Adsorption of H2O, H2, O2, CO, NO, and CO2 on graphene/g-C3N4 nanocomposite investigated by density functional theory

Highlights: • The buckle graphene/g-C₃N₄ nanocomposite is more stable than the planar one. • Graphene as a substrate can significantly relax the buckle degree of g-C₃N₄ sheet. • Small molecules on graphene/g-C₃N₄ nanocomposite are physical adsorption. Motivated by the photocatalytic reactions of small molecules on g-C₃N₄ by these insights, we sought to explore the adsorption of H₂O and CO₂ molecules on the graphene side and H₂O, H₂, O₂, CO, NO, and CO₂ molecules on the g-C₃N₄ side of hybrid g-C₃N₄/graphene nanocomposite using first-principles calculations. The atomic structure and electronic properties of hybrid g-C₃N₄/graphene nanocomposite is explored. The adsorption of small molecules on graphene/g-C₃N₄ nanocomposite is thoroughly investigated. The computational studies revels that all small molecules on graphene/g-C₃N₄ nanocomposite are the physisorption. The adsorption characteristics of H₂O and CO₂ molecules on the graphene side are similar to that on graphene. The adsorption of H₂O, H₂, O₂, CO, NO, and CO₂ molecules on the g-C₃N₄ side always leads to a buckle structure of graphene/g-C₃N₄ nanocomposite. Graphene as a substrate can significantly relax the buckle degree of g-C₃N₄ in g-C₃N₄/graphene nanocomposite.