Ab initio calculations of edge-functionalized armchair graphene nanoribbons: Structural, electronic, and vibrational effects

TL;DR

This study uses ab initio calculations to explore how hydroxyl edge functionalization affects the structure, electronic properties, and vibrational modes of armchair graphene nanoribbons, revealing tunable band-gaps and Raman signatures.

Contribution

It provides the first detailed theoretical analysis of hydroxyl functionalized AGNRs, demonstrating tunable electronic properties and vibrational signatures for potential experimental applications.

Findings

Edge functionalization stabilizes AGNRs.

Band-gap decreases linearly with hydroxyl groups.

Raman modes shift with functionalization degree.

Abstract

We present a theoretical study on narrow armchair graphene nanoribbons (AGNRs) with hydroxyl functionalized edges. Although this kind of passivation strongly affects the structure of the ribbon, a high degree of edge functionalization proves to be particularly stable. An important consequence of the geometric deviations is a severe reduction of the band-gap of the investigated 7-AGNR. This shift follows a linear dependence on the number of added hydroxyl groups per unit cell and thus offers the prospect of a tunable band-gap by edge functionalization. We furthermore cover the behavior of characteristic phonons for the ribbon itself as well as fingerprint modes of the hydroxyl groups. A large down-shift of prominent Raman active modes allows the experimental determination of the degree of edge functionalization.