Selective electron perturbation via oxygen vacancies enables efficient nitrogen electroreduction

Area of Science:

• Materials Science
• Electrochemistry
• Catalysis

Background:

• Electrocatalytic nitrogen reduction reaction (NRR) is a promising sustainable ammonia production method.
• Challenges include inert N2 molecules and competing hydrogen evolution reaction (HER).

Purpose of the Study:

• To synthesize oxygen-vacancy-rich FeMoO4 nanoparticles (FMO-1) for enhanced electrocatalytic NRR.
• To investigate the role of oxygen vacancies in improving ammonia synthesis efficiency and selectivity.

Main Methods:

• Hydrothermal synthesis of FeMoO4 nanoparticles.
• Controlled Ar/H2 etching to create oxygen vacancies.
• Structural and spectroscopic characterizations (e.g., X-ray diffraction, X-ray photoelectron spectroscopy).
• Electrocatalytic performance testing for ammonia production.

Main Results:

• Oxygen vacancy formation altered the electronic environment of Fe sites, increasing the Fe2+/Fe3+ ratio.
• The optimized FMO-1 catalyst showed a two-fold performance enhancement compared to pristine FeMoO4.
• Oxygen vacancies strengthened N2 adsorption and activation on Fe sites.
• Improved selectivity for ammonia production due to regulated competitive adsorption.

Conclusions:

• Site-selective oxygen vacancy engineering is crucial for tuning adsorption thermodynamics in electrocatalysis.
• Fe-centered electronic reconstruction effectively suppresses HER and enhances NRR.
• This work presents a viable strategy for designing bimetallic oxide catalysts for ambient ammonia electrosynthesis.