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Published on: June 9, 2023
Interplay between defect structure and catalytic activity in the Mo(10-x)V(x)O(y) mixed-oxide system
Peter Jakes1, Nina Blickhan, Tim Jekewitz
1Institut für Physikalische Chemie, Universität Freiburg, Albertstr. 21, 79104 Freiburg, Germany.
Summary
This study reveals that molybdenum-vanadium oxide (Mo(10-x)V(x)O(y)) systems exhibit optimal catalytic activity when vanadium acts as an acceptor center, forming oxygen vacancies. Electron paramagnetic resonance spectroscopy identified key vanadyl species influencing semiconductor properties.
Area of Science:
- Solid-state chemistry
- Materials science
- Catalysis
Background:
- Molybdenum-vanadium oxide (Mo(10-x)V(x)O(y)) systems are crucial in heterogeneous catalysis.
- Understanding their defect chemistry and semiconductor properties is key to optimizing performance.
Purpose of the Study:
- To investigate the defect chemistry and semiconductor properties of Mo(10-x)V(x)O(y) solid-solution systems.
- To correlate these properties with catalytic activity.
Main Methods:
- Electron paramagnetic resonance (EPR) spectroscopy was employed to study Mo(10-x)V(x)O(y) systems.
- Quantitative analysis of vanadyl (VO(2+)) species concentration as a function of Mo/V ratio.
Main Results:
- Paramagnetic vanadyl (VO(2+)) species were identified, with maximal concentration at Mo(5)V(5)O(y).
- Mo(10-x)V(x)O(y) exhibits p-type semiconducting properties for Mo(9)V(1)O(y)-Mo(5)V(5)O(y) and switches to n-type for Mo(5)V(5)O(y)-Mo(1)V(9)O(y).
- Highest catalytic activity correlates with vanadium acting as an acceptor center, leading to the formation of oxygen vacancies (ν(··)(O)) for charge compensation.
Conclusions:
- The concentration and distribution of VO(2+) and oxygen vacancies (ν(··)(O)) in both bulk and surface are critical for heterogeneous catalysis in Mo(10-x)V(x)O(y) systems.
- Defect chemistry significantly influences the semiconductor type (p-type or n-type) and catalytic performance.
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