New insights into the effects of alloying Pt with Ni on oxygen reduction reaction mechanisms in acid medium: a first-principles study

• Published in: Journal of molecular modeling 2015-11, Vol.21 (11), p.281-281, Article 281
• Main Author: Ou, Li-Hui
• Format: Article
• Language: English
• Subjects: Characterization and Evaluation of Materials; Chemistry; Chemistry and Materials Science; Computer Appl. in Life Sciences; Computer Applications in Chemistry; Molecular Medicine; Original Paper; Theoretical and Computational Chemistry
• ISSN: 1610-2940; 0948-5023
• DOI: 10.1007/s00894-015-2830-y

The effects of alloying Pt with transition metal Ni on oxygen reduction reaction (ORR) mechanisms was investigated based on a systematic density functional theory (DFT) calculation explored in the present work. New insights into the ORR mechanisms were reported at the atomic level on Pt-segregated Pt 3 Ni(111). Only one molecular chemisorption state with the end-on OOH configuration was identified through geometry optimization and minimum energy path (MEP) analysis; top-bridge-top configuration as observed on pure Pt(111) was not identified on Pt-segregated Pt 3 Ni(111), indicating that alloying Pt with Ni influences the intermediates of ORR, and leads to only the dissociation mechanism of chemisorption state OOH species being involved in acid medium on Pt-segregated Pt 3 Ni(111). By contrast, the dissociation mechanisms of chemisorbed O 2 molecule with top-bridge-top configuration and OOH species both were involved on pure Pt(111). The rds of the entire four-electron ORR was changed after Pt alloying with Ni. The rds of the entire ORR is the proton and electron transfer to O 2 to form OOH on Pt-segregated Pt 3 Ni(111), whereas it is the reaction of O atom protonation to form OH species on pure Pt(111), indicating that sublayer Ni strongly influences the rds of ORR. The comparison of the ORR mechanisms explained that Pt 3 Ni alloy enhanced the ORR electrocatalytic activity more than pure Pt. The effect of electrode potential on ORR pathway on the pure Pt and Pt 3 Ni alloy was considered to obtain further insights into the electrochemical reduction of O 2 . Results showed that the proton and electron transfer becomes difficult at high potential. The ORR can easily proceed when the electrode potential lowers. For pure Pt- and Pt-based alloys, this phenomenon may imply the origin of the overpotential.