Synthesis and evaluation of Pd-Sn/rGO catalyst for low ethanol concentrations electrooxidation
کد مقاله : 1045-CNF
نویسندگان
مرضیه غلامیان *1، محمد ژیانی2
1دانشگاه صنعتی اصفهان
2دانشکده شیمی، دانشگاه تربیت مدرس
چکیده مقاله
In recent years, fuel cell-based breath-alcohol analyzers (FCBrAA ) have received significant attention in comparison to different types of devices such as electrochemical oxidation [1]. The advantages of the FCBrAA are non-invasiveness, portability, high accuracy and rapid alcohol detection [2]. The high-performance direct alcohol fuel cell was expected to be a good substitute to serve in breath alcohol analyzers [3]. Low ethanol concentrations solutions are usually used for anode catalyst activity evaluation in breath alcohol analyzers. Over the past years, Palladium and Pd-M (M: Cu, Sn, Co, Ni,…) alloy have been widely used for alcohols oxidation especially in alkaline media [4]. M. Zhiani et al [5] were applied Pd-Cu/rGO as catalyst of ethanol oxidation sensor for FCBrAA in the concentration 5-50 mM. Herein, the electrocatalytic activates of Pd-Sn/rGO were evaluated for the low ethanol concentrations in the alkaline.
The amount of graphene oxide powder was dissolved in 20 ml ethylene glycol (EG) by ultrasonic technique for 1h. Then, the amount of PdCl2 and SnCl2 was dispersed in 5 ml EG and added to the GO dispersion; this was followed by stirring 12 h. The mixture was transferred to a flask equipped with a magnetic stirrer, under N2 atmosphere. Then 3 ml hydrazine hydrate which contained 0.25 g KOH was gradually added to the mixture. The mixture was stirred for 1 h at room temperature. After that, the black suspension was transferred to an autoclave (75 ml) and kept for 3 h at 200 °C. It was allowed to cool gradually at room temperature; the product was pulled out from the solution by centrifuging. It was washed several times with deionized water and ethanol. The prepared sample was dried in the oven at 45 °C overnight.
The EDS spectra was showed the existence of Pd and Sn elements. XRD patterns of Pd-Sn/rGO was displayed in the peak at 2θ = 22° (002) presented the reduced graphene oxide and the peaks at 2θ= 40.1, 46.6, 68.1, 82.1 and 86.6o corresponded to the crystallographic planes of (111), (200), (220), (311) and (222) in the cubic phase, respectively. The palladium peaks were shifted approximately to the size 2θ = 1o in Pd-Sn/rGO.
The electrocatalytic activities of Pd-Sn/rGO catalyst were evaluated using CV, LSV, Tafel slope and CHA, for the low ethanol concentrations (5-50 mM) in the alkaline media. Results of the cyclic voltammetry indicated that Pd-Sn/rGO has a specific activity in all concentrations. The obtained oxidation currents from cyclic voltammetry were increased monotonically as the ethanol concentration was raised. The EOR peak current density of Pd-Sn/rGO was approximately 144 mA mg_Pd^(-1) in 0.5 M KOH and 50 mM ethanol. LSV curves and Tafel plot of Pd-Sn/rGO have achieved -655 mV and 243 mV dec-1, respectively, in a solution containing 0.5 M KOH and 50 mM ethanol solution are shown. The CA results indicated stability of the catalyst.
Pd-Sn/rGO was synthesized using a simple and one-step method by chemical reduction agent. The activity evaluation of Pd-Sn/rGO as an anode catalyst for electrooxidation of low ethanol concentrations (5-50 mM) in order to use in fuel cell base breath alcohol analyzer.
کلیدواژه ها
Palladium-Tin (Pd-Sn), Reduced graphene oxide (rGO), Ethanol oxidation reaction (EOR), Alkaline
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