Bandgap evolution in nanographene assemblies

Computational analysis of linear chain of holey nanographene and their molecular characterizations

CONTEXT

Holey nanographene, an allotrope of carbon arranged in two dimensions, has gained remarkable attention as a nanomaterial with several potential uses in numerous industries, such as electronics, energy storage, healthcare, and environmental cleanup, because of its high carrier mobility, flexibility, transparency, high surface area, conductivity, and chemical stability. The fundamental holey nanographene is assembled in a linear form to create the holey nanographene chain (HNC) that is being discussed. To fully utilize it in various applications, it is essential to comprehend the basic ideas guiding its behavior at the nanoscale; for that, we find various topological indices for this holey nanographene chain using the cut method. Because topological indices are a robust mathematical tool that links molecular structure with chemical, physical, and biological properties, they are essential in diverse areas, namely chemistry, pharmaceutical research, environmental science, and materials science METHODS: The cut method is essential for calculating topological indices in large structures as standard definitions become increasingly complex for such computations. In this study, we apply the cut method to compute each topological index for holey nanographene structures, which involves extensive summations. MATLAB software is employed to simplify these calculations. To generate the DDSV (Distance Degree Sequence Vector) for each vertex within any dimension of holey nanographene, we utilize the NEWGRAPH interface. Python code is then used to analyze the DDSVs assigned to each vertex. Additionally, MATLAB code is applied to validate the numerical results derived from analytical formulae for the topological indices of the HNCs under consideration.

Unveiling Structural Variations in Armchair-Edge Coronoids by Spectroscopies

This study explores the electronic and vibrational properties of armchair coronoids (ACs), a unique class of polycyclic aromatic hydrocarbons with varying molecular and cavity sizes. Through density functional theory simulations, we investigated the X-ray photoelectron spectroscopy (XPS) and Raman spectra of C222, C114, C42, and their derivatives with different cavity sizes. The results reveal that band gaps and electronic properties of ACs can be precisely tuned by adjusting the molecular and cavity dimensions. XPS spectra demonstrated shifts in binding energy correlating with bandgap variations, while Raman spectra exhibited distinct C-C stretching and breathing modes. Notably, the introduction of cavities led to shifts in the breathing mode band, providing insights into the structural identification of ACs through Raman spectroscopy. The findings suggest that combining XPS and Raman spectroscopy can effectively characterize ACs, offering a comprehensive understanding of their structure-property relationships. This research lays the groundwork for future experimental and theoretical studies on the potential applications of ACs in electronic materials.

Recent progress in on-surface synthesis of nanoporous graphene materials

Nanoporous graphene (NPG) materials are generated by removing internal degree-3 vertices from graphene and introducing nanopores with specific topological structures, which have been widely explored and exploited for applications in electronic devices, membranes, and energy storage. The inherent properties of NPGs, such as the band structures, field effect mobilities and topological properties, are crucially determined by the geometric structure of nanopores. On-surface synthesis is an emerging strategy to fabricate low-dimensional carbon nanostructures with atomic precision. In this review, we introduce the progress of on-surface synthesis of atomically precise NPGs, and classify NPGs from the aspects of element types, topological structures, pore shapes, and synthesis strategies. We aim to provide a comprehensive overview of the recent advancements, promoting interdisciplinary collaboration to further advance the synthesis and applications of NPGs.