Acta Chim. Sinica ›› 2018, Vol. 76 ›› Issue (4): 292-297.DOI: 10.6023/A17110478 Previous Articles     Next Articles

Article

Au-Pt催化剂的控制合成及其对乙醇电氧化性能

吴匡衡a, 周亚威a, 马宪印b, 丁辰a, 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 上海电力学院环境与化学工程学院 上海市电力材料防护与新材料重点实验室 上海 200090
  • 收稿日期:2017-11-02 出版日期:2018-04-15 发布日期:2018-03-12
  • 通讯作者: 蔡文斌 E-mail:wbcai@fudan.edu.cn
  • 基金资助:

    国家自然科学基金(Nos.21473039,21733004),上海市国际科技合作基金(No.17520711200)和973计划(No.2015CB932303)资助项目.

Controlled Synthesis of Gold-Platinum Catalysts for Ethanol Electro-oxidation Reaction

Wu Kuanghenga, Zhou Yaweia, Ma Xianyinb, Ding Chena, Cai Wenbina   

  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;
    b Shanghai Key Laboratory of Materials Protection and Advanced Materials in Electric Power, College of Environmental and Chemical Engineering, Shanghai University of Electric Power, Shanghai 200090
  • Received:2017-11-02 Online:2018-04-15 Published:2018-03-12
  • Contact: 10.6023/A17110478 E-mail:wbcai@fudan.edu.cn
  • Supported by:

    Project supported by the National Natural Science Foundation of China (Nos. 21473039, 21733004), Science and Technology Commission of Shanghai Mu-nicipality (No. 17520711200) and 973 program (No. 2015CB932303).

Ethanol oxidation reaction (EOR) is a common anode process for direct ethanol fuel cell (DEFC) and ethanol reforming electrolyzer. Au@Pt and AuPt alloy are widely used bimetallic catalysts, yet no comparative study has been reported of electrocatalysis of EOR on these two differently structured catalysts. The present work aims to synthesize and characterize carbon supported Au@Pt and AuPt with controlled composition and size, and compare their electrocatalytic activities and stabilities toward EOR in alkaline media. For the synthesis of Au@Pt/C, a 5-nm Au colloid was first obtained by adding excessive amount of sodium borohydride to a chloroauric acid precursor containing sodium citrate with a mixed ice-water bath. CO gas was bubbled into the Au colloidal solution at 60℃ under strong stirring to reduce a desired amount of potassium tetrachloroplatinate(Ⅱ) to terminate Pt quasi-monolayer shell on Au nanoparticle core. A sonicated carbon black (Vulcan XC-72) aqueous slurry was then dropwise added to the above Au@Pt colloid, and the mixture was kept stirring for 48 h to ensure the exhaustive loading of Au@Pt nanoparticles onto the carbon support. For the synthesis of AuPt/C with the same Au:Pt molar ratio and metal loading as that for Au@Pt/C, coreduction of the Au(Ⅲ) and Pt(Ⅱ) species was attained by using sodium borohydride as the reducing agent with the rest procedures being same as the above mentioned. X-ray diffractometry (XRD) revealed that the diffraction peaks for Au@Pt/C were virtually same as those for Au/C, consistent with a Pt quasi-monolayer, while the diffraction peaks for AuPt/C located in between those for Au/C and Pt/C. X-ray photoelectron spectroscopy (XPS) results were consitent with the different structures of the two catalysts, and the Pt core level shift suggested an upshift of Pt d-band center for both bimetallic catalysts. Cyclic voltammetry and chronoamperometry revealed markedly increased EOR current on Au@Pt/C and AuPt/C, as compared to that of Pt/C and Au/C. CO-stripping voltammetry on Au@Pt/C and AuPt/C indicated that surface reconstruction occurred by potential cycling, resulting in a decrease of exposed Pt sites but not the electrocatalytic activities. 1H NMR analysis confirmed the C2 pathway is predominant. Nevertheless, Au@Pt/C outperformed AuPt/C and Pt/C with a lower onset oxidation potential and a higher peak current for EOR, as well as a slightly higher selectivity toward C1 pathway. Although the synergetic effect of Au-Pt bimetallic interface for EOR is not well understood, the enhanced adsorption of ethanol, OH, acetyl and CO on Pt sites may be accountable for the observed results.

Key words: ethanol oxidation reaction, electrocatalysis, AuPt bimetallic catalysts, core-shell structure, alloy structure