English

Modification of Tetrahexahedral Pd Nanocrystals with Ru and Their Performance for Methanol Electro-oxidation

• GUO Jincheng ,
• LIN Yanfen ,
• TIAN Na ^, ,
• SUN Shigang ^,

• State Key Laboratory of Physical Chemistry of Solid Surfaces, Department of Chemistry, College of Chemistry and Chemical Engineering, Xiamen University, Xiamen 361005, Fujian Province, P. R. China

Corresponding author: Email: tnsd@xmu.edu.cn (T.N.); Email: sgsun@xmu.edu.cn (S.S.)

• Received Date: 23 October 2018
  Accepted Date: 13 November 2018
  Revised Date: 12 November 2018
  Available Online: 15 July 2019
• Fund Project:

  The project was supported by the National Natural Science Foundation of China (21573183) and the Fundamental Research Funds for the Central Universities, China (20720160045)

Abstract: Direct methanol fuel cell (DMFC) is a potential clean energy facility because of abundant resources, easy storage, and high safety of methanol. However, the low activity, poor durability, and high price of the catalysts hamper the development of DMFC. High-index faceted nanocrystals usually show high catalytic activity for the electro-oxidation of small organic molecules due to high densities of low-coordinated surface sites. Surface modification is an alternative approach for improving catalyst performance via ligand effect or electronic effect. Herein, we prepared tetrahexahedral Pd nanocrystals (THH Pd NCs) enclosed by {730} high-index facets via electrochemical square-wave potential deposition, and modified the THH Pd NCs with Ru using cyclic voltammetry (CV). The coverages of Ru (θ_Ru) were controlled by limiting the CV cycles. The electrocatalytic performance of the Ru-modified THH Pd NCs for methanol oxidation was studied using CV in an alkaline methanol solution. We found that Ru modification can greatly reduce the onset and peak potentials of methanol electro-oxidation from -0.33 to -0.39 V and from -0.16 to -0.26 V, respectively. The current densities at -0.3 V during methanol electro-oxidation increased with increasing θ_Ru from 0 to 0.08, and decreased with increasing θ_Ru from 0.08 to 0.27. When θ_Ru was 0.08, the current density on the Ru-modified THH Pd NCs reached 1.5 mA∙cm^-2, which was 10 times higher than that achieved for the THH Pd NCs. To detect the products at molecular level during methanol electro-oxidation, in-situ electrochemical Fourier-transform infrared (FTIR) spectroscopy was applied. The spectra of both THH Pd NCs and Ru-modified THH Pd NCs (θ_Ru = 0.08) showed that both CO₂ and formate were produced. The band intensities of CO₂ and formate on Ru-modified THH Pd NCs (θ_Ru = 0.08) were 1.6- and 1.2-times larger than those of THH Pd NCs, respectively. However, the band intensity of CO_ad during methanol electro-oxidation was almost equal on the two catalysts, implying that the "CO poison path" is not suppressed by Ru modification. These results indicate that a small amount of Ru (θ_Ru = 0.08) modification is beneficial for the electrocatalytic oxidation of methanol by enhancing the "formate path" at low potential. Overall, this study illustrates the influence of Ru modification of THH Pd NCs on its catalytic performance in methanol electro-oxidation, which throws light on the synthesis and application of catalysts with high activities.

Key words:
• High-index facet
•  /  Tetrahexahedral Pd nanocrystal
•  /  Surface modification
•  /  Methanol

• 1. [1]

     钱慧慧, 韩潇, 肇研, 苏玉芹.物理化学学报, 2017, 33, 1822. doi: 10.3866/PKU.WHXB201705022Qian, H. H.; Han, X.; Zhao, Y.; Su, Y. Q. Acta Phys. -Chim. Sin. 2017, 33, 1822. doi: 10.3866/PKU.WHXB201705022

  2. [2]

     Bianchini, C.; Shen, P. K. Chem. Rev. 2009, 109, 4183. doi: 10.1021/cr9000995

  3. [3]

     Zhang, L.; Chang, Q.; Chen, H.; Shao, M. Nano Energy 2016, 29, 198. doi: 10.1016/j.nanoen.2016.02.044

  4. [4]

     Cao, D.; Lu, G. Q.; Wieckowski, A.; Wasileski, S. A.; Neurock, M. J. Phys. Chem. B 2005, 109, 11622. doi: 10.1021/jp0501188

  5. [5]

