Boosting electrocatalytic N₂ reduction by MnO₂ with oxygen vacancies

Area of Science:

• Materials Science
• Electrochemistry
• Catalysis

Background:

• Nitrogen (N2) reduction to ammonia (NH3) is crucial for agriculture and industry.
• Developing efficient and selective electrocatalysts for NH3 synthesis at neutral pH remains a significant challenge.
• Current electrocatalysts often suffer from low efficiency and poor stability.

Purpose of the Study:

• To experimentally verify the use of manganese dioxide with oxygen vacancies (MnOx) nanowire arrays for high-performance electrocatalytic N2 reduction.
• To investigate the role of oxygen vacancies in enhancing the catalytic activity and selectivity.
• To explore MnOx as a promising material for sustainable ammonia production.

Main Methods:

• Fabrication of MnOx nanowire arrays with controlled oxygen vacancies.
• Electrocatalytic performance testing for N2 reduction in neutral pH conditions.
• Density functional theory (DFT) calculations to elucidate the reaction mechanism.

Main Results:

• Achieved a high NH3 formation rate of 1.63 × 10-10 mol cm-2 s-1 and Faradaic efficiency of 11.40% with MnOx nanowires.
• Observed significantly enhanced performance compared to pristine MnO2.
• DFT calculations revealed that oxygen vacancies strengthen N2 adsorption via enhanced electronic interaction with Mn atoms.

Conclusions:

• Oxygen-deficient MnOx nanowire arrays are highly effective electrocatalysts for N2 reduction at neutral pH.
• Oxygen vacancies play a critical role in boosting N2 adsorption and subsequent electrocatalytic performance.
• This study provides a new strategy for designing advanced N2-fixing electrocatalysts through oxygen nonstoichiometry engineering.