Atomic-scale carbon framework reconstruction enables nitrogen-doping up to 33.8 at% in graphene nanoribbon

Abstract

Nitrogen-doping is well-known to be an effective and promising strategy to tune the electronic states and configurations of carbon materials for catalysis, energy conversion and storage. Since 2009, numerous investigations have demonstrated that the catalytic activity of the nitrogen-doped carbon materials can be improved with an increased doping concentration, yet, how to realize a high doping level remains a great challenge, and to what level remains an open and elusive question. Herein, we report an “in situ framework reconstruction of g-C3N4” that can provide a suitable and simple approach for Nitrogen-superdoping, where nitrogen vacancy formed at C-N = C site in the g-C3N4 framework help to activate adjacent C atoms that are endowed with unpaired electrons dwelling, thus, to be more active. Importantly, both density functional theory analyses and experiments reveal that they are energetically favorable to bond with an ethene molecule, reconstructing a π-bonded dual nitrogen-doped hexagonal-C ring that further acts as building block of the as-formed graphene nanoribbons. Finally, the nitrogen-doping level and the configuration can be finely tuned in a wide range, and up to 33.8 at% of nitrogen is homogenously doped. With the Nitrogen-superdoped graphene nanoribbons as counter electrodes in dye-sensitized solar cells, which have attracted wide attention due to their easy fabrication and relative high power conversion efficiency (PCE), a PCE of 8.60% is achieved. This present work represents a breakthrough in high-efficiency nitrogen-doping of carbon materials, and will fastly promote the chemistry, chemical engeering and material industry involved in carbon.