Nanoscience and Nanotechnology Commons^™

Cyclic Voltammetric And In-Situ Ftir Spectroscopic Studies Of Adsorption And Reduction Of No On Electrode Of Pt Nanoparticles, Qian Cheng, Yan-Xia Jiang, Dong-Mei Zeng, Shi-Gang Sun

Journal of Electrochemistry

Adsorption and reduction of NO on electrode of Pt nanoparticles in acid solutions were studied by means of cyclic voltammetry(CV) and in-situ FTIR spectroscopy.The results indicated that the reduction of NO is a complicated process including the adsorption of NO on electrode surface.Two types of surface-bonded NO were determined on Pt nanoparticles.The weakly adsorbed NO was reduced between 0.6 V and-0.05 V,which yielded nitrous oxide(N2O) and ammonium(NH+4) as products;while the strongly bonded NO was reduced at more negative potentials between-0.05V and-0.15V,producing only NH4+ species.

Enhanced Visible Light Photoelectrochemical Performances With Nitrogen Doped Tio_2 Nanowire Arrays, Xiao-Jun Lv, Yue-Ming Li, Hao Zhang, Da Chen, Hensel Jennifer, Z Zhang Jin, Jing-Hong Li

Journal of Electrochemistry

Self-organized anodic anatase TiO2nanowire arrays doped with nitrogen have been successfully fabri-cated and their photoelectrochemical(PEC) properties have been characterized and found to be substantially im-proved compared to undoped nanowires or commercial P25 nanoparticles.Photocurrent measured with monochro-matic incident light showed that the incident photon-to-current efficiency(IPCE,%) values of nanowire arrayelectrodes with or without N-doping were obviously higher than that of commercial P25 nanoparticle electrodes,and nitrogen-doped TiO2nanowire arrays(NTNA) had noticeable absorption in the visible region.The NTNAelectrodes showed the highest photocurrent density and power conversion efficiency under 100 mW/cm2visiblelight illumination.A maximumolphotoconversion efficiency of 0.52% was achieved for the NTNA sample at anapplied potential of …

Synthesis And Electrocatalytic Properties Of Ni-Pd/C Catalysts With Pd-Enriched Surface, Yu-Mei Chen, Zhi-Xiu Liang, Sheng-Li Chen

Journal of Electrochemistry

The Ni-Pd alloy catalysts with Pd-enriched surface were synthesized through a modified polyol process.The synthesized materials were investigated by XRD and electrochemical methods,and tested as electrocatalysts for CH3OH-tolerant oxygen reduction.The results indicated that the synthesized Ni-Pd nanoparticles possess multiple phases containing Pd-Ni alloy and pure Ni.Comparing with Pd/C,the prepared Ni-Pd/C nanoparticles exhibited better resolved voltammetric peaks between the hydrogen absorption and adsorption,and positively shifted current peaks for the reduction of Pd oxide.The prepared Ni-Pd alloys with Pd-enriched surface have significantly enhanced ORR activity and improved CH3OH tolerance as comparing with Pd/C catalysts.

Preparation Of Pt Nanoflower/Zno Composites Arrays And Their Electrocatalysis For Methanol Oxidation, Li Gao, Yi-Feng E, Lou-Zhen Fan

Journal of Electrochemistry

The Pt nanoflower/ZnO(PtNF/ZnO) nanorod composites arrays were electrochemically prepared by controlling the hydrophobicity and the hydrophilicity of ZnO nanorods arrays.The Pt nanoflowers grew on the tip of ZnO nanorods,which maintain the vertical array of Zno nanorods with a high degree of size uniformity and high surface area.Compared with Pt nanoparticle covered ZnO nanorod arrays,which were prepared by controlling the hydrophilicities of ZnO nanorods and Pt nanoparticles,the PtNF/ZnO displayed highest electrocatalytic activities for the oxidation of methanol.

Progresses In Electrocatalysis Of Nanomaterials—Tuning The Surface Structure And Property Of Electrocatalysts, Yan-Xia Jiang, Na Tian, Zhi-You Zhou, Sheng-Pei Chen, Shi-Gang Sun

Journal of Electrochemistry

The property of an electrocatalyst depends strongly on its surface structure.The study of surface structure-catalytic functionality is the base of design and preparation of electrocatalysts of high activity,high stability and high selectivity at microstructure level.In this paper,based mainly on our results concering hydrogen and oxygen adsorption-desorption,ethylene glycol oxidation and CO2 reduction,the research progresses in tuning the surface structure and property of electrocatalysts are summarized.This paper overviews firstly the cyclic voltammetric characteristics,electrocatalytic properties of platinum single crystal planes lying on different crystallographic zones of the unit stereographic triangle of face-centered cubic(fcc) metals.Next,the innovation of electrochemical methods to control the surface structure …

