Hydrogen reduction of molybdenum oxide at room temperature

The color changes in chemo- and photochromic MoO 3 used in sensors and in organic photovoltaic (OPV) cells can be traced back to intercalated hydrogen atoms stemming either from gaseous hydrogen dissociated at catalytic surfaces or from photocatalytically split water. In applications, the reversibil...

Full description

Saved in:
Bibliographic Details
Published in:Scientific reports 2017-01, Vol.7 (1), p.40761-40761, Article 40761
Main Authors: Borgschulte, Andreas, Sambalova, Olga, Delmelle, Renaud, Jenatsch, Sandra, Hany, Roland, Nüesch, Frank
Format: Article
Language:English
Subjects:
140/146
639/301/299/946
639/624/1075/1083
639/638/77/887
Color
High temperature
Humanities and Social Sciences
Hydrogen
Molybdenum
multidisciplinary
Nucleation
Oxides
Photovoltaics
Science
Sensors
Side reactions
Temperature effects
Thin films
Citations: Items that this one cites
Items that cite this one
Online Access:Get full text
Tags: Add Tag
No Tags, Be the first to tag this record!
Description
Summary:The color changes in chemo- and photochromic MoO 3 used in sensors and in organic photovoltaic (OPV) cells can be traced back to intercalated hydrogen atoms stemming either from gaseous hydrogen dissociated at catalytic surfaces or from photocatalytically split water. In applications, the reversibility of the process is of utmost importance, and deterioration of the layer functionality due to side reactions is a critical challenge. Using the membrane approach for high-pressure XPS, we are able to follow the hydrogen reduction of MoO 3 thin films using atomic hydrogen in a water free environment. Hydrogen intercalates into MoO 3 forming H x MoO 3 , which slowly decomposes into MoO 2 +1/2 H 2 O as evidenced by the fast reduction of Mo 6+ into Mo 5+ states and slow but simultaneous formation of Mo 4+ states. We measure the decrease in oxygen/metal ratio in the thin film explaining the limited reversibility of hydrogen sensors based on transition metal oxides. The results also enlighten the recent debate on the mechanism of the high temperature hydrogen reduction of bulk molybdenum oxide. The specific mechanism is a result of the balance between the reduction by hydrogen and water formation, desorption of water as well as nucleation and growth of new phases.
ISSN:2045-2322
2045-2322
DOI:10.1038/srep40761