• فهرس المقالات Platinum

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        1 - Study of nonlinear optical properties of platinum and gold nanoparticles under a CW laser irradiation at 532 nm
        Mina Eslamifar
        10.30495/jtap.162231
        This work presents a study on the thermo-optical properties of colloidal gold nanoparticles (AuNPs) and platinum nanoparticles (PtNPs) under a low power laser irradiation at 532 nm. Samples of gold and platinum are synthesized by nanosecond pulsed laser ablation of pure أکثر
        This work presents a study on the thermo-optical properties of colloidal gold nanoparticles (AuNPs) and platinum nanoparticles (PtNPs) under a low power laser irradiation at 532 nm. Samples of gold and platinum are synthesized by nanosecond pulsed laser ablation of pure gold and platinum plates in the distilled water. The formation of the AuNPs and PtNPs has been evidenced by optical absorption spectra and transmission electron microscopy. The thermo-optical properties of AuNPs and PtNPs are studied using Z-scan technique. The nonlinear optical measurments exhibit a very large nonlinear refraction close to the surface plasmon resonance frequency of the nanoparticles. Our results reveal that the diffusion in the colloids is due to nonlocal thermal process. This work suggests that thermal nonlinear refraction will play an important role in development of photonic application involving metal nanoparticles colloids تفاصيل المقالة
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        2 - Monte Carlo and QSAR Study on Biological Activity of Several Platinum (IV) Anti Cancer Drugs
        robabeh sayyadikordabadi Abdollah Fallah Shojaei Asghar Alizadehdakhel leila mohammadinargesi Ghasem Ghasemi
        10.30495/jptc.2021.20871
        QSAR investigations of some platinum (IV) derivatives were conducted using multiple linear regression (MLR) and artificial neural network (ANN) as modelling tools, along with simulated annealing (SA) and genetic algorithm (GA) optimization algorithms. In addition, CORAL أکثر
        QSAR investigations of some platinum (IV) derivatives were conducted using multiple linear regression (MLR) and artificial neural network (ANN) as modelling tools, along with simulated annealing (SA) and genetic algorithm (GA) optimization algorithms. In addition, CORAL software was used to correlate the biological activity to the structural parameters of the drugs. The obtained results from different approaches were compared and GA-ANN combination showed the best performance according to its correlation coefficient (R2) and mean sum square errors (RMSE). From the GA-ANN method, it was revealed that MTAS8e, ESpm05d, BElv3, MWC09, ESpm14u, BEHe2, RDF125e, and S3K are the most important descriptors. From Monte Carlo simulations, it was found that the presence of double bond, present of Platinum, number of chlorine connected to Pt, branching in molecular skeleton and presence of N and O atoms are the most important molecular features affecting the biological activity of the drug. It was concluded that simultaneous utilization of QSAR and Monte Carlo method can lead to a more comprehensive understanding of the relation between physico-chemical, structural or theoretical molecular descriptors of drugs to their biological activities. تفاصيل المقالة
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        3 - Electrocatalytic properties of platinum and it's binary alloy with vanadium in oxygen reduction reaction(ORR)
