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Investigation of Au-Pd Alloy Nanowire's Fabrication and Sensing Performance for Glucose

Author: ZhangGaiXiu
Tutor: YuGang
School: Hunan University
Course: Physical and chemical
Keywords: Au-Pd Alloy Nanowires Morphology Composition AlternatingCurrent Deposition Glucose
CLC: O657.1
Type: Master's thesis
Year: 2013
Downloads: 33
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Abstract


Nano materials have offered advantages over their micro and macro analogs thatinclude decreased size, less power consumption, faster speeds, greater sensitivitiesand potentially lower cost, and widely use it on electron device and sensor. Now, moreand more method was used to synthetize nano materials with different property andstyle, such as nano particles, nano films, nanowires and nano channel and so on. Thispaper have sketched the latest developments of assemblying nano materials by vapordeposition, template method and alternating current deposition, and carefullydiscussed the method to obtain the noble nanowires through alternating currentdeposition. Noble materials has been widely concerned because of the catalyticefficiency and biocompatibility. We attained the Au-Pd alloy nanowires and used it asnon-enzyme glucose sensor to detect the glucose concentration by checking thecurrents changes in solution, this is a new exploration to apply noble materials onnon-enzyme glucose sensor.Au-Pd alloy nanowire have been deposited from aqueous solution by applyingvaried-frequency, and characterized the morphology, measured composition andcrystal phase by SEM, EDX and XRD. The experiment got the optimal condition toassembly thin and straight nanowires, and to obtain the changes law of nanowirescomposition and also to measure the performance of glucose sensor.The main results as follows:（1） By controlling the alternating current parameters, the influence of ionconcentration ratio of solution on nanowires morphology and compotion was carefullydiscussed. The concentration ratio of c PdCl2/cHAuCl4do not have effect on nanowiresmorphology, however, the concentration of solution can change the morphology ofnanowires. ion concentration ratio can greatly affected the nanowires composition, theratio of c PdCl2/cHAuCl4increased from-1 to6, the Pd mass fraction of alloy nanowiresvaried from2.5wt.%to68.5wt.%, but when cPdCl2/cHAuCl4up to5, the Pd massfraction do not change with the Pd2+ratio in solution, so, we keep c PdCl2/cHAuCl4=5/1to discuss the influence of alloy composition on electric field intensity and frequency.（2） The electric field intensity of alternating current can markedly changenanowires morphology and composition. The electric field have the critical value tosynthesize alloy nanowires. Applying1216Vppon2040μm of electrode spacing,when electric field intensity grow form0.1×106V m-1to0.4×106V m-1, nanowires with thin and less branch can be successfully obtained, meanwhile, the Pd massfraction of nanowires can change from25wt.%to67wt.%. So, controlling theelectric field can be used as a good method to synthesize nanowires with specialmorphology and controlled composition.（3） Frequency as a important parameter also play a key roles to change themorphology and composition. Under constant electric field and ion concentrationratio, varied-frequency deposition can get nanowires by the low-frequency fornucleation and high-frequency for growth. Through experiments, the low-frequency300Hz can be used for nucleation and high-frequency120MHz can be used forgrowth, this method can get a good linearity of nanowire arrays. With the increasinggrowth of frequency, the diameter of the alloy nanowires is gradually decrease, thebranch is less, the linearity is better. When the frequency change from3MHz to20MHz, the Pd mass fraction of alloy nanowires increased from60wt.%to80wt.%。（4） XRD proved that nanowires was face cubic crystal, gold and palladium isuniformly alloy phase structure and dendritic crystal structure. The lattice parametersof alloy nanowires changed along with the frequency of the AC current, and presenteda linear relationship, which confirmed the effect of composition in the context ofalternating current frequency on the alloy nanowires, the changes of the compositionof alloy nanowires affected the2of alloy nanowires, and then through thecalculation of Prague equation, the change of lattice constant of alloy materials can beobtained.（5） Au-Pd alloy nanowires can be made into glucose sensor. Nanowires have goodcatalytic activity and selectivity for glucose reduction. There is a linear relationshipbetween the square root of reduction and oxidation peak currents and scanning rate,which indicated that this is diffusion controlled process. Au-Pd alloy nanowire hadelectrocatalytic activity, high selectivity, sensitivity and reproducibility for glucose.This study has the following characteristics and innovations:（1） reveal the lawbetween electric field intensity and frequency on the synthesis of gold and palladiumalloy nanowires, and find the optimal range of electric field intensity and frequency tosynthesis of gold and palladium alloy nanowires.（2） apply varied-frequency ofalternating current to synthesis of nanowires is a new mathod, which provides thetheoretical basis for the effective control of alloy nanowire growth.（3） analyse thephase structure change and growth rule of nanowires.

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