Amphiphilicity of Intricate Layered Graphene/g-C3N4 Nanosheets

A Priyadarsini and BS Mallik, JOURNAL OF PHYSICAL CHEMISTRY B, 125, 11697-11708 (2021).

DOI: 10.1021/acs.jpcb.1c05609

The hybrid heterostructure of the tri-s-triazine form of graphitic carbon nitride (g-C3N4), a stable two-dimensional material, results from intricate layer formation with graphene. In this material, g-C3N4, an amphiphilic material, stabilizes Pickering emulsions as an emulsifier and can effectively disperse graphene. Due to the various technological applications of the hybrid nanosheets in an aqueous environment, it is essential to study the interaction of water molecules with graphene and g-C3N4 (Gr/g-C3N4)-combined heterostructure. Although few studies have been performed signifying the water orientation in the interfacial layer, we find that there is a lack of detailed studies using various dynamical and structural properties of the interfacial water molecules. The interface of the Gr/g-C3N4 hybrid structure, one of the rarely found amphiphilic interfaces (on the g-C3N3 side), is appropriate for exploring the water affinity due to the availability of heterogeneous interfacial aqueous interactions. We adopted classical molecular dynamics simulations using two models for water molecules to study the structure and dynamics of an aqueous interface. We have correlated the structural properties to dynamics and spectral properties to understand the overall behavior of the amphiphilic interface. Our results branch into two significant hydrogen bond (HB) properties in HB count and HB strength among the water molecules in the different layers. The HB counts in the different layers of water are correlated using the average distance distribution (PrO4), tetrahedral order parameters, HB donor/acceptor count, and total HBs per water molecule. A conspicuous difference is found in the HB count and related dynamics of the system. The HB lifetime and diffusion coefficient hint at the equivalent strength of HBs in the different layers. All the findings conclude that the amphiphilicity of the Gr/g-C3N4 interface can help in understanding various interfacial physical and chemical processes.

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