        Mohammad Yari Sajjad Sedaghat Sherehjini
        The electrocatalysis of the oxygen reduction reaction (ORR) on carbon supportedPt-V (1:1) catalyst in polymer electrolyte fuel cells (PEFC) was investigated. Atan oxygen pressure of one atm an enhanced electrocatalytic property of Pt-V/Ccompared with Pt/C is revealed. T أکثر
        The electrocatalysis of the oxygen reduction reaction (ORR) on carbon supportedPt-V (1:1) catalyst in polymer electrolyte fuel cells (PEFC) was investigated. Atan oxygen pressure of one atm an enhanced electrocatalytic property of Pt-V/Ccompared with Pt/C is revealed. These results indicate the occurrence of adifferent electrocatalytic mechanism for the ORR on Pt/C and Pt-V/C. Anincrease of mass transport overpotentials is observed for the Pt-V/C catalyst, andthis was related to the presence of vanadium oxide. So the ORR activity of Pt-V/Cat oxygen pressure of one atm is higher than that of Pt/C. تفاصيل المقالة
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        4 - CATALYTIC REFORMING OF n-HEPTANE ON PLATINUMNIOBIUM SUPPORTED ON GAMMA-ALUMINA
        Mehdi Vadi Gholamreza Farmani Hamidreza Seyedjafari M. Sohrabi
        The series of mono-metallic and bi-metallic catalysts have been prepared by impregnatingwith solutions containing compound of H2PtC15,NbC15 and lml HC1 (0.1 mol). The activityand selectivity of the catalysts have been determined under conditions at 450-500°C, 15-30a أکثر
        The series of mono-metallic and bi-metallic catalysts have been prepared by impregnatingwith solutions containing compound of H2PtC15,NbC15 and lml HC1 (0.1 mol). The activityand selectivity of the catalysts have been determined under conditions at 450-500°C, 15-30atm. Molar ratio H2/C7H16=5 and VVH=1.5/h for converting n-heptane. Under theseexperimental conditions it has been established that the conversion of n-heptane intobranched aliphatic isomers is catalyzed by a bifunctional mechanism. The results show thatwhen Nb is present, the catalysts are much more stable and have much higher selectivities forisomerization reaction. At a given conversion the bimetallic catalysts produce much lowerconcentrations of cracked products. It is shown that Nb modifies the acidity of the support,resulting to higher selectivity for isomerization and lower selectivity for cracking and alsomodifies the properties of the Pt. تفاصيل المقالة
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        5 - Catalytic Reforming of n-Heptane on Platimum - Rhenium Supported on Gamma-Alumina
        M. Vadi M. Bazargani N. Astaneh M. Alipour
        Catalyitic reforming is one of the refinery processes in catalyst conversion that results to anincreases in octane number of naphtan which leads to production of gasoline with higher octanenumber. Hydrocarbons with high octan number that are produced in reforming proces أکثر
        Catalyitic reforming is one of the refinery processes in catalyst conversion that results to anincreases in octane number of naphtan which leads to production of gasoline with higher octanenumber. Hydrocarbons with high octan number that are produced in reforming process are as;aromatics, paraffins, isomers and etc.Not only Aromatics are used as fuel for motors but they are also useful in petrochemical industry.Also hydrogen is produced as a subsidiary in the process. In this research, platinium-rhenium isused as a catalyst with the combination of "Re=0.4"and"Pt=0.3".the activity and selectivity