Complex Reduction Preparation Of Carbon Supported Pd Nanoparticle Catalyst And Its Electrocatalysis For Formic Acid Oxidation, Wei He, Yong-Yin Kang, Chong Du, Zhi-Qing Zou, Xiao-Gang Zhang, Hui Yang

Journal of Electrochemistry

A simple procedure involved the complexing of PdCl2 with sodium citrate followed by ethylene glycol reduction has been employed for the preparation of carbon-supported Pd nanoparticles(Pd/C).The XRD and TEM characterizations indicate that Pd nanoparticles with a small particle size were well-dispersed on carbon support.The mean particle sizes of the Pd/C catalysts were found to be increased from 2.7 to 5.8 nm with heat-treatments at different temperature.The mass activity of the Pd/C catalyst for formic acid electrooxidation increased with the decrease in Pd particle size.However,the specific activity increased with Pd particle size.Furthermore,the Pd/C catalyst with a particle size of ca.3.6 nm …

Electrocatalytic Oxidation Of Glucose On Cnt/Nanocrystlline Tio_2-Pt Complex Film Electrode In Ionic Liquids, Dao-Bao Chu, Long-Wu Zha, Shu-Xi Wang, Jian Wang, Ying Xiao, Yuan-Yuan Hou, Jian-Guo He, Xue-Jiao Zhang

Journal of Electrochemistry

Using ionic liquid [EMI]BF4 as the electrolyte,the electrocatalytic oxidation of glucose on carbon nanotubes/nanocrystlline TiO2 film loaded on Pt (CNT/nanoTiO2-Pt) complex film electrode was investigated by cyclic voltammetry. The results found that the CNT/nanoTiO2-Pt complex electrode had high catalytic activity to the electrochemical oxidation of glucose in ionic liquids and the oxidation potential was -0.46 V. The best effect of glucose oxidation was obtained with the volume ratio of ionic liquid to water being 3∶1. The process of electrodic reaction process was concentration polarization controlled.

Synthesis And Characterization Of Sulfur-Carbonnanotubes As Cathode Of Lithium/Sulfur Rechargeable Battery, Rui Du, Zhong-Zhi Yuan

Journal of Electrochemistry

A carbon-containing composite was synthesized by heating element sulfur and carbon nanotubes. The sulfur-carbonnanotube composites were characterized by X-ray diffraction,SEM,Brunauer-Emmett-Teller.The electrochemical property was characterized by cyclic voltammetry,constant current charge and discharge.It was revealed that the sulfur-carbonnanotube cathode 2016-type coin cells exhibited a good electrochemical property with the initial dicharge specific capacity up to 680 mAh/g and a stable capacity approximately 500 mAh/g after 30 cycle numbers.

Ultra-Thin Super High Frequency Two-Port Aln Contour-Mode Resonators And Filters, Matteo Rinaldi, Chiara Zuniga, Chengjie Zuo, Gianluca Piazza

Matteo Rinaldi

This paper reports on the demonstration of a new class of ultra-thin (250 nm thick) Super High Frequency (SHF) AlN piezoelectric two-port resonators and filters. A thickness field excitation scheme was employed to excite a higher order contour extensional mode of vibration in an AlN nano plate (250 nm thick) above 3 GHz and synthesize a 1.96 GHz narrow-bandwidth channel-select filter. The devices of this work are able to operate over a frequency range from 1.9 to 3.5 GHz and are employed to synthesize the highest frequency MEMS filter based on electrically self-coupled AlN contour-mode resonators. Very narrow bandwidth (~ …

Dna-Decorated Carbon Nanotubes As Sensitive Layer For Aln Contour-Mode Resonant-Mems Gravimetric Sensor, Chiara Zuniga, Matteo Rinaldi, Samuel M. Khamis, Timothy S. Jones, A T. Johnson, Gianluca Piazza

Matteo Rinaldi

In this work a nano-enabled gravimetric chemical sensor prototype based on single-stranded DNA (ss-DNA) decorated single-walled carbon nanotubes (SWNT) as nano-functionalization layer for Aluminun Nitride (AIN) contour-mode resonant-MEMS gravimetric sensors has been demonstrated. Two resonators fabricated on the same silicon chip and operating at different resonance frequencies, 287 and 450 MHz, were functionalized with this novel bio-coating layer to experimentally prove the capability of two distinct single strands of DNA bound to SWNT to enhance differently the adsorption of volatile organic compounds such as dinitroluene (DNT, simulant for explosive vapor) and dymethyl-methylphosphonate (DMMP, a simulant for nerve agent sarin). The …

