| 高活性甲醇氧化电催化剂Pt-Pd纳米合金的组分可控合成 |
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| 引用本文： | 赵海强,齐卫宏,周鑫峰,吴灏斐,李业军.高活性甲醇氧化电催化剂Pt-Pd纳米合金的组分可控合成[J].催化学报,2018,39(2):342-349. |
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| 作者姓名： | 赵海强 齐卫宏 周鑫峰 吴灏斐 李业军 |
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| 作者单位： | 中南大学材料科学与工程学院,湖南长沙,410083
中南大学材料科学与工程学院,湖南长沙410083;中南大学教育部有色金属材料科学与工程重点实验室,湖南长沙410083
中南大学物理与电子学院先进材料超微结构与超快过程研究重点实验室,湖南长沙,410083 |
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| 基金项目： | 国家自然科学基金，This work was supported by the National Natural Science Foundation of China |
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| 摘 要： | Pt纳米粒子由于其本身独特的物理、化学性质以及能够同时促进氧化和还原反应,在工业生产和商业设备中(尤其在直接甲醇燃料电池中)广泛用作重要的电催化剂.然而,Pt作为贵金属在自然界中的含量极其稀少,价格昂贵;另外,甲醇氧化反应中产生的中间产物CO很容易市Pt纳米粒子中毒而失活.因此,迫切需要一种Pt用量少,催化性能高的材料.一制备高活性比表面积的Pt纳米颗粒,可以有效提高Pt利用率.另外,调控纳米粒子使其裸露特定的晶面、边、角以及缺陷也能有效提升催化性能.还可以采用Pt纳米粒子结合其它金属元素形成双金属合金,如,Pt-M (M = Pd,Au,Ag,Ru,Fe,Co,Ni,等)催化剂,可以在减少Pt元素用量的同时有效提升催化活性.在众多可供选择的元素中,Pd相对于Pt价格低廉,但两者具有相近的物理、化学性质以及较高的电催化性能,使Pt-Pd纳米合金呈现十分优异的电催化性能.研究表明,Pt-Pd纳米合金在酸性和CO环境中能有效催化有机小分子电氧化过程.另外,在酸性环境中,用Pd替代Cu,Ag,Co或Ni,可以有效减少催化剂的腐蚀.本文在乙二醇溶液中同时还原K2PtCl4和Na2PdCl4,在110 ℃C反应5 h制备出超细的Pt-Pd纳米合金.通过X射线衍射(XRD)、透射电子显微镜(TEM)、高分辨透射电子显微镜(HRTEM)以及能谱仪(EDS)对合金进行表征,从而确定产物为尺寸4 nm左右的Pt-Pd纳米合金,且通过改变金属前驱体的投料比可以有效调控Pt-Pd合金组分(按元素比例分别表示为Pt1Pd3,Pt1Pd1,Pt3Pd1).采用循环伏安法、线性扫描伏安法以及计时安培法等多种手段测试样品在0.5 mol/L H2SO4和0.5 mol/L CH3OH的酸性环境中(50 mV/s)电化学性能,并与商业Pt/C进行比较.结果表明,合金的催化性能和组分密切相关,当Pt元素的含量为75%左右时,Pt-Pd纳米合金表现出最佳的催化活性和稳定性,其中Pt3Pd1的电催化质量活性可达商业Pt/C的7倍之多.我们把Pt-Pd纳米合金的催化性能对其组分的依赖性归结为甲醇氧化反应中的双官能团机制,反应中,Pt可有效催化甲醇脱氢产生Pt-CO,Pd则催化水脱氢形成Pd-OH.当Pd含量减少时,Pt表面的水脱氢反应只有在高电位才能发生,从而降低催化效率;而Pd含量过多,则会抑制Pt催化甲醇的脱氢反应,使催化效率大大降低.因此,只有适宜Pt/Pd比例,才能有效提升催化效率.
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| 关 键 词： | 铂钯纳米合金 组分和尺寸可控 甲醇氧化 Platinum and palladium alloy nanoparticles Composition and size control Methanol oxidation |
| 收稿时间： | 20 September 2017 |
Composition-controlled synthesis of platinum and palladium nanoalloys as highly active electrocatalysts for methanol oxidation |
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| Haiqiang Zhao,Weihong Qi,Xinfeng Zhou,Haofei Wu,Yejun Li.Composition-controlled synthesis of platinum and palladium nanoalloys as highly active electrocatalysts for methanol oxidation[J].Chinese Journal of Catalysis,2018,39(2):342-349. |
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| Authors: | Haiqiang Zhao Weihong Qi Xinfeng Zhou Haofei Wu Yejun Li |
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| Institution: | 1. School of Materials Science and Engineering, Central South University, Changsha 410083, Hunan, China;2. Key Laboratory of Non-ferrous Materials Science and Engineering, Ministry of Education, Central South University, Changsha 410083, Hunan, China;3. Hunan Key Laboratory of Super Microstructure and Ultrafast Process, School of Physics and Electronics, Central South University, Changsha 410083, Hunan, China |
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| Abstract: | Platinum and palladium (PtPd) alloy nanoparticles (NPs) are excellent catalysts for direct methanol fuel cells. In this study, we developed PtPd alloy NPs through the co-reduction of K2PtCl4and Na2PdCl4in a polyol synthesis environment. During the reaction, the feed molar ratio of the two precursors was carried over to the final products, which have a narrow size distribution with a mean size of approximately 4 nm. The catalytic activity for methanol oxidation reactions possible depends closely on the composition of as-prepared PtPd alloy NPs, and the NPs with a Pt atomic percentage of approximately 75% result in higher activity and stability with a mass specific activity that is 7 times greater than that of commercial Pt/C catalysts. The results indicate that through composition control, PtPd alloy NPs can improve the effectiveness of catalytic performance. |
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| Keywords: | Platinum and palladium alloy nanoparticles Composition and size control Methanol oxidation |
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