of thecatalysts have been determined under condition at 350- 450oC and 30at. Pressure molar ratioH2/C7H16=5 and VVH=1.5 mL/h.Our results proved that this catalyst produces good products under 30 atmosphere pressure andtemperature ranges between 350 - 450oC but at higher temperatures such as 490 oC and over willgenerate lots of cracking and low quality black products that can not be analyzed bychromatography. This shows that in these temperatures the action of cracking is very much.However in temperature lower than 490 oC, the products have yellow color and this shows theexistence of aromatic compounds.In comparison between two catalysts with different percentages 0.3Pt=0.4Re catalyst has moreactivity. It also shows more selectivity in aromatization in comparison with 0.3Pt-0.3Re catalyst. تفاصيل المقالة
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        6 - CATALYTIC REFORMING OF n-HEPTANE ON PLATINUM-TUNGSTEN SUPPORTED ON GAMMA-ALUMINA
        M. Vadi A. Safavi A. Jamshidi
        The mono-metallic and bi-metallic catalysts have been prepared by impregnating with solutions containing a compound of H2PtCl6,WO3 and 1ml HCl (0.1 mol). It should be noted that the catalysts’ activity and selectivity have been determined under these conditions : أکثر
        The mono-metallic and bi-metallic catalysts have been prepared by impregnating with solutions containing a compound of H2PtCl6,WO3 and 1ml HCl (0.1 mol). It should be noted that the catalysts’ activity and selectivity have been determined under these conditions : 450-5000C ,and 15-25atm by H2. For converting n-heptane , the molar ratio H2/C7H16 is 5 , and LHSV is 1.5ml/h. It has been proved that , under these experimental conditions , the conversion of n-heptane into branched aliphatic isomers is catalyzed by a bifunctional mechanism. The results indicate that in the presence of W , the catalysts have much higher selectivity and stability for isomerization reaction. At a given conversion , the bi-metallic catalysts produce much lower concentrations of cracked products. According to the tests , W modifies the support acidity resulting to the higher selectivity for isomerization and the lower one for cracking , and it also modifies the Pt properties تفاصيل المقالة
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        7 - Separation and Recovery of Platinum by Magnetic Coreshell Nanostructures Modified with N-(2-aminoethyl)-3- aminopropyltrimethoxysilane
        Mansoor Anbia Ruholla Mehrizi
        In this paper, Fe3 O4 @SiO2 core/shell magnetic nanostructure has been synthesized and modified by N-(2-aminoethyl)-3-aminopropyltrimethoxysilane (AEAPTMS). Fe3 O4 @SiO2 was used as a novel adsorbent for separation of hexachloroplatinic acid. X-ray diffraction (XRD), sc أکثر
        In this paper, Fe3 O4 @SiO2 core/shell magnetic nanostructure has been synthesized and modified by N-(2-aminoethyl)-3-aminopropyltrimethoxysilane (AEAPTMS). Fe3 O4 @SiO2 was used as a novel adsorbent for separation of hexachloroplatinic acid. X-ray diffraction (XRD), scanning electron microscopy (SEM), and FT-IR technique were used to characterize morphologies and surface texturing of these adsorbents. The effective factors on adsorption, such as pH, contact time; salt effect and temperature were studied systematically. The optimal conditions of Platinum adsorption were obtained at temperature of about 25o C, pH about 2.5 and the equilibrium time of 30-40 minutes. The maximum adsorption capacity (qmax) in the optimal conditions was equal to 74 mg/g. The magnetic separation of the absorbent was achieved by a magnet and finally the absorbent was compared with other absorbents. Inductive coupled plasma optical emission spectrometer (ICP-OES) was used for determination of metal ion concentrations in the aqueous solution. تفاصيل المقالة
