Physical Chemistry Commons^™

Nanocomposite Thin Films Of Au Nanoparticles Embedded In Yttria-Stabilized Zirconia For Plasmonic-Based Harsh Environment Gas Detection, Phillip Henry Rogers

Legacy Theses & Dissertations (2009 - 2024)

Increased health concerns due to the emission of gases linked to the production of tropospheric ozone by petroleum based fuel burning engines has resulted in the codification of more stringent emissions regulations domestically. Emissions regulations on commercial jetliners are one of the areas to be met with stricter standards. Currently there is not a sensing technology that can detect the emissions gases in the exhaust stream of a jet turbine engine with lower detection limits that meet these standards.

One-Pot Synthesis Of Anionic (Nitrogen) And Cationic (Sulfur) Codoped High-Temperature Stable, Visible Light Active, Anatase Photocatalysts, Suresh Pillai, Declan Mccormack, Steven Hinder, Pradeepan Periyat

Articles

No abstract provided.

Spectroscopic Investigation Of Palladium-Copper Bimetallic Systems For Pem Fuel Cell Catalysts, Timo Hofmann

UNLV Theses, Dissertations, Professional Papers, and Capstones

One of the main barriers to commercialization of polymer electrolyte membrane fuel cells systems is cost, which is largely due to the need of platinum (Pt)-containing catalysts. In this thesis we investigate bimetallic systems consisting of a base metal (copper) and a noble metal (palladium) that, as an alloy on the nanoscale, mimic the electronic properties that make Pt desirable as a catalyst.

We present a detailed investigation of the electronic structure of carbon-supported Pd/Cu nanoparticle catalysts, model bilayer thin film systems, alloys, and various metal reference samples. We have investigated the valence band structure of the catalysts using a …

Studies Of Surface Diffusion In Pemfc Electrodes, Jiang-Shui Luo, Jian Chen, Bao-Lian Yi, Chuan-Sin Cha, Hua-Min Zhang

Journal of Electrochemistry

A PEMFC electrode consisting of dual-layer catalyst layer(CL) was fabricated in this work. The outer CL was Nafion-free,while the inner CL was Nafion-bonded. The effects of Pt/C catalyst in the outer CL that did not contact with Nafion on the current generation in PEMFC electrodes were investigated. Cyclic voltammetric studies indicated that the Pt/C catalyst in the outer CL without direct contact with Nafion was still electrochemically active in taking part in the adsorption/desorption of hydrogen and the electrochemical oxidation/reduction of the oxygen-containing species occurring at the interface of "Pt/Nafion" in the inner CL. The polarization curves showed that the …

Voltammetric Determination Of Iodate Ion In Table Salt By Carboxylic Carbon Nanotubes Modified Carbon Paste Electrode, Jun-Hua Li, Fu-Xing Zhang, Jian-Qiu Wang, Zhi-Feng Xu, Rong-Ying Zeng, Yan Yu

Journal of Electrochemistry

A highly-sensitive and mercury-free method of determining iodate ion in table salt was established based on carboxylic carbon nanotubes modified carbon paste electrode.In 0.1 mol/L NaOH solution,there was a sensitive cathodic stripping peak on voltammograms.The stripping peak potential was-0.52 V when accumulation time of IO-3 at the modified electrode was 60 s and the potential scan rate was 300 mV/s.There was a good liner relationship between the peak current and IO-3 concentration in the range of 8.0×10^-10 ～ 5.0×10^-8 mol/L and 1.0×10^-7 ～ 3.0×10^-6 mol/L with the correlation coefficient of 0.999 and 0.998,respectively.The detection limit was …

The Hydrothemal Synthesis Of Nanoscale Lifepo4 And Its Electrochemical Performance, Si-Min Wang, Ming-Sen Zheng, Quan-Feng Dong

