Water Mediated Deactivation of Co3O4 Naonrods Catalyst for CO Oxidation and Resumption of Activity at and Above 373 K: Electronic Structural Aspects by NAPPES

The catalytic activity of the Co3O4 nanorods (NRs) for the CO oxidation reaction and the effect of water on the catalytic reaction have been explored with near-ambient pressure photoelectron spectroscopy (NAPPES) and mass spectral analysis. Comparative NAPPES studies have been employed to understand...

Full description

Saved in:
Bibliographic Details
Published in:Journal of physical chemistry. C 2017-09, Vol.121 (37), p.20296-20305
Main Authors: Jain, Ruchi, Reddy, Kasala Prabhakar, Ghosalya, Manoj Kumar, Gopinath, Chinnakonda S
Format: Article
Language:English
Online Access:Get full text
Tags: Add Tag
No Tags, Be the first to tag this record!
Description
Summary:The catalytic activity of the Co3O4 nanorods (NRs) for the CO oxidation reaction and the effect of water on the catalytic reaction have been explored with near-ambient pressure photoelectron spectroscopy (NAPPES) and mass spectral analysis. Comparative NAPPES studies have been employed to understand the elucidation of the catalytic reaction pathway and the evolution of various surface species. The results confirm the suppression of the CO oxidation activity on the Co3O4 NRs in the presence of water vapor. Various type of surface species, such as CO­(ads), hydroxyl, carbonate, formate, are found to be present on the catalyst surface depending on the reaction conditions. Vibrational features of CO, O2, and CO2 were observed and shift in binding energy of these features under the reaction conditions directly suggests a change in work function of the catalyst surface. Under dry conditions, CO couples with labile O atoms to form CO2; however, under wet conditions, CO predominantly interacts with surface OH groups resulting in the formation of carbonate and formate intermediates. In situ studies of oxidation of CO on Co3O4 shows that CO oxidation depends not only on surface Co3+ concentration but also influenced by Co3+/Co2+ ratio on the catalyst surface. The carbonate was found to be a reaction inhibitor at room temperature; however, it acts as an active intermediate at 375 K and above. Above the boiling point of water, Co3O4 NR surfaces begin to show the oxidation activity even in the presence of water vapor. The intrinsic role of intermediate species was used to derive a possible reaction mechanism under different reaction conditions.
ISSN:1932-7447
1932-7455
DOI:10.1021/acs.jpcc.7b05480