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        8 - Separation and Recovery of Platinum by Magnetic Core-shell Nano-structures Modified with N-(2-aminoethyl)-3-aminopropyltrimethoxysilane
        Mansoor Anbia Ruholla Mehrizi
        In this paper, Fe 3 O 4 @SiO 2 core/shell magnetic nanostructure has been synthesized and modified by N-(2-aminoethyl)-3-aminopropyltrimethoxysilane (AEAPTMS). Fe 3 O 4 @SiO 2 was used as a novel adsorbent for separation of hexachloroplatinic acid.X-ray dif أکثر
        In this paper, Fe 3 O 4 @SiO 2 core/shell magnetic nanostructure has been synthesized and modified by N-(2-aminoethyl)-3-aminopropyltrimethoxysilane (AEAPTMS). Fe 3 O 4 @SiO 2 was used as a novel adsorbent for separation of hexachloroplatinic acid.X-ray diffraction (XRD), scanning electron microscopy (SEM), and FT-IR technique were used to characterize morphologies and surface texturing of this adsorbents. The effective factors on adsorption, such as pH, contact time; salt effect and temperature were studied systematically. The optimal conditions of Platinum adsorption were obtained at temperature of about 25oC, pH about 2.5 and the equilibrium time of 30-40 minutes. The maximum adsorption capacity (qmax) in the optimal conditions was equal to 74mg/g. The magnetic separation of the absorbent was achieved by a magnet and finally the absorbent was compared with other absorbents. Inductive coupled plasma optical emission spectrometer (ICP-OES) was used for determination of metal ion concentrations in the aqueous solution تفاصيل المقالة
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        9 - On-line Pre-Concentration and Separation of Inorganic Arsenic Based on Nano Platinum-Multiwall Carbon Nanotubes
        Hamid Shirkhanloo Ali Akbar Miran Beigi Amir Vahid Nasrin Shirkhanloo Behzad Kalantri Hossein Ali Ghadirian
        10.22034/jna.2014.02.001
        On-line solid phase extraction (SPE) based on nano adsorbent for pre-concentration of inorganic arsenic in water and waste water samples was developed prior to determine by hydride generation atomic absorption spectrometry (HG-AAS). By hydride generation simulation syst أکثر
        On-line solid phase extraction (SPE) based on nano adsorbent for pre-concentration of inorganic arsenic in water and waste water samples was developed prior to determine by hydride generation atomic absorption spectrometry (HG-AAS). By hydride generation simulation system (HGSS), the inorganic arsenic in liquid samples changed to hydride form and pass through nano platinum multi wall carbon nanotube (3 wt % Pt, NPt-MWCNT,). The hydride form of arsenic (AsH3), pre-concentrated on NPt-MWCNTs and then completely desorption by electric heater accessory at 200oC for determining. The detection limit (LOD) and linear range of perposed method were obtained 0.4 ng L-1 and 6 –410 ng L-1 respectively(R2 = 0.9988). The relative standard deviations (%RSD) at 100 ng L-1 of analyte were found less than 5%. The capacity and efficiency of nano adsorbent were 75 mg g-1 and 96% at argon flow rate less than 100 ml min-1. The developed method was applied successfully to determination of ultra trace of inorganic arsenic in environmental samples by HG-AAS. تفاصيل المقالة