Journal of Electrochemistry

The cathode materials of LiFePO₄ were prepared via a hydrothermal reduction method using FeCl₃ as Fe source and iron as a reducing agent.The results showed that ferric salt could be reduced to ferrous salt completely under the hydrothermal condition and pure-phase LiFePO₄ was obtained based on the test results of XRD and FTIR. Carbon-coated LiFePO₄ was synthesized by pyrolysisng glucose at high temperature. The morphologies of pure LiFePO₄ displayed cluster-like while the LiFePO₄/C displayed sphere-like particles. The electrochemical test showed that the LiFePO₄/C had good rate performance,while LiFePO₄ delivered much …

Preparation And Optical Transmission Of The Zno Nanorod Array Films, Feng Ye, Jing-Jing Li, Tong-Tao Wang, Yong-Liang Wang, Yun Liu, Xin-Dong Wang

Journal of Electrochemistry

By using a galvaostatic electrodeposition method in the ZnCl₂ solution,the highly oriented ZnO nanorod array films have been successfully prepared on ITO substrate after the pretreatment with ZnO nanoparticles.And they were characterized by scanning electron microscope,X-ray diffraction and transmittance spectra.The results indicated that the ZnO nanorod arrays grew along(001) direction with an orientation perpendicular to the substrate.When the wavelength of incident was over 380 nm,the ZnO nanorod arrays showed high optical transmission of above 95%.Furthermore,the band gap became narrower.

Electrochemical Synthesis, Characterization And Fluorescence Property Of Nano Na2Sif6, Guo-Xu Qin, Xin-Jun Wan, Xi-Mei Yuan, Dao-Bao Chu

Journal of Electrochemistry

The nano TiO₂ film was prepared by sol-gel process and characterized with X-ray diffraction(XRD) and scanning electron microscope(SEM).It was found that the average size of pore diameter was about 80 nm for the nano TiO₂ film.The Nano Na₂SiF₆ was synthesized by electrochemical deposition on the nanoporous film electrode and characterized with XRD and transmission electron microscope(TEM).The result showed that the average size of nanoparticle was 20 nm for the nano Na₂SiF₆.The fluorescence property of nano Na₂SiF₆ was also studied briefly.The result indicated that the nano Na₂SiF …

An Hap/Nanosilver Coating Prepared By Electrochemical Deposition And Its Antibacterial Characterization, Zhi-Wang Geng, Hui Wang, Chang-Jian Lin

Journal of Electrochemistry

The silver nanoparticles were prepared by sodium citrate reduction of AgNO₃.The nanoparticles were electrophoretic deposited on titanium, followed by the electrolytic deposition of hydroxyapatite(HAp). It is revealed, by the high-resolution transmission electron microscopy(HRTEM), that the diameters of nanosilver particles ranged from 5nm to 20nm. The XPS and XRD indicated the coating consisting of silver and HAp. According to the SEM images and antibacterial test, it is demonstrated that when the concentrations of the electrophoretic solution became higher more silver particles were depostited, and the antibacterial property improved. However, the particles aggregated on titanium greatly when the concentration exceeded …

Design And Fabrication Of The High Efficient Platinum-Nanoporous Gold Catalysts, Zhao-Na Liu, Jin-Tao Zhang, Fang Tian, Peng-Peng Liu, Hou-Yi Ma, Yi Ding

Journal of Electrochemistry

The nanoporous gold(NPG) electrodes with uniform pore sizes and ligaments were prepared by using a simple dealloying method.The as-prepared NPG showed high catalytic activity towards the oxidation of formic acid and formaldehyde.After tiny amount of platinum was deposited onto the NPG substrate,not only the structure stability of NPG was greatly improved,but also the Pt-Au bimetallic catalysts displayed the better catalytic activity and the stronger poison resistance towards the electrooxidation of small organic molecules than the bulk platinum due to synergistic effect between Au and Pt compositions.

