Potential Application of h-BNC Structures in SERS and SEHRS Spectroscopies: A Theoretical Perspective

Abstract

In this work, the electronic and optical properties of hybrid boron-nitrogen-carbon structures (h-BNCs) with embedded graphene nanodisks are investigated. Their molecular affinity is explored using pyridine as model system and comparing the results with the corresponding isolated graphene nanodisks. Time-dependent density functional theory (TDDFT) analysis of the electronic excited states was performed in the complexes in order to characterize possible surface and charge transfer resonances in the UV region. Static and dynamic (hyper)polarizabilities were calculated with coupled-perturbed Kohn-Sham theory (CPKS) and the linear and nonlinear optical responses of the complexes were analyzed in detail using laser excitation wavelengths available for (Hyper)Raman experiments and near-to-resonance excitation wavelengths. Enhancement factors around 103 and 108 were found for the polarizability and first order hyperpolarizability, respectively. The quantum chemical simulations performed in this work point out that nanographenes embedded within hybrid h-BNC structures may serve as good platforms for enhancing the (Hyper)Raman activity of organic molecules immobilized on their surfaces and for being employed as substrates in surface enhanced (Hyper)Raman scattering (SERS and SEHRS). Besides the better selectivity and improved signal-to-noise ratio of pristine graphene with respect to metallic surfaces, the confinement of the optical response in these hybrid h-BNC systems leads to strong localized surface resonances in the UV region. Matching these resonances with laser excitation wavelengths would solve the problem of the small enhancement factors reported in Raman experiments using pristine graphene. This may be achieved by tuning the size/shape of the embedded nanographene structure.

Hierarchical Assembly of a Micro‐ and Macroporous Hydrogen‐Bonded Organic Framework with Tailored Single‐Crystal Size

“…The measured zeta potentials for carbon and silica particles are −0.67 and −0.14 mV, respectively, which suggests that the preferential adsorption of carbon particles is not caused by electrostatic interactions on the crystal surface. A possible explanation of the preferential adsorption of carbon particles could be due to the π‐π stacking interactions between the extended aromatic framework forming the MM‐TPY crystals and the graphene layers from the activated carbon particles [32] . The presented experiments are just a simple example of the potential of hierarchical porosity, which suggests that these materials with hierarchical nature and increased surface area to volume ratios could be used in future for different applications that require separation of solids and selective extraction of molecular species in solution, such as environmental recycling of materials, [33] dual drug delivery of biological samples, [34] and dual recycling of graphite and dyes [35] …”

Synthesis and Applications of Organic Borazine Materials

“…These include the use of organoborazines as ceramic precursors, [ 170 ] energetic materials (e.g., explosives), [ 175‐177 ] gas, [ 184 ] and contaminants [ 178 ] sensing, non‐linear [ 163 ] and linear optics, [ 180 ] and enhancement of Raman spectroscopy. [ 181,183 ]…”

“…These include the use of organoborazines as ceramic precursors, [170] energetic materials (e.g., explosives), [175][176][177] gas, [184] and contaminants [178] sensing, non-linear [163] and linear optics, [180] and enhancement of Raman spectroscopy. [181,183] The ultimate aim of this review is to stimulate discussion on the missing developments in this century-long investigation of the inorganic benzene ring, and the difference it makes in crafting novel materials.…”

On the adsorption affinity of graphene and white graphene sheets by dioxin‐like pollutants

“…Even more interesting are 2D hybrid materials based on boron, nitrogen and carbon, also called h‐BNCs [50–52], where the optical activity of the surface may be easily tuned. In these materials, graphene or white graphene nanoislands of different size may be “stamped,” whose optical response depends on the size and shape of the corresponding nanoisland [53–56].…”