催化学报 ›› 2017, Vol. 38 ›› Issue (2): 305-312.DOI: 10.1016/S1872-2067(16)62560-3

• 论文 • 上一篇    下一篇

CeO2修饰的Pt/Ni催化剂在碱性溶液中对乙醇电催化氧化性能的增强

徐志花a,b, 饶丽霞b, 宋海燕b, 严朝雄a,b, 张利君b, 杨水彬b   

  1. a 江汉大学光电化学材料与器件教育部重点实验室及柔性显示材料与技术湖北省协同创新中心, 湖北武汉 430056;
    b 黄冈师范学院催化材料制备及应用湖北省重点实验室, 湖北黄冈 438000
  • 收稿日期:2016-08-29 修回日期:2016-09-22 出版日期:2017-02-18 发布日期:2017-03-14
  • 通讯作者: Zhaoxiong Yan,Tel:+86-13720263625;E-mail:zhaoxiongyan75@163.com;Shuibin Yang,Tel:+86-13409708829;E-mail:yangshuibin@hgnu.edu.cn
  • 基金资助:

    国家自然科学基金(21307038,21577046);教育部重点项目(212115);黄冈师范学院物理化学实验改革项目(2015CK12).

Enhanced ethanol electro-oxidation on CeO2-modified Pt/Ni catalysts in alkaline solution

Zhihua Xua,b, Lixia Raob, Haiyan Songb, Zhaoxiong Yana,b, Lijun Zhangb, Shuibin Yangb   

  1. a Key Laboratory of Optoelectronic Chemical Materials and Devices of Ministry of Education, and Flexible Display Materials and Technology Co-innovation Center of Hubei Province, Jianghan University, Wuhan 430056, Hubei, China;
    b Hubei Key Laboratory for Processing and Application of Catalytic Materials, Huanggang Normal University, Huanggang 438000, Hubei, China
  • Received:2016-08-29 Revised:2016-09-22 Online:2017-02-18 Published:2017-03-14
  • Contact: 10.1016/S1872-2067(16)62560-3
  • Supported by:

    This work was supported by the National Natural Science Foundation of China (21307038 and 21577046), Key Project of Chinese Ministry of Education (212115), and Physical Chemistry Experiment of Huanggang Normal University (2015CK12).

摘要:

有机小分子直接燃料电池具有高能量密度和转换效率、易贮存及运输方便等优点.在过去几十年,有机小分子化合物尤其是乙醇的电催化氧化引起了研究者的关注,高活性和稳定性及低价格的电催化剂的设计和制备一直是乙醇燃料电池的研究热点.本文采用复合电沉积方法制备了Ni和CeO2复合镀层,然后利用Ni置换铂前驱体中Pt的方法制备了纳米CeO2修饰的Pt/Ni电催化剂(Pt/Ni-CeO2).采用X射线衍射(XRD)、扫描电子显微镜(SEM)及能谱仪(EDS)等手段表征了所制样品的组成和相结构、表面形貌及组成成份.
XRD结果表明,所制Pt/Ni催化剂主要是PtNi合金相结构.与Pt/Ni相比,Pt/Ni-CeO2催化剂的XRD峰强明显变弱,表明纳米CeO2修饰的Pt/Ni电催化剂的结晶性较差或者其晶体颗粒较小.这可能是由于CeO2的共沉积阻止了Ni纳米颗粒的进一步生长或团聚.当电镀液中CeO2含量为50和100 mg/L时,所制Pt/Ni-CeO2催化剂样品Pt/NiCe1和Pt/NiCe2的XRD谱上未观察到CeO2相关的衍射峰,这主要可归因于催化剂中沉积的CeO2量少或其高度分散.随着电镀液中CeO2浓度进一步增大到200 mg/L时,在Pt/Ni-CeO2催化剂(Pt/NiCe4)的XRD谱上出现了CeO2相关的衍射峰.这表明采用复合电沉积-化学还原法可以成功制备CeO2修饰的Pt/Ni电催化剂.SEM结果显示,所制催化剂都是由团聚状态的纳米颗粒组成,并且Pt/NiCe2表现出比Pt/Ni更开放的微结构,从而有利于反应物扩散至催化剂内部.该结果进一步表明共沉积的CeO2对所制Pt/Ni催化剂微结构的影响.此外,EDS结果也证实成功制备了CeO2修饰的Pt/Ni电催化剂.
采用多次循环伏安、电流时间曲线和电化学阻抗谱(EIS)等手段研究了所制电催化剂的电化学性能.与Pt/Ni相比,Pt/Ni-CeO2催化剂表现出更好的电催化氧化乙醇活性和稳定性,这可能与CeO2的贮氧特性及其共沉积增大了电极的粗糙度有关.红外光谱测试结果表明,在CeO2修饰的Pt/Ni电催化剂催化氧化乙醇过程中,CH3COO-可能是乙醇氧化的主要产物.在所制催化剂中,CeO2含量影响其电催化氧化乙醇性能.循环伏安和电流时间曲线测试结果表明,随着催化剂中CeO2含量增大,催化剂活性先增加后减弱.电化学阻抗谱结果表明,随着CeO2含量增大,CeO2修饰的Pt/Ni电催化剂的接触电阻先增大后变小再变大;而电荷转移电阻不断变小.在电解液中含有100 mg/L CeO2时所制电催化剂(Pt/NiCe2)具有最佳的电催化氧化乙醇活性和稳定性.这主要与CeO2的贮氧功能、Pt与CeO2/Ni间的相互作用和其较小的接触电阻和电荷转移电阻有关.该结果可为设计和制备低价格、高活性乙醇燃料电池中的催化剂提供思路.

关键词: 直接乙醇燃料电池, 乙醇氧化, 纳米二氧化铈, 复合电沉积, 电催化剂

Abstract:

Pt/Ni catalysts modified with CeO2 nanoparticles were prepared by simple composite electrodeposition of Ni and CeO2, and spontaneous Ni partial replacement by Pt processes. The as-prepared CeO2-modified Pt/Ni catalysts showed enhanced catalytic performance for ethanol electro-oxidation compared with pure Pt/Ni, and acetate species were proposed to be the main products of the oxidation when using these catalysts. The content of CeO2 in the as-prepared catalysts influenced their catalytic activity, with Pt/NiCe2 (obtained from an electrolyte containing 100 mg/L CeO2 nanoparticles) exhibiting higher activity and relatively better stability in ethanol electro-oxidation. This was mainly due to the oxygen storage capacity of CeO2, the interaction between Pt and CeO2/Ni, and the relatively small contact and charge transfer resistances. The results of this work thus suggest that electrocatalysts with low price and high activity can be rationally designed and produced by a simple route for use in direct ethanol fuel cells.

Key words: Direct ethanol fuel cell, Ethanol oxidation, CeO2 nanoparticle, Composite electrodeposition, Electrocatalyst