Microporous Carbon Nitride (C₃N_5.4) with Tetrazine based Molecular Structure for Efficient Adsorption of CO₂ and Water

Mesoporous carbon nitrides with C₃N₅ and C₃N₆ stoichiometries created a new momentum in the field of organic metal-free semiconductors owing to their unique band structures and high basicity. Here, we report on the preparation of a novel graphitic microporous carbon nitride with a tetrazine based chemical structure and the composition of C₃N_5.4 using ultra-stable Y zeolite as the template and aminoguanidine hydrochloride, a high nitrogen-containing molecule, as the CN precursor. Spectroscopic characterization and density functional theory calculations reveal that the prepared material exhibits a new molecular structure, which comprises two tetrazines and one triazine rings in the unit cell and is thermodynamically stable. The resultant carbon nitride shows an outstanding surface area of 130.4 m² g⁻¹ and demonstrates excellent CO₂ adsorption per unit surface area of 47.54 μmol m⁻², which is due to the existence of abundant free NH₂ groups, basic sites and microporosity. The material also exhibits highly selective sensing over water molecules (151.1 mmol g⁻¹) and aliphatic hydrocarbons due to its unique microporous structure with a high amount of hydrophilic nitrogen moieties and recognizing ability towards small molecules.