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        10 - Introducing Pt/ZnO as a new non carbon substrate electro catalyst for oxygen reduction reaction at low temperature acidic fuel cells
        Rasol Abdullah Mirzaie Fatemeh Hamedi
        Gas diffusion electrode was used for providing better conditions in fuel cell systems for oxygen reduction reaction (ORR). Because the slow kinetics of the oxygen reduction reaction at the proton exchange membrane fuel cell cathode restricts fuel cell efficiency. To thi أکثر
        Gas diffusion electrode was used for providing better conditions in fuel cell systems for oxygen reduction reaction (ORR). Because the slow kinetics of the oxygen reduction reaction at the proton exchange membrane fuel cell cathode restricts fuel cell efficiency. To this end, researchers have used platinum-coated carbon. In the present study, due to the reduction of carbon corrosion, Zinc oxide nanoparticles have been employed as a support material for platinum. The Pt/ZnO nanoparticles catalyst was made via a combined process of impregnation and seeding method. The microstructure of coating was characterized using scanning electron microscopy (SEM) which indicates that Pt nanoparticles are uniformly dispersed on the surface of ZnO. In order to investigate the chemical composition and crystalline phases of coating, X-ray analysis was carried out. Electrochemical Impedance Spectroscopy (EIS) was carried out for comparing the charge transfer effect during the ORR. The catalytic performance of the electrodes for ORR is evaluated through linear sweep voltammetry measurement. The O2 reduction current for Pt/ZnO alone is expectedly low due to the low electronic conductivity in ZnO. However, adding single-wall carbon nanotube (SWCNT) to the reaction layer improves the electrode performance. The prepared Pt/ZnO/SWCNT 30 wt. % electrode shows high catalytic activity for the ORR, which is probably attributed to conductivity changes caused by the addition of SWCNT. The electrochemical active surface area (ECSA) and durability investigation was studied by cyclic voltammetry in nitrogen saturated 0.5 M H2SO4. The results calculated from ECSA measurements were indicated that the degradation rate of optimized electrode is smaller than Pt/C electrode. تفاصيل المقالة
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        11 - A Nickel Sublayer: An Improvement in the Electrochemical Performance of Platinum-Based Electrocatalysts as Anodes in Glucose Alkaline Fuel Cells
        Behnam Moeini Masoumeh Ghalkhani Tahereh G. Avval Matthew R. Linford Rasol Abdullah Mirzaie
        Platinum–nickel electrocatalysts supported on the modified carbon paper (MCP) were prepared by electrodeposition. Here, various procedures were applied for the electrodeposition of nickel and platinum particles, separately or simultaneously, on the surface of the أکثر