Study On Electrocatalytic Oxidation Of Salbutamol At Carbon Nanotubes Modified Electrode, Ying-Liang Wei, Lu-Ping Zhang, Chen Shao, Hui Feng, Xian-Li Li

Journal of Electrochemistry

The multi-wall carbon nanotubes(MWNT) were dispersed successfully into water in the presence of dihexadecyl hydrogen phosphate(DHP) and a stable well-distributed suspension.A was formed sensor based on the multi-carbon nanotubes film coated glassy carbon electrode was developed.The electrochemical response of salbutamol was studied by square wave voltammetry.The oxidation peak potential of salbutamol at the modified electrode was observed at 0.604 V,which shifted about 40 mV negatively.The peak current increased 4.5 folds,in contrast to that at a bare electrode.Under optimal measurement conditions,there was a good linear relationship between the peak current(Ipa) and salbutamol concentration(C) in the range from 8.3 × 1 0 …

Electrocatalytic Oxidation Of Salicylic Acid At Novel Gold Nanoparticle-Modified Glassy Carbon Electrode, Yan-Ping Cui, Chang-Zhu Yang, Jian Huang, Wen-Hong Pu, Jing-Dong Zhang

Journal of Electrochemistry

A gold nano-particles modified glassy carbon electrode(GNP/GCE) was prepared by the"seed-mediated gold nano-particles growth method".Field emission scanning electron microscopy,ultraviolet-visible(UV-vis) spectroscopy analysis and electroalaylsis were employed to study the morphology and electrochemical performances.The resulting electrode showed excellent electro-catalytic activity toward the oxidation of salicylic acid and the response sensitivity was 1.8 fold than that obtained on GCE.Good linear relationship was obtained between response current and salicylic acid concentration in the range of 5.0 × 10^-7 ~8.0 × 10^-5 mol/L,which could be used in the detection of trace salicylic acid.

Corrosion Inhibition Of Self-Assembled Films On Iron By Electrochemical Impedance Spectroscopy, Yuan-Yuan Feng, Shen-Hao Chen, Juan-Juan Zhou, Wen-Juan Guo

Journal of Electrochemistry

The self-assembled films of tetradecylamine were formed on iron surface, and the inhibition ability of which for iron corrosion in 0.5 mol/L H₂SO₄ solutions was studied by electrochemical impedance spectroscopy technique. Results indicated that longer immersion time would result in stronger inhibition ability of the films. The maximal inhibition efficiency(IE) of the tetradecylamine films was 68.7%. When the tetradecylamine films were modified by dodecylthiol, the mixed films became denser and more stable, thus the inhibition ability increased remarkably. The η of the mixed films increased to 78.2%.

Structure And Property Of Molecular Self-Assembled Membrane With Zirconium Ion, Tian-De Wang, Rong Wang, Xia-Qin Wu, Zhi-Gang Guo, Wei-Wei Ji

Journal of Electrochemistry

According to the complex interaction between dodecyl phosphonate and stainless steel surface as well as the zirconium ion,the self-assembled monolayer and double-layer dodecyl phosphonate modified 304 type stainless steel electrode were prepared.The electrodes were characteristiced by static contact angles and electrochemical polarization methods.The results suggested that the double-layer modified stainless steel electrode had better corrosion inhibition effect than the monolayer modified electrode.

Preparation And Catalytic Activity Of Nanostructured Pd And Au-Pd Thin Films, Cui-Cui Qiu, Jin-Tao Zhang, Fang Tian, Hou-Yi Ma

Journal of Electrochemistry

The nanostructured Pd thin films were directly formed on the glassy carbon electrode(GCE) substrates by using potential cycling method.The as-prepared Pd thin films deposited onto the GCE were able to absorb enough amount of hydrogen in acidic solutions at the cathodic potentials more negative than the hydrogen evolution potential.Moreover,the absorbed hydrogen could be used as the reducing agent to reduce gold(III) ions to Au nanoclusters,thereby forming bimetallic Au-Pd thin films on the GCE substrate.SEM and cyclic voltammetry characterization demonstrated that the Au-Pd thin films display much higher catalytic activity towards the electro-oxidation of ethanol than the pure Pd thin films.