Nanoenabled Microelectromechanical Sensor For Volatile Organic Chemical Detection, Chiara Zuniga, Matteo Rinaldi, Samuel M. Khamis, A. T. Johnson, Gianluca Piazza

Matteo Rinaldi

A nanoenabled gravimetric chemical sensor prototype based on the large scale integration of single-stranded DNA (ss-DNA) decorated single-walled carbon nanotubes (SWNTs) as nanofunctionalization layer for aluminum nitride contour-mode resonant microelectromechanical (MEM) gravimetric sensors has been demonstrated. The capability of two distinct single strands of DNA bound to SWNTs to enhance differently the adsorption of volatile organic compounds such as dinitroluene (simulant for explosive vapor) and dymethyl-methylphosphonate (simulant for nerve agent sarin) has been verified experimentally. Different levels of sensitivity (17.3 and 28 KHz µm^2/fg) due to separate frequencies of operation (287 and 450 MHz) on the same die have also …

5-10 Ghz Aln Contour-Mode Nanoelectromechanical Resonators, Matteo Rinaldi, Chiara Zuniga, Gianluca Piazza

Matteo Rinaldi

This paper reports on the design and experimental verification of Super High Frequency (SHF) laterally vibrating NanoElctroMechanical (NEMS) resonators. For the first time, AlN piezoelectric nanoresonators with multiple frequencies of operation ranging between 5 and 10 GHz have been fabricated on the same chip and attained the highest f-Q product (4.6E12 Hz) ever reported in AlN contour-mode devices. These piezoelectric NEMS resonators are the first of their class to demonstrate on-chip sensing and actuation of nanostructures without the need of cumbersome or power consuming excitation and readout systems. Effective piezoelectric activity has been demonstrated in thin AlN films having vertical …

Modulated Nanopores Using Pulse Anodization On Thin Aluminum, Mahesh Babu Gunukula

UNLV Theses, Dissertations, Professional Papers, and Capstones

Nanoporous anodic aluminum oxide has traditionally been made in one of two ways: "Mild Anodization (MA)" or "Hard Anodization (HA)". The former method produces self-ordered pore structures but it is slow and only works for a narrow range of processing conditions; the latter method, which is widely used in the aluminum industry, is faster but it produces films with disordered pore structures. Here we report a novel approach termed "pulse anodization" that combines the advantages of the MA and HA processes. By designing the pulse sequences it is possible to control both the composition and pore structure of the anodic …

Magnetic Sensors For Biodetection, Pranjali Vineet Sneha Deshpande

UNLV Theses, Dissertations, Professional Papers, and Capstones

The objective of thesis is to design magnetic sensor for detection of nanoparticles. Recently integrating the standard laboratory techniques into integrated system on chip is growing attention. Recent development is to combine magnetic markers and magnetoresistive sensors together in magnetic chip. In this thesis two magnetoresistive sensors were studied and designed.

By applying magnetic fields, magnetic nanoparticles can be manipulated on-chip, which can be utilized to pull the molecules to specific binding sites or to test the binding strength and distinguish between specifically and non-specifically bound molecules

Magnetoresistive sensors are compatible with the semiconductor industry which provides electronic signal directly …

Aln Contour-Mode Resonators For Narrow-Band Filters Above 3 Ghz, Matteo Rinaldi, Chiara Zuniga, Chengjie Zuo, Gianluca Piazza

Matteo Rinaldi

This paper reports on the design and experimental verification of a new class of thin-film (250 nm) Super High Frequency (SHF) laterally-vibrating piezoelectric microelectromechanical (MEMS) resonators suitable for the fabrication of narrow-band MEMS filters operating at frequencies above 3 GHz. The device dimensions have been opportunely scaled both in the lateral and vertical dimensions in order to excite a contour-extensional mode of vibration in nano features of an ultra-thin (250 nm) Aluminum Nitride (AlN) film. In this first demonstration two-port resonators vibrating up to 4.5 GHz were fabricated on the same die and attained electromechanical coupling, kt2, in excess of …

Patterning And Characterization Of Carbon Nanotubes Grown In A Microwave Plasma Enhanced Chemical Vapor Deposition Chamber, Mauricio Kossler

