Leveraging Polar Discontinuities to Tune the Binding of Methanol on BCN and Graphene–BN Lateral Heterostructures

Leveraging Polar Discontinuities to Tune the Binding of Methanol on BCN and Graphene–BN Lateral Heterostructures

2021

We have performed density functional theory calculations to study the adsorption of methanol on graphene–BN lateral heterostructures and highly intermixed BCN, as well as on pure graphene and pure h-BN. We find that the adsorption energy is enhanced significantly on the heterostructures, obtaining the largest enhancement on a triangular graphene island embedded in a h-BN matrix with zigzag interfaces. We find that while the majority of the binding arises from London dispersion interactions, this enhancement is largely due to Keesom interactions, i.e., due to electrostatic interactions between the permanent electric dipole moment of the methanol molecule and permanent charges on the heterostructured substrates. These charges arise due to polar discontinuities at certain kinds of C–BN interfaces. We find a strong correlation between the adsorption energy and these interface charges. These results provide insight into experimental findings that methanol binds more strongly to BN-doped carbon foams than to plain carbon foam. Our findings suggest design principles for engineering materials for use in cooling devices that can be used to convert waste heat or solar energy into useful work, using thermal energy storage.

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