Nanopore Size-Dependent Raman Spectroscopy of Two-Dimensional γ‑Graphyne

Graphynes are allotropes of carbon that display both sp and sp ² carbons, which form acetylene- and benzene-like units, respectively, connected in a single-atomic layer structure. The sp-sp ² networks display rich structural patterns, with different physical and chemical properties, promising for clean energy generation and storage, optoelectronics, heat dissipation, and molecular filter applications. Here, we apply density-functional theory calculations to simulate the structure and Raman spectrum of γ-graphyne monolayers with one to six acetylene units between its carbon rings. Ready-to-use general formulas relating the lattice parameter, nanopore size, and number of Raman-active lattice vibrations to N are given. The wavenumber dependence of the G, G', Y, and Y' modes on N reveals differences of the order of tens of cm^-1. These results provide tools for fast and reliable identification of the N-type γ-graphynes, which is key for the architecture design of molecular filters and other nanodevices.