Hydroxylation of Platinum Surface Oxides Induced by Water Vapor.

Rik V Mom,Axel Knop-Gericke

doi:10.1021/acs.jpclett.1c03927

Abstract

With its high stability and well-tuned binding strength for adsorbates, platinum is an excellent catalyst for a wide range of reactions. In applications like car exhaust purification, the oxidation of hydrocarbons, and fuel cells, platinum is exposed to highly oxidizing conditions, which often leads to the formation of surface oxides. To reveal the structure of these surface oxides, the oxidation of Pt in O2 has been widely studied. However, in most applications, H2O is also an important or even dominant part of the reaction mixture. Here, we investigate the interaction of H2O with Pt surface oxides using near-ambient-pressure X-ray photoelectron spectroscopy. We find that reversible hydroxylation readily occurs in H2O/O2 mixtures. Using time-resolved measurements, we show that O–OH exchange occurs on a time scale of seconds.

Highlights

With its high stability and well-tuned binding strength for adsorbates, platinum is an excellent catalyst for a wide range of reactions
Platinum plays a central role in catalysis, both in presentday technologies such as car exhaust treatment[1] and in future technologies such as fuel cell catalysis.[2]
Because Pt surface oxides are thought to be the catalytically active phase in many cases, knowledge of their structure is key to understanding the catalytic process

Summary

Introduction

With its high stability and well-tuned binding strength for adsorbates, platinum is an excellent catalyst for a wide range of reactions. 0.5 mbar of O2 at 473 K and subsequently exposed the samples to O2/H2O mixtures in the temperature range of 393−473 K (see section S1 of the Supporting Information for experimental details).

Results

Conclusion