Carbon Nanotube Array Electrodes Based Supercapacitors With 3.5v Working Voltage, Hao Zhang, Gao-Ping Cao, Yu-Sheng Yang, Zhen-Nan Gu, Bin Xu, Wen-Feng Zhang

Journal of Electrochemistry

The carbon nanotube arrays(CNTA) were grown directly on the substrates of Ta and stainless steel by chemical vapor deposition.The button-like supercapacitors were fabricated based the CNTA electrodes.The electrochemical performance of CNTA based supercapacitors presentsed high working voltage(3.5 V),long cycle life,and good rate capability.The power and energy densities are were 928 kW·kg^-1 and 19 Wh·kg^-1,respectively(based on the mass of CNTA).

Preparation And Photoelectrochemical Properties Of Fe-Doped Tio2 Nanotube Arrays, Jing Li, Lan Sun, Hui-Fang Zhuang, Cheng-Lin Wang, Rong-Gui Du, Chang-Jian Lin

Journal of Electrochemistry

The Fe-doped TiO₂ nanotube arrays were fabricated in Fe(NO₃)₃-HF mixing solutions by electrochemical anodic oxidation method,and characterized by FESEM,Raman,XPS and DRS.The effect of Fe concentratiions on photoelectrochemical property of the arrays was also investigated.The diameters and lengths of Fe-doped TiO₂ nanotube arrays were 50~90 nm and about 200 nm,respectively.Compared with the undoped TiO₂ nanotube arrays,the absorption edge of Fe-doped TiO₂ nanotube arrays appeared red shifting.The more Fe content,the larger red shifting,in addition,the photocurrent of Fe-doped TiO₂ nanotube arrays increased obviously.

Cyclic Voltammetry And In Situ Ftir Studies Of Cyanide Adsorption On Nanostructured Au Film Electrode In Alkaline Solutions, Chun-Hua Zhen, Chun-Jie Fan, Shi-Gang Sun

Journal of Electrochemistry

The adsorption of cyanide(CN^-) on electrodes of nanometer scale thin film of gold supported on glassy carbon(nm-Au/GC) in alkaline solutions were investigated using cyclic voltammetry and in situ FTIR spectroscopy.It has revealed that the electrodeposited nanostructured Au thin film exhibited AIREs(abnormal infrared effects) for CN^-adsorption,which manifested 3 nonlinear IR spectral features: inversion of the direction of CN^-band,enhancement of IR absorption of adsorbed CN-species(about 39.2 folds) and increase in the FWHM(full width at half maximum) of CN^-band.

Quick Tester With Usb Interface For The Corrosion Protection Properties Of Organic Coating, Xiang-Dong Zhuo, Chang-Jian Lin

Journal of Electrochemistry

According to the principle of multiple dynamic potential scaning polarization,a quick tester with USB interface for the fast study of corrosion resistance properties of organic coating/ metal system has been developed.This tester is portable,facile,practical,and has a strong function for data collection and data treatment.It is not only suitable for the accelerated test in laboratory,but also for the quick test and evaluation to the corrosion resistance of the organic coating/metal system in industrial spots.

In Situ Measurement Of Chloride Concentration And Ph Distribution In The Crevice During The Crevice Corrosion Of Copper Electronic Board, Min Zhang, Xiang-Dong Zhuo, Chang-Jian Lin

Journal of Electrochemistry

Although the crevice corrosion of metals had been extensively studied in the past years,it remained lack of direct experimental information of the micro chemical environments and electrochemical conditions inside the corroding crevice.The distribution of chloride concentration and local pH in the occluded area are the most crucial factors in development of crevice corrosion.The array probes in one dimension of Ag/AgCl and IrO₂ array were developed in this work to in situ follow the distribution of chloride concentration and local pH in the occluded area during the crevice corrosion propagation.Based on a designed simulated crevice corrosion system in 0.5mol/L NaCl …

