Nanoscience and Microsystems ETDs

Publication Date

Summer 7-29-2025

Abstract

Platinum (Pt) and palladium (Pd) are critical components in diesel emission control systems, enabling the conversion of harmful pollutants under demanding conditions. However, Pt’s effectiveness is hindered by sintering under high-temperature oxidizing environments. This dissertation investigates how Pt and Pd evolve under oxidizing conditions at 800°C, highlighting their distinct thermodynamic behaviors and interactions. Using TEM, EDS, EELS, XRF, XRD, and EXAFS, we show that Pd suppresses Pt sintering by reducing the volatility of PtO₂, leading to the formation of stable particles. Both Pt and Pd are present in metallic and oxide states, forming biphasic 'Janus' particles with conjoined metal and oxide regions. We demonstrate that Pt moderates Pd oxidation, altering its mechanism and stabilizing the formation of these Janus structures. These particles enable continuous redistribution of mobile species, supporting self-healing behavior and sustained catalytic performance after prolonged aging. This work provides insight into metal–oxide phase stability in Pt-alloy systems and offers a pathway to design catalysts that meet Department of Energy targets—ultimately supporting cleaner air and improved public health.

Keywords

Self-healing catalysts, Diesel emission control, Bimetallic catalyst systems, Transmission electron microscopy (TEM), Janus particles, Vapor-phase transport

Document Type

Dissertation

Language

English

Degree Name

Nanoscience and Microsystems

Level of Degree

Doctoral

Department Name

Nanoscience and Microsystems

First Committee Member (Chair)

Abhaya Datye

Second Committee Member

Adrian Brearley

Third Committee Member

Nicholas Jaegers

Fourth Committee Member

John Watt

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