催化学报 ›› 2019, Vol. 40 ›› Issue (12): 1895-1903.DOI: 10.1016/S1872-2067(19)63338-3

• 论文 • 上一篇    下一篇

高效氧气还原催化剂Pt3Co/C的水相法新合成

黄金晶a, 丁辰a, 杨勇强b,c, 刘岗b,c, 蔡文斌a   

  1. a 复旦大学化学系, 能源材料化学协同创新中心, 上海市分子催化与功能材料表面重点实验室, 上海 200433;
    b 中国科学院金属研究所沈阳材料科学国家研究中心, 辽宁沈阳 110016;
    c 中国科学技术大学材料科学与工程学院, 安徽合肥 230026
  • 收稿日期:2019-01-02 修回日期:2019-02-28 出版日期:2019-12-18 发布日期:2019-09-21
  • 通讯作者: 蔡文斌
  • 基金资助:
    国家重点基础研究发展计划(2015CB932303);国家自然科学基金(21733004,21473039);上海市“科技创新行动计划”政府间国际科技合作项目(17520711200).

An alternate aqueous phase synthesis of the Pt3Co/C catalyst towards efficient oxygen reduction reaction

Jinjing Huanga, Chen Dinga, Yongqiang Yangb,c, Gang Liub,c, Wen-Bin Caia   

  1. a Shanghai Key Laboratory of Molecular Catalysis and Innovative Materials, Collaborative Innovation Center of Chemistry for Energy Materials, Department of Chemistry, Fudan University, Shanghai 200433, China;
    b Shenyang National Laboratory for Materials Science, Institute of Metal Research, Chinese Academy of Sciences, Shenyang 110016, Liaoning, China;
    c School of Materials Science and Engineering, University of Science and Technology of China, Hefei 230026, Anhui, China
  • Received:2019-01-02 Revised:2019-02-28 Online:2019-12-18 Published:2019-09-21
  • Supported by:
    This work was supported by the National Basic Research Program of China (973 Program, 2015CB932303), the National Natural Science Foundation of China (NSFC) (21733004 and 21473039), and the International Cooperation Program of Shanghai Science and Technology Committee (STCSM) (17520711200).

摘要: 碳载型Pt-Co合金催化剂是一种针对低温燃料电池最实用的阴极氧还原(ORR)催化剂,因此很有必要发展一种简易、环保的合成方法.目前碳载型Pt-Co合金催化剂的合成方法主要包括有机溶剂热法、多元醇还原法、反向微乳液法、浸渍还原法和水相法.其中,有机溶剂热法虽然能较好地实现含Pt双金属纳米合金催化剂的合成,但该方法所用的有机溶剂和封端剂会引起环境污染,同时Pt (acac)2和Co (acac)2前驱体成本较高.多元醇还原法采用乙二醇作为溶剂和还原剂,多元醇溶于水、较易去除是该方法的优点,但该法难以获得制定剂量比的PtCo合金,且后续需较高温度退火以提高合金度.反向微乳液法能较好地控制颗粒粒径,但金属纳米颗粒组成的均一性较难达成.同时,有机溶剂热法与反向微乳液法均面临去除有机物步骤繁琐且耗时长的问题.浸渍还原法需在H2气氛下高温煅烧含Pt和Co盐浸渍液的碳黑,虽可形成PtCo有序化合金结构,但易导致PtCo纳米颗粒的烧结,限制催化剂的质量比活性.水相合成法采用水作为前驱体和络合剂的唯一溶剂,并基于水溶性还原剂一锅法合成,无需强表面活性剂.虽然水相合成法是一种环境友好、成本低廉的合成方法,但其最大挑战是难以按投料金属比合成分散性良好、粒径较小及合金化程度高的PtCo纳米颗粒,因此需要进一步的发展.本研究首次报道了以一种非经典的二甲基胺硼烷(DMAB)还原剂为基础的水相一锅法合成碳载型PtCo催化剂(Pt含量约为20 wt.%)的方法.重点合成了具有最优原子比的Pt3Co/C-DMAB催化剂,并与采用NaBH4或N2H4·H2O合成的催化剂Pt3Co/C-NaBH4和Pt3Co/C-N2H4·H2O以及商业化催化剂Pt/C在结构和电催化性能方面进行了对比研究.结果表明,Pt3Co/C-DMAB在O2饱和的0.1mol L-1 HClO4溶液中表现出最好的电催化ORR性能,质量比活性与面积比活性分别是商业化Pt/C的4倍和6倍.Pt3Co/C-DMAB在含氧的0.1 mol/L HClO4溶液中,在0.60和1.05V(vs.RHE)区间经历了10000圈的电位扫描后,ORR半波电位仅降低了4mV,而商业化Pt/C催化剂在该条件下半波电位降低了24mV.Pt3Co/C-NaBH4和Pt3Co/C-N2H4·H2O虽然在面积比活性上与Pt3Co/C-DMAB相近,但前二者的质量比活性与商业化Pt/C的相近.ICP-AES、TEM、XRD和XPS等表征方法表明,除了PtCo合金有利的电子效应外,Pt3Co/C-DMAB上Pt3Co纳米粒子良好的分散性、较小的平均粒径(约3.4 ±0.4nm)和较高的合金度是该催化剂对ORR表现出色性能的成因.这种环保简便的水相合成法将为开发实用型ORR催化剂提供新途径.

关键词: 氧还原电催化剂, 铂钴合金, 水相合成, 二甲基胺硼烷, 结构与性能

Abstract: Carbon supported Pt-Co alloys are among the most promising electrocatalysts towards oxygen reduction reaction (ORR) for the application in low temperature fuel cells and beyond, thus their facile and green synthesis is highly demanded. Herein we initially report an alternate aqueous phase one-pot synthesis of such catalysts (containing nominally ca. 20 wt.% Pt) based on dimethylamine borane (DMAB) reduction. The as-obtained electrocatalyst (denoted as Pt3Co/C-DMAB) is compared with the ones obtained by NaBH4 and N2H4·H2O reduction (denoted as Pt3Co/C-NaBH4 and Pt3Co/C-N2H4·H2O, respectively) as well as a commercial Pt/C, in terms of the structure and electrocatalytic property. It turns out that Pt3Co/C-DMAB exhibits the highest ORR performance among all the tested samples in an O2-saturated 0.1 mol/L HClO4, with the mass activity (specific activity) ca. 4 (6) times as large as that for Pt/C. After 10000 cycles of the accelerated degradation test, the half-wave potential for ORR on Pt3Co/C-DMAB decreases only by 4 mV, in contrast to 24 mV for that on Pt/C. Pt3Co/C-NaBH4 or Pt3Co/C-N2H4·H2O shows a specific activity comparable to that for Pt3Co/C-DMAB, but a mass activity similar to that for Pt/C. ICP-AES, TEM, XRD and XPS characterizations indicate that Pt3Co nanoparticles are well-dispersed and alloyed with a mean particle size of ca. 3.4 ±0.4 nm, contributing to the prominent electrocatalytic performance of Pt3Co/C-DMAB. This simple aqueous synthetic route may provide an alternate opportunity for developing efficient practical electrocatalysts for ORR.

Key words: ORR electrocatalyst, Pt-Co alloy, Aqueous phase synthesis, Dimethylamine borane, Structure and property