Shaping the empty carbon nanocubes: the role of Nitrogen. Insight from X-Ray Raman scattering spectroscopy at the N K-edge

Carbon nanomaterials have gained significant attention because of their unique tunable properties, including high surface area, excellent electrical conductivity, and chemical stability. These materials are classified by dimension, including 0D carbon quantum dots, 1D nanofibers, 2D nanosheets, and 3D hierarchical nanostructures such as hollow nanocages. Hollow carbon nanocages exhibit distinct characteristics, such as interior cavities and subnanometer channels, which enhance their structural stability and electrocatalytic efficiency. Furthermore, these structures, particularly when doped with heteroatoms like nitrogen, offer promising applications in energy storage, conversion, and sensing technologies. Nitrogen doping significantly influences the electronic properties, creating additional energy levels and active catalytic sites. Doping also facilitates extreme bending of the graphene planes, which improves electrocatalytic performance by enhancing oxygen reduction reactions and increasing active site density. This paper demonstrates, through both experimental and theoretical methods, that nitrogen atoms preferentially accumulate at the edges of carbon nanocages, inducing curvature in the graphitic structure. This finding provides insight into how heteroatom doping can be leveraged to tune the structural and electrochemical properties of carbon nanomaterials for advanced applications.