        Platinum–nickel electrocatalysts supported on the modified carbon paper (MCP) were prepared by electrodeposition. Here, various procedures were applied for the electrodeposition of nickel and platinum particles, separately or simultaneously, on the surface of the MCP as an anode electrode for glucose alkaline fuel cells. The establishment of the best procedure for this fabrication is the main goal of this work. The obtained electrocatalysts were characterized by cyclic voltammetry, linear sweep voltammetry, electrochemical impedance spectroscopy (EIS), scanning electron microscopy (SEM), and X-ray photoelectron spectroscopy (XPS). The results showed that the Pt/Ni electrocatalyst, electrodeposited from two separate solutions containing Ni and then Pt ions, has excellent electrocatalytic activity for the glucose oxidation reaction (GOR). On the other hand, the Pt/Ni/MCP electrode showed satisfactory repeatability when subjected to continuous cycling and less concentration polarization in the oxidation region of GOR (from -1 to 0.6 V vs. SCE). Also, the Pt/Ni/MCP electrode showed a significant increase in the exchange current density (0.95 mA cm-2) that accelerates the kinetics of the glucose oxidation reaction.These results indicate that modification of the catalyst layer structure in the present work is the most promising approach to achieve low-cost and efficient catalysts for use in glucose alkaline fuel cells. تفاصيل المقالة
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        12 - Applications of SEM-EDAX method in study of Baba-Ali & Galali iron ore, west of Hamedan
        Godratollah Rostami Paydar Mohammad Lotfi Majid Ghaderi Mansor Vossoughi-Abedini Azadeh Amiri
        Baba-Ali and Galali iron deposits are located west of Hamadan, within the Sanandaj-Sirjan geo-structural zone. Mineralogy and crystal-chemistry of the ore bodies using 57 analyses on the magnetite iron ore by SEM-EDAX method lead to some interesting results. Detecting t أکثر
        Baba-Ali and Galali iron deposits are located west of Hamadan, within the Sanandaj-Sirjan geo-structural zone. Mineralogy and crystal-chemistry of the ore bodies using 57 analyses on the magnetite iron ore by SEM-EDAX method lead to some interesting results. Detecting the concentration of some trace elements such as V, Co, Ni, Cu, Cr, Ti, Au, PGE (Platinum Group Elements) and some impurities of S and P in the ore bodies indicates that only primary pyrites have concentrations of Pt. Other generations of pyrite and magnetite are depleted in these trace elements. The late stage of hydrothermal fluids that leads to mineralization of pyrite in calcite-quartz veins is important for Au mineralization and therefore pyrite is the best carrier for Au. Detection of abundant phlogopite crystals and trace element concentration patterns in the Galali iron ore has strengthened the acceptance of volcanogenic magnesium skarn type hypothesis. تفاصيل المقالة
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        13 - فعالیت الکتروکاتالیستی نانوکاتالیست Pt/C پایدارشده با مقدارهای متفاوت سدیم سیترات در واکنش کاهش اکسیژن
        کلثوم محرابی نژاد مهدی خیرمند
        10.30495/jacr.2023.1978750.2093
        در پژوهش حاضر، به منظور دستیابی به کارایی بیشتر و استفاده کمتر از الکتروکاتالیست پلاتین برای واکنش کاهش اکسیژن در کاتد پیل سوختی، فعالیت الکتروکاتالیستی نانوذره ها با 20 درصدوزنی پلاتین بر کربن (Pt(20wt%)/C) با نسبت‌های متفاوت، ماده پایدارکننده تری سدیم سیترات برای واکن أکثر
        در پژوهش حاضر، به منظور دستیابی به کارایی بیشتر و استفاده کمتر از الکتروکاتالیست پلاتین برای واکنش کاهش اکسیژن در کاتد پیل سوختی، فعالیت الکتروکاتالیستی نانوذره ها با 20 درصدوزنی پلاتین بر کربن (Pt(20wt%)/C) با نسبت‌های متفاوت، ماده پایدارکننده تری سدیم سیترات برای واکنش کاهش اکسیژن سنتز شد. نسبت‌های 1:12، 1:9 ،1:6 ،1:3 از پلاتین و تری سدیم سیترات (Pt/C:TC) به عنوان عامل پایدارکننده با روش اشباع-کاهش آماده شد. میکروسکوپ الکترونی روبشی SEM برای ریخت شناسی نانوکاتالیست و روش های ولت آمپرسنجی چرخه‌ای(CV)، ولت آمپرسنجی با