A Study On Supercapacitor Based On Aligned Carbon Nanotubes, Xiao-Yan Ye, Yan-Zhi Wang, Hai-Yan Song, Zhuo Sun, Pin-Gang He, Yu-Zhi Fang

Journal of Electrochemistry

Large scale vertically aligned carbon nanotubes(ACNTs) with uniform length and diameter were prepared by the pyrolysis of iron(Ⅱ) phthalocyanine at low pressure.The ACNTs were activated by electrolyte-activation,acid-activation or electrochemical activation.The performance of the capacitor based on activated ACNTs was characterized by cyclic voltammograms which was of rectangular shape,impedence spectroscopy in which the phase is above 80° and the result specific capacitance was 16～32 F/g,which suggest that the ACNTs are the promising material for the supercapacitor.

Determination Of Malathion Based On Carbon Nanotubes Modified Electrode Incorporating Acetylcholinesterase, Lu Zhang, Yao-Dong Zhang, Hong-Lan Qi

Journal of Electrochemistry

A biosensor for determination of organophosphorus pesticide based on the acetylcholinesterase and multi-wall carbon nanotubes modified electrode is fabricated.Under the optimal conditions,the chronoamperometric current at +0.70V(vs.SCE) increased linearly with the concentration of malathion in the range from 6.0×10^-10 to 6.0×10^-9 mol·L^-1 with a detection limit of 1.0×10^-10 mol·L^-1.The recoveries of malathion in lake water is 97% to 105% determinated by this method.

Study On Electrochemical Impedance Spectroscopy Of Carbon Steel Eroded In Methyldiethanolamine Solution, Dong-Ping Wei, Rong-Zong Hu, Dan-Mei Pan, Wei-Xiong Huang, Rui Dong

Journal of Electrochemistry

Corrosion behavior of carbon steel in methyldiethanolamine(MDEA) solution was investigated by Electrochemical Impedance Spectroscopy(EIS).The results were showed that the corrosion rate of carbon steel in solution containing dissolved oxygen is higher than that in solution removed of dissolved oxygen before cathodic activation.They were reversed after cathodic activation.The corrosion rate is increased at first and then decreased when the concentration of MDEA is increased in the blank solutions.In the simulated solutions containing quantities of!heat-stable salts(HSS),the corrosion rate is decreased monotonously with increase of the MDEA concentration.As anodic polarization potential is increased,the EIS of carbon steel in HSS simulated solution showed characteristics …

Preparation And Investigations On The Tio2 Nanotube Arrays For Cathodic Protection Of 316l Stainless Steel, Jing Li, Hong Yun, Chang-Jian Lin

Journal of Electrochemistry

A highly ordered TiO₂ nanotube layer was fabricated by potentiostatic anodization of pure titanium in fluorinated electrolyte solutions. The structure and composition of the as-prepared TiO₂ nanotubes were characterized by SEM and XRD.The TiO₂ nanotubes show a stronger absorption in the ultraviolet(UV) light range. The performances of photogenerated cathodic protection and the photoelectrochemical response for the TiO₂ nanotube layers under illumination and dark conditions were evaluated through the electrochemical measurements. It is found that the open-circuit potentials of 316 SS coupled with the TiO₂ nanotubes layers shift negatively under UV light irradiation(λ<380nm). It is indicated that the TiO₂ nanotubes arrays …

Growth Mechanism And Morphology Of Electrodeposited Micro-Nanocrystalline Iron, Qiao-Xin Zhang, Jia-Ming Zhang, Li-Ning Yang

Journal of Electrochemistry

Effects of current density,reaction temperature,electrolyte concentration and surfactant on the electrochemical deposition of micro-nanocrystalline iron were studied.Morphologies and structures of the samples were characterized by SEM and XRD,the results showed that the electrodeposits is slice α-Fe under little current and the density,lower temperature and higher concentration,and the dentritic α-Fe is under opposite conditions,but the influence from surfactant is unconsicously.Moreover,the growth mechanism of the electrodeposits was also analysed here.

