Virginia Tech
Interaction of Na, O₂, CO₂ and water on MnO(100): Modeling a complex mixed oxide system for thermochemical water splitting
Abstract
dc:description.abstractA catalytic route to hydrogen production via thermochemical water splitting is highly desirable because it directly converts thermal energy into stored chemical energy in the form of hydrogen and oxygen. Recently, the Davis group at Caltech reported an innovative low-temperature (max 850°C) catalytic cycle for thermochemical water splitting based on sodium and manganese oxides (Xu, Bhawe and Davis, PNAS, 2012). The key steps are thought to be hydrogen evolution from a Na₂CO₃/MnO mixture, and oxygen evolution by thermal reduction of solids formed by Na⁺ extraction from NaMnO₂. Our work is aimed at understanding the fundamental chemical processes involved in the catalytic cycle, especially the hydrogen evolution from water. In this project, efforts are made to understand the interactions between the key components (Na, O₂, CO₂, and water) in the hydrogen evolution steps on a well-defined MnO(100) single crystal surface, utilizing x-ray photoelectron spectroscopy (XPS), low energy electron diffraction (LEED) and temperature programmed desorption (TPD). While some of the behavior of the catalytic system is observed with the model system developed in this work, hydrogen is only produced from water in the presence of metallic sodium, in contrast to the proposal of Xu et al. that water splitting occurs from the reaction of water with a mixture of Na₂CO₃ and MnO. These differences are discussed in light of the different operating conditions for the catalytic system and the surface science model developed in this work.
Degree
thesis:*- Name thesis:degree_name
- Ph. D.
- Level thesis:degree_level
- doctoral
- Discipline thesis:degree_discipline
- Chemical Engineering
- Department dc:contributor.department
- Chemical Engineering
- Grantor dc:publisher
- Virginia Tech
- Year dc:date.issued
- 2015
Author and committee
dc:creator, dc:contributor.*- Author dc:creator
-
- Feng, Xu
- Chair dc:contributor.committeechair
-
- Cox, David F.
- Committee members dc:contributor.committeemember
-
- Ducker, William A.
- Davis, Richey M.
- Lu, Chang
Subjects
dc:subject × 8Rights
dc:rights- Statement dc:rights
-
- In Copyright
- Licence dc:rights.uri
Identifiers
dc:identifier.*- Dc Identifier Other
- vt_gsexam:6487
- OAI identifier oai:identifier
- oai:vtechworks.lib.vt.edu:10919/77378