Theses and Dissertations

This research studies the growth of carbon nanotubes (CNT) from a nickel catalyst to be used on a field emission device. This thesis can be divided into three sections: the construction of a vacuum chamber for field emission testing, the design and fabrication of a triode structure to enable improved electron emission, and the pretreatment and growth of CNTs. To experimentally test the field emission of CNTs, a vacuum chamber must attain a vacuum of at least 10^-5 torr. Our vacuum chamber designed and built achieved a maximum, final pressure of 10^-8 torr. A triode structure was designed …

High Utilization Aupt Nanoparticles Supported On Mwcnts For Methanol Electro-Oxidation In Alkaline Medium, Xun Guo, Dao-Jun Guo, Xin-Ping Qiu, Li-Quan Chen, Wen-Tao Zhu

Journal of Electrochemistry

We synthesized gold-platinum electrocatalysts supported on multi-walled carbon nanotubes(MWCNTs) with high utilization by a simple one-step method.A high Pt loading series of bimetallic AuPt/MWCNTs catalysts were prepared by the improved ethylene glycol reduction method,and then were compared in terms of the electrocatalytic activity for methanol electro-oxidation using cyclic voltammetry(CV) and chronoamperometry in alkaline solutions.The structure of AuPt/MWCNTs was characterized by the transmission electron microscopy(TEM),X-ray diffraction(XRD) and energy-dispersive X-ray spectroscopy(EDS).The results showed that the AuPt/MWCNTs catalysts had high Pt utilization,uniform AuPt nanoparticles size and good electrocatalytic activity for methanol electro-oxidation.The effect of Au/Pt mass ratio on electrocatalytic activity was also investigated.The …

Photoelectrochemical Properties Of Tio_2 Nanoparticles, Jie Qu, Ying Li, Qi-Wei Jiang, Xue-Ping Gao

Journal of Electrochemistry

The protonated titanate nanoparticles were obtained at room temperature and subsequently calcined at different temperatures(300 ℃,400 ℃,500 ℃,600 ℃ and 700 ℃) in air.The obtained products were characterized by XRD,TEM and UV-Vis.It is found that the grain sizes of TiO2 nanoparticles calcined at 300 ℃ were about 20 nm,and increased gradually with the temperature rise.Photoelectric performance was measured with I～V curve and electrochemical impedance spectroscopy(EIS).The TiO2 nanoparticles obtained at 500 ℃ showed the best photoelectrochemical properties with a photovoltaic conversion efficiency of 6.39%,which is much higher than those at other temperatures.In addition,it is also demonstrated that the charge transfer resistance …

Nano-Sn/Hard Carbon Composite As Anode Material For Lithium Ion Batteries, Bing-Kun Guo, Jie Shu, Kun Tang, Ying Bai, Zhao-Xiang Wang, Li-Quan Chen

Journal of Electrochemistry

The tin(Sn) nano particles were embedded into the mesopores of hard carbon spherules(HCS) to form a composite anode material for lithium ion batteries.The structure of the obtained composite was characterized by X-ray diffraction(XRD) while its electrochemical performances were evaluated with galvanostatic cycling.It is found that the embedding Sn nanoparticles into porous HCS not only result in a composite material with high lithium storage capacity and capacity retention,but also increase the initial coulombic efficiency of the composite.Based on the infrared spectroscopic analysis,the enhanced initial coulombic efficiency is attributed to the inductive decomposition of the ROCO2Li species in the solid electrolyte interphase(SEI) …

Synthesis,Characteristics And Electrochemical Performance Of Nano-Sized Snco/Graphite Composites As Anode For Lithium Ion Batteries, Jin-Shu Cai, Ling Huang, Fu-Sheng Ke, Shi-Gang Sun

Journal of Electrochemistry

The nano-structural Sn-Co/graphite composites were prepared by chemical reduction of the alloy electroless deposition solution in graphite suspensions,and the composites were annealed at 500 ℃.The phase structure and surface morphology of the composites were measured by XRD、SEM and Raman.The results indicate that there were high dispersions and high loadings of Sn-Co nanoparticles on graphite by thermal treatment.Electrochemical lithium storage performance was studied preliminarily on the obtained samples.The graphite modified with the Sn-Co nanoparticles possessed a higher electrochemical reversible capacity than that of graphite during the charge and discharge process.The appetency between the Sn-Co nanoparticles and graphite can effectively reduce or …

Silicon Nanowires As Anode Materials For Lithium Ion Batteries, Yan-Peng Fu, Hui-Xin Chen, Yong Yang

Journal of Electrochemistry

The SiNWs electrodes were fabricated by coating and direct growth methods,respectively.The structure,morphology and electrochemical performance of such materials were characterized by XRD,SEM and charge-discharge tests.The results show that the electrodes prepared by direct growth method had higher capacity,better battery life and also displayed and excellent cyclability at higher currents.During the process of lithiation,the initial crystalline Si transformed to amorphous LixSi,and the average diameter of the SiNWs increased.Despite the large volume changed,the SiNWs remained intact and did not break into smaller particles.