Study On The Nano Diamond Stable Water Disperse System And Applying In Composite Chromium Plating, Lai-Xiang Zhang, Hong-Bo Xie, Xue-Kui Ma, Guo-Wu Zhao, En-Cheng Yu, Jia-Zhi Wang

Journal of Electrochemistry

The nano diamond stable water disperse system was studied.The low-bublles sulfonic anion sufcace active agent had been choosed out for this system.The affect of different physics agitation mothed on the water separate system stablity were conpared.The nano diamond stable water separate system had been applied to the composite chromium electroplating on this tests.The depositing speed,hardnees and wearing capacity of plating layer were tested.And the metallography structure of plating layer was charasterized by SEM.The test results and reaction princeple were discussed.

Fabrication And Charaterization Of Nitrogen-Doped Tio2 Nanotube Array And Its Visible Light Activity, Hui-Fang Zhuang, Yue-Kun Lai, Jing Li, Lan Sun, Chang-Jian Lin

Journal of Electrochemistry

Nitrogen-doped TiO₂ nanotube array was fabricated by an electrochemical anodic oxidation followed a wet process.XPS result indicates that the nitrogen atoms were doped into lattice of TiO₂ nanotubes.The UV-Vis spectra show that the photoabsorption of N-doped TiO₂ nanotube array film is enhanced in the visible light region.Compared with the TiO₂ nanotube array film,the N-doped TiO₂ nanotubes exhibite a higher photocatalytic activity which is evaluated by the decomposition rate of methyl orange using the tungsten-halogen lamp as light source.

Electrocatalytic Oxidation Of Methanol At The Nano Ni-B Amorphous Alloy Powdermicroelectrode, Yi-Xiong Zheng, Shi-Bing Yao, Shao-Min Zhou

Journal of Electrochemistry

Electrocatalytic oxidation of methanol at the nano Ni-B amorphous alloy powder-microelectrode in alkaline media was studied by using cyclic voltammetry.Compared to the highly preferred orientation(220) nickel electrode,The onset potential of methanol electrooxidation at the nano Ni-B microelectrode is negatively shifted about 0.04V,and the current density is increased approximately by 2 orders of magnitude.Thus,the nano Ni-B microelectrode has very strong electrocatalytic activity for the oxidation of methanol.The kinetic parameters were determined with the steady polarization curves.The results show that the rate constants for both the oxidation of Ni(Ⅱ) to Ni(Ⅲ) and the reduction of Ni(Ⅲ) to Ni(Ⅱ) at the nano Ni-B …

Pdms Regularly Superhydrophobic Surfaces Prepared By Icp Etching Silicon Model, Run-Xiang Zhang, Yu-Long Zhang, Hua-Shui Lin

Journal of Electrochemistry

A series of different dimensions regularly micropillar array hydrophobic Poly(dimethylsiloxane)(PDMS) surfaces were obtained by peeling off PDMS which was poured onto the silicon models.The silicon models were prepared by ICP etching technology.The results indicate that the water contact angle(WCA) was increased with the size and the height of the mocropillar,decreased with increasing the distance of the mocropillar when the height of the micropillar was relative small;if the height of the micropillar was relative big,WCA was decreased with increasing the size of micropillar,meanwhile,the distance of the micropillar was a complex factor to WCA,and the height of the micropillar have little influence.The …

The Syntheses And Electrochemical Performance Of Nano-Mno2 For Supercapacitor, Jun Ma, Ming-Sen Zheng, Quan-Feng Dong

Journal of Electrochemistry

Nano-manganese dioxide were prepared by two different methods which are low temperature solid reaction and chemical deposition.The products were characterized by XRD,SEM,BET and constant current charge-discharge tests.The result shows that there is a close relationship between specific capacitance and BET surface areas.Meanwhile the specific capacitance was impacted little by the structure of the nano-manganese dioxides.However,the product performance of high rates,was influenced by structure,the higher rate can be obtained with the more perfect crystal structure.