On-Surface Carbon Nitride Growth from Polymerization of 2,5,8-Triazido-s-heptazine

Carbon nitrides have recently come into focus for photo- and thermal catalysis, both as support materials for metal nanoparticles as well as photocatalysts themselves. While many approaches for the synthesis of three-dimensional carbon nitride materials are available, only top-down approaches by exfoliation of powders lead to thin-film flakes of this inherently two-dimensional material. Here, we describe an in situ on-surface synthesis of monolayer 2D carbon nitride films as a first step toward precise combination with other 2D materials. Starting with a single monomer precursor, we show that 2,5,8-triazido-s-heptazine can be evaporated intact, deposited on a single crystalline Au(111) or graphite support, and activated via azide decomposition and subsequent coupling to form a covalent polyheptazine network. We demonstrate that the activation can occur in three pathways, via electrons (X-ray illumination), via photons (UV illumination), and thermally. Our work paves the way to coat materials with extended carbon nitride networks that are, as we show, stable under ambient conditions.

Automated summary

Carbon nitrides have gained attention as support materials for metal nanoparticles and as photocatalysts themselves. A new method has been developed to synthesize monolayer 2D carbon nitride films on a single crystalline support through in situ on-surface synthesis. The activation of the carbon nitride films can occur through three pathways: electrons, photons, and thermal energy. This work opens up possibilities for coating materials with stable carbon nitride networks under ambient conditions.