Multi-Scale Modeling for Plasma-Enhanced Ammonia Decomposition over Carbides and Nitrides

Area of Science:

• Catalysis
• Plasma Science
• Materials Chemistry

Background:

• Ammonia (NH3) is a promising carbon-free hydrogen carrier.
• High temperatures and costly ruthenium catalysts are typically needed for ammonia decomposition due to the strong N-N bond.
• Developing energy-efficient hydrogen production methods is crucial.

Purpose of the Study:

• To investigate how non-thermal plasma (NTP) can enable low-temperature ammonia decomposition.
• To elucidate the catalytic mechanisms of cobalt-based carbides and nitrides under NTP.
• To benchmark performance against ruthenium and cobalt catalysts.

Main Methods:

• Multiscale modeling framework combining density functional theory (DFT), zero-dimensional plasma kinetics, and microkinetic modeling.
• Analysis of reaction pathways and activation barriers for ammonia decomposition.
• Benchmarking catalyst performance under thermal and plasma conditions.

Main Results:

• Cobalt-based carbides and nitrides show enhanced activity for ammonia decomposition under NTP.
• NTP promotes a radical-driven coupling pathway, shifting the rate-limiting step.
• Turnover frequencies increased by up to 6 orders of magnitude, lowering required temperatures significantly.

Conclusions:

• Co-based carbides and nitrides are effective plasma-active catalysts for ammonia decomposition.
• NTP enables a more energy-efficient pathway for hydrogen production from ammonia.
• This research identifies promising catalysts for sustainable hydrogen generation.