ASM 2019

Poster (P69)


Effect of Surface Ni on Oxygen Reduction Reaction in Dealloyed Nanoporous PtNi

 

Venkataramana Imandi* and Abhijit Chatterjee*

*Indian Institute of Technology Bombay

*E-mail: abhijit[at]chem.iitb.ac.in

 High specific surface area nanoporous PtNi  synthesized via selective dissolution of Ni exhibits a high catalytic activity toward the oxygen reduction reaction (ORR). Using kinetic Monte Carlo simulations, we show that the elemental distribution in nanoporous PtNi is different from the well-understood Pt-skin PtNi catalyst. In nanoporous PtNi, both the surface and subsurface layer are rich in Pt. Crucially, a small amount of Ni is present in the surface layer. Using density functional theory, we show that the presence of Ni in the surface layer in nanoporous PtNi can speed up the ORR by orders of magnitude. Different PtNi atom arrangements in the surface layer are considered. Our simulations show that the OH formation step that is the rate-limiting step for the ORR is the same for the PtNi(111) surface. The low concentration of surface Ni explains why nanoporous PtNi provides only 10 times improvement in ORR rates over the pure Pt catalyst1.

 

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References:

(1) Venkataramana Imandi and Abhijit Chatterjee, Effect of surface Ni on oxygen reduction reaction in dealloyed nanoporous Pt-Ni, Ind. Eng. Chem. Res., 2018, DOI: 10.1021/acs.iecr.8b05204.

 

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