Decoding the Stability-Activity Paradox in Electrochemical Ammonia Oxidation: An Operando Perspective.

Area of Science:

• Electrochemistry
• Materials Science
• Catalysis

Background:

• Electrochemical ammonia oxidation (AOR) is crucial for sustainable energy technologies like ammonia fuel cells and green hydrogen production.
• Current AOR systems face challenges with catalyst instability and degradation under harsh operating conditions (high pH, high potential).
• Catalyst deactivation mechanisms include metal dissolution, leaching, agglomeration, and poisoning by nitrogenous intermediates.

Purpose of the Study:

• To provide a perspective on the mechanistic pathways of AOR.
• To critically analyze the origins of catalyst deactivation in AOR systems.
• To highlight the importance of in situ characterization techniques for understanding catalyst behavior.

Main Methods:

• Discussion of noble and non-noble metal electrocatalysts for AOR.
• Investigation of the relationship between catalyst structure (coordination geometry, electronic structure) and stability.
• Review of electrochemical in situ techniques: X-ray absorption spectroscopy (XAS), Raman spectroscopy, and Fourier transform infrared (FTIR).

Main Results:

• Catalyst deactivation is linked to electronic structure, coordination geometry, and surface sensitivity.
• In situ techniques allow for the study of dynamic active site evolution and transient intermediates during AOR.
• Understanding these factors is essential for improving catalyst long-term stability and performance.

Conclusions:

• Strategic synthesis of electrocatalysts and advancements in operando techniques are needed for robust AOR systems.
• Durability engineering is critical for the rational development of sustainable ammonia oxidation technologies.
• Further research should focus on addressing catalyst poisoning and degradation for practical AOR applications.