     Tian, N.; Zhou, Z. Y.; Sun, S. G.; Ding, Y.; Wang, Z. L. Science 2007, 316, 732. doi: 10.1126/science.1140484

  6. [6]

     Tian, N.; Zhou, Z. Y.; Yu, N. F.; Wang, L. Y.; Sun, S. G. J. Am. Chem. Soc. 2010, 132, 7580. doi: 10.1021/ja102177r

  7. [7]

     Housmans, T. H. M.; Koper, M. T. M. J. Phys. Chem. B 2003, 107, 8557. doi: 10.1021/jp034291k

  8. [8]

     Wang, C.; Chen, D. P.; Sang, X.; Unocic, R. R.; Skrabalak, S. E. ACS Nano 2016, 10, 6345. doi: 10.1021/acsnano.6b02669

  9. [9]

     Jana, R.; Subbarao, U.; Peter, S. C. J. Power Sources 2016, 301, 160. doi: 10.1016/j.jpowsour.2015.09.114

  10. [10]

      Li, S.; Lai, J.; Luque, R.; Xu, G. Energy Environ. Sci. 2016, 9, 3097. doi: 10.1039/C6EE02229D

  11. [11]

      Sulaiman, J. E.; Zhu, S.; Xing, Z.; Chang, Q.; Shao, M. ACS Catal. 2017, 7, 5134. doi: 10.1021/acscatal.7b01435

  12. [12]

      Lee, Y. W.; Kim, M.; Kim, Y.; Kang, S. W.; Lee, J. H.; Han, S. W. J. Phys. Chem. C 2010, 114, 7689. doi: 10.1021/jp9119588

  13. [13]

      Wang, X.; Choi, S. I.; Roling, L. T.; Luo, M.; Ma, C.; Zhang, L.; Chi, M.; Liu, J.; Xie, Z.; Herron, J. A.; et al. Nat. Commun. 2015, 6, 7594. doi: 10.1038/ncomms8594

  14. [14]

      Wang, X.; Tang, Y.; Gao, Y.; Lu, T. J. Power Sources 2008, 175, 784. doi: 10.1016/j.jpowsour.2007.10.011

  15. [15]

      Liu, Z.; Zhang, X.; Tay, S. W. J. Solid State Electrochem. 2012, 16, 545. doi: 10.1007/s10008-011-1378-8

  16. [16]

      Hu, S.; Scudiero, L.; Ha, S. ECS Trans. 2014, 64, 1121. doi: 10.1149/06403.1121ecst

  17. [17]

      Zhang, K.; Bin, D.; Yang, B.; Wang, C.; Ren, F.; Du, Y. Nanoscale 2015, 7, 12445. doi: 10.1039/C5NR02713F

  18. [18]

      Chen, Q. S.; Zhou, Z. Y.; Vidal-Iglesias, F. J.; Solla-Gullon, J.; Feliu, J. M.; Sun, S. G. J. Am. Chem. Soc. 2011, 133, 12930. doi: 10.1021/ja2042029

  19. [19]

      Liu, H. X.; Tian, N.; Brandon, M. P.; Zhou, Z. Y.; Lin, J. L.; Hardacre, C.; Lin, W. F.; Sun, S. G. ACS Catal. 2012, 2, 708. doi: 10.1021/cs200686a

  20. [20]

      周志有, 林建龙, 商淑静, 任洁, 孙世刚.物理化学学报, 2012, 28, 1745. doi: 10.3866/PKU.WHXB201205082Zhou, Z. Y.; Lin, J. L.; Shang, S. J.; Ren, J.; Sun, S. G. Acta Phys. -Chim. Sin. 2012, 28, 1745. doi: 10.3866/PKU.WHXB201205082

  21. [21]

      Ye, J. Y.; Jiang, Y. X.; Sheng, T.; Sun, S. G. Nano Energy 2016, 29, 414. doi: 10.1016/j.nanoen.2016.06.023

  22. [22]

      Samjeské, G.; Xiao, X. Y.; Baltruschat, H. Langmuir 2002, 18, 4659. doi: 10.1021/la011308m

  23. [23]

      Chen, A.; Ostrom, C. Chem. Rev. 2015, 115, 11999. doi: 10.1021/acs.chemrev.5b00324

  24. [24]

      Yang, Y. Y.; Ren, J.; Zhang, H. X.; Zhou, Z. Y.; Sun, S. G.; Cai, W. B. Langmuir 2013, 29, 1709. doi: 10.1021/la305141q

•