Work-Function-Dependent Reduction of Transition Metal Nitrides in Hydrogen Environments.
Abdul Rehman1, Robbert W E van de Kruijs1, Wesley T E van den Beld1
1Industrial Focus Group XUV Optics, MESA+ Institute for Nanotechnology, University of Twente, Drienerlolaan 5, 7522NB Enschede, Netherlands.
The work function of transition metal nitrides dictates their stability in hydrogen environments. Below a critical threshold, their reduction by hydrogen radicals ceases, enabling prediction of protective coating performance.
Area of Science:
- Materials Science
- Surface Science
- Hydrogen Embrittlement
Background:
- Growing demand for hydrogen in sustainable energy necessitates robust protective coatings.
- Understanding material stability in reactive hydrogen environments is critical but not fully elucidated.
- Transition metal nitrides (TMNs) are candidates for hydrogen-protective coatings.
Purpose of the Study:
- To identify key parameters governing the chemical stability of TMNs in reactive hydrogen.
- To establish a predictive model for the performance of TMNs as hydrogen-protective coatings.
- To elucidate the mechanism of TMN reduction by hydrogen radicals.
Main Methods:
- Investigated the reducibility (denitridation) of various transition metal nitrides (TMNs).
- Utilized elevated temperatures and reactive hydrogen radical (H*) environments.
- Correlated material reduction with the work function of the TMN system.
Main Results:
- The work function was identified as a critical parameter for TMN stability in hydrogen radicals.
- A threshold work function (ϕTH) was determined, below which TMN reduction significantly slows or stops.
- Preferential binding of H* to transition metal atoms, rather than nitrogen, inhibits volatile species formation.
Conclusions:
- The work function provides a novel metric for predicting the chemical stability of TMNs in hydrogen.
- This finding offers a new framework for understanding hydrogen-TM compound interactions.
- Enables rational design and selection of effective hydrogen-protective coatings.
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