Plasma-induced functionalization of graphitic surfaces: The role of nitrogen–argon gas mixtures

Graphite-based materials are crucial in state-of-the-art technologies, including energy conversion, energy storage and sensing, due to their exceptional electrical conductivity, stability and versatility. Tailoring their surface properties through environmentally friendly techniques is essential for optimizing their performance in diverse applications. This study investigates the effects of low-frequency plasma treatment on high-purity mineral graphite using various mixtures of nitrogen and argon gases. Plasma treatment was employed to systematically modify the surface properties and incorporate nitrogen functionalities. Advanced characterization methods, including scanning electron microscopy, X-ray diffraction, Raman spectroscopy, X-ray photoelectron spectroscopy and gas sorption analysis, were used to evaluate changes in morphology, chemical composition, microstructure and porosity/surface area. Plasma-treated samples exhibited notable surface restructuring, including thinner platelets, with minimal alterations to the overall pore structure. Nitrogen doping was achieved with nitrogen concentrations reaching 5.8 at.% for the 100 % nitrogen plasma-treated sample, primarily as pyridinic and graphitic nitrogen, enhancing the material’s catalytic and electronic properties. While slight structural disorder and defect formation were observed, the fundamental graphitic framework remained intact. This work provides valuable insights into the functionalization mechanisms and highlights the effectiveness of controlled plasma treatment for tailoring graphite surfaces to meet emerging technological demands. Image generated using AI depicting a purple plasma glow discharge interacting with a hexagonally structured graphene surface. • Low-frequency plasma used to functionalize high-purity graphite surfaces • N 2 /Ar mixtures enable controlled N incorporation up to 5.8 at.% • XPS reveals pyridinic and graphitic N as dominant incorporated species • Plasma treatment restructures surfaces without altering pore network • Plasma-treated graphite gains functionalities relevant for high-tech applications