Understanding adsorbate-induced surface segregation in PtCo/C electrocatalyst

作者：Budiman Abdul Hamid; Purwanto Widodo Wahyu^*; Dewi Eniya Listiani; Dalimi Rinaldy; Hwang Bing Joe

来源：Asia-Pacific Journal of Chemical Engineering, 2012, 7(4): 604-612.

DOI：10.1002/apj.613

• XRD
• XAS
• phase segregation
• coordination number
• alloying extent

The X-ray diffraction (XRD) was used to study the effect of treatment on particle size and catalyst structure of PtCo/C electrocatalysts. The XRD showed the grain sizes of N2-treated electrocatalysts increase with temperature treatment, while those treated with CO remain the same. The X-ray absorption spectroscopy (XAS) was used to study the changes in atomic distribution, extent of alloying as well as the surface population of PtCo/C nanoparticles. The XAS revealed that the time of CO treatments influence the surface population due to phase segregation. Catalysts treatment for 1, 3 and 5 h lead to higher population of Pt on the core and Co on the surface resulting in Pt rich in coreCo rich in shell. In contrast, CO treatments for 7, 10 and 15 h lead to higher population of Pt on the shell and Co on the core resulting in Pt rich in shellCo rich in core. The electrochemical results showed that PtCo/C CO-treatment is more active than commercial PtCo/C for the oxygen reduction reaction and it is found that PtCo/C CO-treatment 3 h has the highest catalytic activity; because it has higher JPt and JCo values, indicating a higher extent of Pt and Co alloying.

• 出版日期2012-8