Origin of Stability and Activity Enhancements in Pt-based Oxygen Reduction Reaction Catalysts via Defect-Mediated Dopant Adsorption.

Autor: Sawant KJ; Davidson School of Chemical Engineering, Purdue University, West Lafayette, IN 47907, USA., Zeng Z; Davidson School of Chemical Engineering, Purdue University, West Lafayette, IN 47907, USA., Greeley JP; Davidson School of Chemical Engineering, Purdue University, West Lafayette, IN 47907, USA.
Jazyk: angličtina
Zdroj: Angewandte Chemie (International ed. in English) [Angew Chem Int Ed Engl] 2024 Jan 25; Vol. 63 (5), pp. e202312747. Date of Electronic Publication: 2023 Dec 22.
DOI: 10.1002/anie.202312747
Abstrakt: Platinum alloys are highly efficient electrocatalysts for the oxygen reduction reaction (ORR) in acidic conditions. However, these alloys are susceptible to metal loss through leaching and degradation, leading to reduced catalyst stability and activity. Recently, it has been shown that doping with oxophilic elements can significantly alleviate these problems, with a prominent example being Mo-doped Pt alloys. Here, to achieve atomic scale understanding of the exceptional activity and stability of these alloys, we present a detailed density functional theory description of the dopants' structures and impact on electrocatalyst properties. Beginning with the Mo/Pt system, we demonstrate that Mo can be stabilized in the form of low-dimensional oxyhydroxide moieties on Pt defects. The resulting structures enhance stability and activity via distinct physical processes, with the Mo moieties both directly inhibiting Pt dissolution at defects and indirectly enhancing ORR activity by generation of strain fields on surrounding Pt terraces. We then generalize these analyses to other metal dopant elements, and we demonstrate that similar low-dimensional oxyhydroxide structures control the electrocatalytic properties through an intricate interplay of the structures' acid stability, intrinsic activity for the ORR, and ability to induce ORR-promoting strain fields on Pt.
(© 2023 The Authors. Angewandte Chemie International Edition published by Wiley-VCH GmbH.)
Databáze: MEDLINE
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