روبش خطی پتانسیل (LSV)، الکترود دیسک چرخان (RDE) و طیف سنجی رهبندی الکتروشیمایی (EIS) برای ارزیابی واکنش کاهش اکسیژن در لایه کاتالیست کاتد در محیط اسیدی به کارگرفته شدند. نتیجه ها نشان داد که کارایی الکتروکاتالیست ساخته شده بانسبت Pt/C:TC برابر با 1:3 برای کاهش اکسیژن نسبت به سایر الکترودها بهتر است. همچنین، مقاومت انتقال بار کمتر، توزیع مناسب‌تر و سطح فعال الکتروشیمیایی (m2gpt 1/7) بهتری دارند. افزون براین، تعداد الکترون های واکنش کاهش اکسیژن نیز محاسبه شد که برای نسبت 1:3 از مسیر چهار الکترونی پیروی ‌کرد. تفاصيل المقالة
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        14 - تهیه چندسازه نانولوله‌های کربنی/ پلاتین بلک و کاربرد آن برای الکتروکاتالیست واکنش آزادسازی هیدروژن
        ابراهیم شجاعی شهلا فتحی فرشته چکین
        در این پژوهش، ابتدا چندسازه نانولوله‌های کربنی/ پلاتین بلک با روش ساده، مؤثر و ارزان تهیه شد. نمونه تهیه شده با روش‌های میکروسکوپی الکترونی عبوری (TEM) و پراش انرژی پرتو ایکس (EDX) مورد بررسی قرار گرفت. تصاویر TEM نشان داد که نانوذره‌های پلاتین به‌صورت دانه‌های تسبیح رو أکثر
        در این پژوهش، ابتدا چندسازه نانولوله‌های کربنی/ پلاتین بلک با روش ساده، مؤثر و ارزان تهیه شد. نمونه تهیه شده با روش‌های میکروسکوپی الکترونی عبوری (TEM) و پراش انرژی پرتو ایکس (EDX) مورد بررسی قرار گرفت. تصاویر TEM نشان داد که نانوذره‌های پلاتین به‌صورت دانه‌های تسبیح روی دیواره خارجی نانولوله‌های کربنی تثبیت شده و وجود عنصر پلاتین (Pt) در طیف EDX دلیل بر حضور Pt در چندسازه است. سپس، با ساخت الکترود خمیر کربن اصلاح شده (CPE) با این نانو چندسازه، فعالیت کاتالیستی نانو چندسازه تهیه شده در محیط اسیدی به‌وسیله روش‌های الکتروشیمی از قبیل ولتامتری روبش خطی در واکنش آزادسازی هیدروژن مورد بررسی قرار گرفت. نتایج ولتامتری روبش خطی نشان داد که الکترود CPE اصلاح شده با Pt-CNT نسبت به الکترود CPE، با چگالی جریان بالاتر و پتانسیل کم منفی‌تر در واکنش آزادسازی هیدروژن ظاهر می‌شود. اثر عامل‌های متفاوت مانند نوع و غلظت الکترولیت و نسبت پلاتین بلک به نانولوله‌های کربنی در الکتروکاتالیست واکنش آزادسازی هیدروژن مورد بررسی قرار گرفت. نتایج نشان داد که سولفوریک اسید M 1/0 و نسبت 2:5 از پلاتین بلک به نانولوله‌های کربنی به‌عنوان شرایط بهینه در واکنش آزادسازی هیدروژن است. تثبیت چنین نانو چندسازه‌ای روی الکترود، موجب پتانسیل شروع فرایند آزادسازی هیدروژن حدود V2/0- و کمترین شیب تافل V-1 dec-14 شد. ضریب انتقال الکترون و چگالی مبادله جریان برای Pt-CNT/CPE با استفاده از شیب نمودار تافل به ترتیب حدود 3/1 وmA cm-2 12/0 برای واکنش آزادسازی هیدروژن به‌دست آمده است. تفاصيل المقالة
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        15 - The influence of alumina used as a support on the catalytic properties of Pt/Sn/Al2O3 systems in the dehydrogenation of isobutane
        Sedigheh Vaezifar hossein Faghihian Mehdi kamali
        In this research different types of Al2O3 were used as supports to prepare catalysts for dehydrogenation of isobutane to isobutene. These supports were Al2O3 from Merck, Axen and gamma Al2O3 synthesized from Al(OH)3. Sn/Pt/Al2O3 catalysts were prepared by sequential imp أکثر
        In this research different types of Al2O3 were used as supports to prepare catalysts for dehydrogenation of isobutane to isobutene. These supports were Al2O3 from Merck, Axen and gamma Al2O3 synthesized from Al(OH)3. Sn/Pt/Al2O3 catalysts were prepared by sequential impregnation, at first Pt and then Sn was deposited. Characterization of catalysts was performed by X-ray powder diffraction (XRD) and thermal analysis (TG/DTG) techniques. Elemental analysis of the catalysts was also carried out by wet chemical analysis using inductively coupled plasma (ICP) technique. Isobutane dehydrogenation was studied in a reactor under atmospheric pressure at 848 K. The conversion, selectivity and yield of the prepared catalysts were calculated. تفاصيل المقالة
