pH值对微波乙二醇法制备Pd/C催化剂性能影响
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摘要
采用微波辅助乙二醇还原法在不同pH值条件下快速高效地制备了Pd/C催化剂,并分别采用X射线衍射光谱法(XRD)和透射电子显微镜法(TEM)技术表征样品的晶体结构和颗粒形貌,采用循环伏安法(CV)测试Pd/C催化剂电催化氧化甲酸的性能。XRD结果表明制得的催化剂均为Pd面心立方结构,随着还原pH值的增高,样品的相对结晶度降低,平均粒径减小。TEM结果表明,当NaOH加入量为0.7 mL、pH=10.2时,催化剂的平均粒径为(3.0±0.7)nm,颗粒粒径分散性较好,也表现出最好的电催化性能。从CV曲线可见,随着pH的增高制得的Pd/C催化剂电催化氧化的性能先提高后降低,Pd/C-10.2氧化峰电位下Pd的质量比活性达到1 590 mA/mg,分别是Pd/C-9.0和Pd/C-12.1的3倍和2.5倍。
Pd/C catalysts were prepared by microwave assisted ethylene glycol reduction method under the conditions of different pH values. XRD and TEM were used to characterize the crystal structure and particle morphology of catalysts, respectively. And the performance of electrocatalytic oxidation of formic acid of the Pd/C catalyst was characterized by CV. XRD results show that all prepared catalysts display the typical character of Pd face center cubic phase and the relative crystalline and average particle diameter decrease with increasing reduction pH value.TEM results show that the catalyst average particle size is(3.0±0.7) nm with good dispersion when the pH value is10.2 with the addition of 0.7 mL NaOH. And the catalyst prepared under such a condition also obtaines the best electrocatalytic performance. The CV curves show the electrocatalytic oxidation performance of prepared Pd/C catalyst starts to evaluate, then decrease, and the Pd catalytic activity of Pd/C-10.2 oxidation peak potential is1 590 mA/mg, which is about respectively as much 3 times and 2.5 times as that of Pd/C-9.0 and Pd/C-12.1.
Pd/C catalysts were prepared by microwave assisted ethylene glycol reduction method under the conditions of different pH values. XRD and TEM were used to characterize the crystal structure and particle morphology of catalysts, respectively. And the performance of electrocatalytic oxidation of formic acid of the Pd/C catalyst was characterized by CV. XRD results show that all prepared catalysts display the typical character of Pd face center cubic phase and the relative crystalline and average particle diameter decrease with increasing reduction pH value.TEM results show that the catalyst average particle size is(3.0±0.7) nm with good dispersion when the pH value is10.2 with the addition of 0.7 mL NaOH. And the catalyst prepared under such a condition also obtaines the best electrocatalytic performance. The CV curves show the electrocatalytic oxidation performance of prepared Pd/C catalyst starts to evaluate, then decrease, and the Pd catalytic activity of Pd/C-10.2 oxidation peak potential is1 590 mA/mg, which is about respectively as much 3 times and 2.5 times as that of Pd/C-9.0 and Pd/C-12.1.
引文
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[2]YIN S.Functionalizing carbon nanotubes for effective electrocatalysts supports by an intermittent microwave heating method[J].Journal of Power Sources,2012,198:1-6.
[3]RICE C.Catalysts for direct formic acid fuel cells[J].Journal of Power Sources,2003,115(2):229-235.
[4]QU W L.ZrC-C and ZrO2-C as novel supports of Pd catalysts for formic acid electrooxidation[J].Fuel Cells,2013,13(2):149-157.
[5]CHEN J.Studies on how to obtain the best catalytic activity of Pt/C catalyst by three reduction routes for methanol electro-oxidation[J].Electrochemistry Communications,2011,13(4):314-316.
[6]LIU Z.Nanostructured Pt/C and Pd/C catalysts for direct formic acid fuel cells[J].Journal of Power Sources,2006,161(2):831-835.
[7]LUO Y.Effect of Pd ions in electrolyte on electrocatalytic performance of carbon supported Pd catalyst for oxidation of formic acid[J].Electrochimica Acta,2013,87:839-843.
[8]CHEN W X,LEE J Y,LIU Z.Preparation of Pt and PtRu nanoparticles supported on carbon nanotubes by microwave-assisted heating polyol process[J].Materials Letters,2004,58(25):3166-3169.
[9]YAWEN T.Preparation method of an ultrafine carbon supported Pd catalyst as an anodic catalyst in a direct formic acid fuel cell[J].Electrochemistry Communications,2006,8(10):1625-1627.
[10]LI X.Microwave polyol synthesis of Pt/CNTs catalysts:effects of pH on particle size and electrocatalytic activity for methanol electrooxidization[J].Carbon,2005,43(10):2168-2174.