Electrochemical Properties Of Functionalized Carbon Nanotubes And Their Applications In Analysis Of 6-Mercaptopurine, Bao-Yi Lu, Yan-Yan Lai, Hong Li

Journal of Electrochemistry

The electrochemical behaviors and adsorption properties of single-walled carbon nanotubes such as SWNT,SWNT-COOH,and SWNT-OH and multi-walled carbon nanotubes including MWNT,MWNT-COOH,and MWNT-OH modified at a graphite electrode have been investigated by using [Fe(CN)6]3-anion and [Co(phen)3]3+ cation.It was shown that shows good redox reversibility of [Fe(CN)6]3-/4-reactions on the existed carbon nanotubes(CNT) modified electrode.Based on the strong adsorptive property of [Co(phen)3]3+ on the CNT surface,the [Co(phen)3]3+/CNT modified graphite electrode can be obtained by progressive potential sweeping and developed to monitor quantitatively 6-mercaptopurine(6-MP).The adsorption capacity of [Co(phen)3]3+ on the multi-walled carbon nanotubes is higher than that of single-walled carbon nanotubes.For the carbon nanotubes with …

Effect Of Salts On The Electrospinning Of Poly(Vinyl Alcohol), Jonathan J. Stanger, Nick Tucker, Mark P. Staiger, Kerry Kirwan, Stuart Coles, Daniel Jacobs, Nigel Larsen

Jonathan J Stanger

Fibres with a diameter in the nanometer range were electrospun from aqueous poly(vinyl alcohol) (PVOH). In order to improve the mass deposition rate and decrease the final fibre diameter salts (NaCl, LiCl, LiBr and LiF) were added to the solution. The aim was to increase the charge density and hence increase the electrostatic forces on the fluid. It was found that with increasing salt concentration the charge density did increase. However the mass deposition rate was found to decrease and the final fibre diameter was found to increase. The decrease in mass deposition rate is explained by considering the concept …

Effect Of Charge Density On The Taylor Cone In Electrospinning, Jonathan J. Stanger, Nick Tucker, Kerry Kirwan, Stuart Coles, Daniel Jacobs, Mark P. Staiger

Jonathan J Stanger

A detailed understanding of charge density and its origins during the electrospinning process is desirable for developing new electrospinnable polymer-solvent systems and ensuring mathematical models of the process are accurate. In this work, two different approaches were taken to alter the charge density in order to measure its effect on the Taylor cone, mass deposition rate and initial jet diameter. It was found that an increase in charge density results in a decrease in the mass deposition rate and initial jet diameter. A theory is proposed for this behaviour in that an increase in charge density leads to the tip …

The Effect Of Electrode Configuration And Substrate Material On The Mass Deposition Rate Of Electrospinning, Jonathan J. Stanger, Nick Tucker, Andrew Wallace, Nigel Larsen, Mark P. Staiger, Roger Reeves

Jonathan J Stanger

Poly(vinyl alcohol) (PVOH) was electrospun using different methods to charge the polymer solution. A positive high voltage relative to the collecting electrode significantly increased the fibre deposition rate. Electron microscopy showed that approximately half of the increase in fibre mass was due to thicker fibres being deposited. The current flowing from the grounded electrode was measured to determine the charge carried on the PVOH jet. This showed that for a positive voltage charging condition there is a much larger current and hence more charge carriers generated in the PVOH solution. As a result, more mass is ejected from the Taylor …

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 …

Metal Induced Crystallization Of Silicon Thin Films, Sandeep Kumar Raju Sangaraju

UNLV Theses, Dissertations, Professional Papers, and Capstones

Low temperature crystallization of thin film silicon is important for many industrial applications including flat panel displays and silicon thin film solar cells. Unfortunately this remains a major challenge since crystallization temperature of silicon is above 1,000 degrees Celsius, thus limiting to substrates that can tolerate high temperatures. The inability to deposit crystalline thin films on glass substrates is the reason why flat panel display industry uses amorphous silicon for LCD active matrix displays. Thus the ability to deposit crystallized thin film silicon at low temperatures will have significant impact on thin film silicon applications. It has been observed that …