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        16 - بررسی فعالیت کاتالیستی نانوکامپوزیت پالادیم- نانولوله های کربنی جهت الکترواکسایش متانول در پیل های سوختی و مقایسه آن با کاتالیست پلاتینی
        رقیه خالقیان مقدم
        در این تحقیق، نانوکامپوزیت پالادیم- نانولوله‌های کربنی- چیتوسان سنتز و با تکنیک های XRD و TEM شناسایی شد. نانوکامپوزیت سنتزشده برای اصلاح سطح الکترودهای کربن شیشه ای مورد استفاده واقع گردید. با استفاده از تکنیک‌ ولتامتری چرخه‌ای، فعالیت الکتروشیمیایی الکترود اصلاح‌شده ( أکثر
        در این تحقیق، نانوکامپوزیت پالادیم- نانولوله‌های کربنی- چیتوسان سنتز و با تکنیک های XRD و TEM شناسایی شد. نانوکامپوزیت سنتزشده برای اصلاح سطح الکترودهای کربن شیشه ای مورد استفاده واقع گردید. با استفاده از تکنیک‌ ولتامتری چرخه‌ای، فعالیت الکتروشیمیایی الکترود اصلاح‌شده (GC/MWCNTs-PdNPs-CH) برای الکترواکسایش متانول در محلول 5/0 مولار سدیم هیدروکسید و 0/1 مولار متانول مورد بررسی قرار گرفت. نتایج حاکی از آن بود که نانو کامپوزیت سنتز شده فعالیت بسیار بالایی جهت اکسایش متانول از خود نشان می دهد و از این رو، قابلیت استفاده به عنوان آند پیل های سوختی متانولی را داراست. اثر عوامل تجربی نظیر غلظت‌ های متانول و الکترولیت، محدوده پتانسیل و سرعت روبش پتانسیل بر دانسیته جریان آندی و پتانسیل اکسایش متانول نیز مورد بررسی واقع شد. همچنین در مقایسه فعالیت الکتروشیمیایی نانوکاتالیست پالادیم جهت اکسایش متانول با نوع پلاتینی مشخص گردید که نانوکاتالیست پالادیم، فعالیتی قابل ملاحظه و در حد کاتالیست حاوی نانوذرات پلاتین دارد و از این رو می تواند جایگزین بسیار مناسبی برای پلاتین در فرآیند الکترواکسایش متانول باشد. همچنین این جایگزینی، قیمت تمام شده کاتالیست را نیز کاهش می دهد. تفاصيل المقالة
      • حرية الوصول المقاله

        17 - تأثیر پلاتین بر رفتار خوردگی داغ نوع II پوشش‌های سیلیسیم-آلومیناید حاوی سیلیسیم زیر حد بحرانی
        سیدامیر آذرمهر کوروش شیروانی جوزدانی
        در این مقاله اثر اضافه شدن مقدار کم پلاتین به پوشش های سیلیسیم-آلومیناید دوغابی حاوی سیلیسیم کمتر از مقدار لازم برای ایجاد حفاظت کامل در این پوشش ها بررسی شده است. ضمن بررسی ریزساختار پوشش های حاصل، نقش پلاتین بر رفتار خوردگی داغ نوع II پوشش ها نیز مورد بحث قرار گرفته ا أکثر
        در این مقاله اثر اضافه شدن مقدار کم پلاتین به پوشش های سیلیسیم-آلومیناید دوغابی حاوی سیلیسیم کمتر از مقدار لازم برای ایجاد حفاظت کامل در این پوشش ها بررسی شده است. ضمن بررسی ریزساختار پوشش های حاصل، نقش پلاتین بر رفتار خوردگی داغ نوع II پوشش ها نیز مورد بحث قرار گرفته است. برای ایجاد پوشش های سیلیسیم و (پلاتین، سیلیسیم)-آلومیناید از روش سیلیکوآلومینایزنیگ دوغابی بر روی نمونه های از جنس سوپر آلیاژ پایه نیکل GTD-111 که قبلاً بر روی برخی از آنها لایه‌ای پلاتین با ضخامت 2 میکرومتر آبکاری شده بود، استفاده شد. مقدار سیلیسیم در دوغاب معادل 10 درصد وزنی نسبت به کل جامد دوغاب انتخاب شد تا مقدار سیلیسیم در پوشش حاصل کمتر از مقدار بحرانی لازم برای حفاظت کامل باشد. آزمون خوردگی داغ نوع II به روش کوره ای با استفاده رسوب نمکی با ترکیب Na2SO4-60mol%V2O5 در دمای 700 درجه سانتیگراد انجام شد. پس از 20 ساعت خوردگی داغ، اکسید محافظ Al2O3 و اکسید غیرمحافظ NiAl2O4 به ترتیب در پوشش های سیلیسیم-آلومیناید با و بدون پلاتین شناسایی شد. در عدم حضور پلاتین، فاز Ni3V2O8 نیز تشخیص داده شد که محصول انحلال NiO و NiAl2O4 در شرایط خوردگی داغ می باشد. در پایان 80 ساعت خوردگی داغ، برخلاف پوشش سیلسیم-آلومیناید، هنوز سیلیسیم در ساختار پوشش (پلاتین، سیلیسیم)-آلومیناید باقیمانده وجود داشت. تفاصيل المقالة

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