Simultaneous Graphite Exfoliation and N Doping in Supercritical Ammonia

Area of Science:

• Materials Science
• Nanotechnology
• Electrochemistry

Background:

• Graphene synthesis and doping are crucial for advanced applications.
• Nitrogen doping enhances graphene's electronic and catalytic properties.
• Developing efficient and scalable doping methods is essential.

Purpose of the Study:

• To report a novel method for simultaneous graphite exfoliation and graphene N-doping.
• To compare supercritical ammonia treatment with liquid-phase exfoliation using NH4OH.
• To evaluate the electrocatalytic performance of the N-doped graphene.

Main Methods:

• Graphite exfoliation and N-doping using supercritical ammonia.
• Liquid-phase exfoliation of graphite with NH4OH for N-doping.
• Characterization of N-doped graphene properties (layer number, flake size, defect density).
• Electrocatalytic testing for oxygen reduction reaction (ORR).

Main Results:

• Supercritical ammonia achieved 6.4 atom % N-doping in 2 hours, yielding few-layer graphene with large flake size and low defects.
• Liquid-phase exfoliation with NH4OH resulted in 2.7 atom % N-doping in 6 hours.
• N-doped graphene exhibited superior electrocatalytic activity, durability, and methanol tolerance compared to commercial Pt/C for ORR.

Conclusions:

• Supercritical ammonia is a highly effective agent for simultaneous graphite exfoliation and graphene N-doping.
• The resulting N-doped graphene possesses excellent quality and catalytic performance.
• This method offers a promising route for producing advanced graphene materials for energy applications.