Enhanced oxygen reduction activity ofα-MnO₂by NH₃plasma treatment

Area of Science:

• Materials Science
• Electrochemistry
• Catalysis

Background:

• Oxygen vacancies and heteroatom doping are crucial for enhancing the oxygen reduction activity of metal oxides.
• Developing efficient catalyst modification methods is a key challenge in catalysis research.
• Room temperature plasma treatment offers a mild, efficient, and emission-free method for catalyst modification.

Purpose of the Study:

• To investigate the simultaneous introduction of oxygen vacancies and nitrogen doping onto alpha-manganese dioxide (α-MnO2) nanorods using ammonia plasma treatment.
• To evaluate the impact of this modification on the oxygen reduction reaction (ORR) activity.
• To assess the performance of the modified catalyst in magnesium-air (Mg-air) batteries.

Main Methods:

• Hydrothermal synthesis of α-MnO2 nanorods.
• Room temperature ammonia (NH3) plasma treatment of the synthesized α-MnO2 nanorods.
• Electrochemical characterization of oxygen reduction activity.
• Performance testing in Mg-air battery configurations.

Main Results:

• Ammonia plasma treatment successfully introduced oxygen vacancies and nitrogen doping onto the α-MnO2 surface.
• The N-doped MnO2 exhibited significantly enhanced oxygen reduction activity, with a half-wave potential of 0.84 V and a limiting current density of 6.32 mA cm⁻².
• The Mg-air battery utilizing N-doped MnO2 achieved a maximum power density of 76.3 mW cm⁻² with stable discharge performance.

Conclusions:

• Simultaneous introduction of oxygen vacancies and N doping via room temperature NH3 plasma treatment is an effective strategy to boost the ORR activity of α-MnO2.
• The enhanced catalytic performance makes N-doped MnO2 a promising cathode material for Mg-air batteries.
• This work presents a novel, efficient, and cost-effective method for catalyst development.