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Structural Aspects of MoS Prepared by Atomic Layer Deposition for Hydrogen Evolution Reaction
Miika Mattinen1, Wei Chen2, Rebecca A Dawley3
1Department of Applied Physics and Science Education, Eindhoven University of Technology, P.O. Box 513, 5600 MB Eindhoven, The Netherlands.
ACS Catalysis
|July 11, 2024
Summary
Amorphous molybdenum sulfides show high activity for hydrogen evolution reaction (HER) after electrochemical activation. Tailored deposition methods offer insights into structure-activity relationships for these earth-abundant catalysts.
Area of Science:
- Materials Science
- Electrochemistry
- Catalysis
Background:
- Molybdenum sulfides (MoS) are earth-abundant electrocatalysts for the hydrogen evolution reaction (HER).
- Both crystalline and amorphous forms of MoS are investigated for HER applications in acidic media.
- Understanding the structure-activity relationship is crucial for optimizing catalyst performance.
Purpose of the Study:
- To prepare thin films of amorphous and crystalline molybdenum sulfides using plasma-enhanced atomic layer deposition.
- To investigate the structural and electrochemical properties of these materials for HER.
- To elucidate the activation mechanisms and structure-property correlations in MoS electrocatalysts.
Main Methods:
- Plasma-enhanced atomic layer deposition (PEALD) for synthesizing amorphous and crystalline MoS films.
- Electrochemical activation and characterization (overpotential measurements at 10 mA/cm2 in 0.5 M H2SO4).
- Ex situ and quasi in situ X-ray photoelectron spectroscopy (XPS) for structural analysis.
Main Results:
- Amorphous MoS films transform into highly HER-active amorphous MoS2 (overpotential 210-250 mV) after electrochemical activation.
- Initial film stoichiometry influences the structure, HER activity, and stability of amorphous MoS.
- Crystalline MoS2 catalysts show no structural changes upon activation, with overpotentials ranging from 300-520 mV.
Conclusions:
- PEALD provides a practical method for depositing tailored MoS HER electrocatalysts.
- Electrochemical activation significantly enhances the HER activity of amorphous MoS.
- Catalyst structure, particularly defects in crystalline MoS2, plays a critical role in HER performance.
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