SCE. The observed results do not appear consistent with a precipitated film causing diffusion limitations or causing IR drop. A model is developed to try to explain the data, which involves electron transfer through an adsorbed layer of vanadium. 相似文献
32.
Results are reported of experiments and modelling of cathodic Pb and anodic PbO2 electrodeposition, aimed at developing a process using both reactions simultaneously for treating aqueous effluents from lead–acid battery recycling plants. Pb(II) solubilities and equilibrium potentials were calculated as functions of pH and sulfate activities. Using kinetic parameters from the literature or determined experimentally, models were developed for current density–potential and current efficiency–potential relationships, together with the current density dependence of specific electrical energy consumptions for Pb(II) recovery. Experimental current density–potential and charge efficiency–potential relationships were in broad agreement with model predictions, with near unity current efficiencies for mass transport controlled PbO2 deposition from electrolytes containing 1 mol Pb(II) m–3 at pH 12. However, charge efficiencies for cathodic deposition of lead were typically 0.2 for 1 mol Pb(II) m–3 + 1 mol O2 (aq) m–3; removal of dissolved oxygen was predicted and determined to increase current efficiencies to near unity. Pb(II) concentrations were depleted to <60 ppb in a batch recycle reactor system with graphite felt anodes and graphite or titanium felt cathodes. Simultaneous cathodic Pb and anodic PbO2 electrodeposition resulted in more rapid Pb(II) depletion than for either reaction separately. 相似文献
33.
《青岛科技大学学报(自然科学版)》2010,(5)
以偶氮氯膦Ⅲ(CPAⅢ)作为显色剂,研究可见光分光光度计测定含偕胺肟基功能高分子膜螯合电极对铀酰离子的吸附量的实验方法。确定了分光光度法测定的铀酰离子吸附量的实验条件:吸收光波长670 nm,CPAⅢ标准溶液(0.001 mol.L-1)的用量3mL,测定体系的最佳pH值1.0,室温下显色时间2 min。在此实验条件下,绘制了铀的工作曲线,并得到摩尔吸光系数为ε=29 750 mol-1.L.cm-1。对比电子能谱法所测定的脱附铀前后的螯合电极表面的铀含量(脱附前后亮区铀含量分别为38.12%和6.29%,暗区铀含量都为零),得到分光光度计法测定的铀含量并不是螯合电板表面的真实铀含量,但却是脱附下来的铀的真实量,这肯定了分光光度法测定铀的吸附量优势所在。 相似文献
34.
Marta Pérez-Morales 《Electrochimica acta》2006,51(18):3714-3718
In this work, the mediator and/or catalytic properties of modified ITO electrodes by oxidative electrodeposition of Ni-porphyrins have been analyzed. Thus, monolayers containing viologen or azobenzene derivatives, have been transferred onto the porphyrin modified electrodes by using the Langmuir-Blodgett (LB) technique. Following, the redox processes of these compounds forming the LB films and deposited on the modified electrode and the bare ITO have been investigated.The obtained results reveal not only the excellent mediator character of the porphyrinic electrodeposit throughout the viologen redox processes, but also its the catalytic action over the azobenzene kinetics. Specifically, for the last case, the NiTMPyP films accelerate the azobenzene kinetics up to 100 times with respect to those results obtained in absence of porphyrin. 相似文献
35.
Joon-Hyung Jin 《Electrochimica acta》2007,52(11):3863-3869
Protoporphyrin IX (PPIX) was immobilized on Au surfaces for the electrochemical oxidation of dopamine (DA) and epinephrine (EP). Two procedures for the immobilization were employed. One class of modified electrodes was prepared by immobilizing the PPIX into polypyrrole (PPy) films synthesized by anodic electropolymerization. The other procedure involved the immobilization of PPIX on an electrode modified by a 11-mercaptoundecanoic acid (MUA) self-assembled monolayer (SAM). The modified surfaces were characterized by cyclic voltammetry (CV).The efficiency of these modified surfaces for the electrochemical oxidation of DA and EP was investigated and compared. The peak potential for the oxidation of each analyte at the different electrode surfaces was determined by square-wave voltammetry (SWV).The dependence of the sensitivity of the electrodes for the detection of the catecholamines on the applied potential was also measured. The SAM-based electrodes showed better selectivity for detecting DA in the potential range between 0.2 and 0.4 V versus Pt (QRE). However, higher sensitivity and linearity were observed for the film-based electrodes. 相似文献
36.
Xiao Tang Min Gao Haosu Luo Jiefang Li Dwight D. Viehland 《Journal of the American Ceramic Society》2020,103(6):3726-3731
Epitaxial CoFe2O4 (CFO) and SrRuO3 (SRO) nanopillar heterostructures were deposited on Pb(Mg1/3Nb2/3)0.70Ti0.30O3 (PMN-30PT) single crystal substrates by switch pulsed laser deposition (SPLD). Since the CFO nanopillars are insulating, and the SRO matrix conductive, this self-assembled nanopillar heterostructure served as a patterned electrode on PMN-PT, which then enhances the dielectric and piezoelectric constant of the substrate. Cross-sectional electron microscopy images revealed the formation of a nanopillar heterostructure layer with CFO nanopillars within a SRO matrix. AFM and XRD revealed good topography and epitaxy, indicating a high quality SRO-CFO self-assembled nanopillar structure. Using a SRO-CFO thin film patterned electrode, PMN-PT was found to have a notably higher (30%) dielectric constant with increasing electric field and enhanced transverse broadening in reciprocal spacing mapping (RSM) scans. 相似文献
37.
To study the configuration and conductivity effects on micro?scale methane?air flames by electric field and iron wind, different electric field forces and iron winds are generated by needle, circle and... 相似文献
38.
A new type of bamboo biochar (BC) loaded TiO2-SnO2 particle electrode was prepared and characterized by SEM, FT-IR, BET and XRD for efficient treatment of the coking wastewater in a three-dimensional electrochemical reaction system(3DERs). The results showed that bamboo biochar had a dense microporous space structure, and a significant amount of Ti-Sn oxides existed on the surface and in the interior of the BC. The removal rates of COD and DOC in coking wastewater reached to 73.96% and 66.72% respectively, and UV254 reduced from 6.65 cm-1 to 3.00 cm-1 by the electrolysis treatment of 150 min at the current density of 30 mA/cm2. The three-dimensional fluorescence spectra indicated that the most of the soluble organic compounds and soluble microbial by-products were degraded and transformed. The addition of Ti and Sn enhanced the efficacy of the electrooxidation, electro-adsorption and electrocatalytic behavior of the BC particle electrodes, which improved the treatment effect on coking wastewater in the 3DERs. In addition, this study provides the possibility of basic research for the engineering practice of electrochemical oxidation treatment of coking wastewater. 相似文献
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