Effects of Zr dopants on properties of PtNi nanoparticles for ORR catalysis: A DFT modeling

Pt-based alloys, such as Pt₃Ni, are among the best electrocatalysts for oxygen reduction reaction (ORR) in polymer electrolyte membrane fuel cells. Doping of PtNi alloys with Zr was shown to enhance the durability of the operating ORR catalysts. Rationalizing these observations is hindered by the absence of atomic-level data for these tri-metallic materials, even when not exposed to the fuel cell operation conditions. This study aims at understanding structure–property relations in Zr-doped PtNi nanoparticles as a key to their ORR function. In particular, we calculated, using a method based on density functional theory, the most stable chemical orderings of pristine and Zr-doped Pt₃Ni particles containing over 400 atoms. We thus clarify (i) preferential location and charge states of Zr atoms in the Pt₃Ni NPs; (ii) effect of doping Zr atoms on the stability of the Pt skin of the Pt₃Ni NPs; (iii) charge redistribution induced by Zr dopants; (iv) layer-by-layer atomic ordering in the Pt₃Ni/Zr NPs with the increasing Zr content; and (v) effect of Zr atoms on the adsorption energies of O and OH species as indicators of the ORR activity.

This work was supported by HPC-Europa3, supported by the European Commission H2020 Research and Innovation, Grant Agreement No. 730897 (Grant No. HPC17QU8IV for B.V.M., Transnational Access program, Barcelona Supercomputing Center); Spanish/FEDER Ministerio de Ciencia, Innovación y Universidades (Grant Nos. PID2021-128217NB-I00, MDM-2017-0767, and CEX2021-001202-M); Generalitat de Catalunya [Grant Nos. 2018BP00190 (for A.B.) and 2021SGR00286]; and Junior Leader Program from “La Caixa Foundation” (for A.B.). K.M.N. thanks Professor J. Libuda and Professor A. Görling for their hospitality at the CLINT Center (FAU-Erlangen, Germany) during the preparation of this article for publication. This study was also supported by the European COST Actions under Grant Nos. CA18234 and CA21101.

The data that support the findings of this study are available within the article and are openly available in the ioChem-BD repository at http://doi.org/10.19061/iochem-bd-6-325.⁴⁹ 

The authors have no conflicts to disclose.