Grain-Boundary-Induced Ultrasensitive Molecular Detection of Graphene Film

Graphene has been considered a promising platform for molecular detection due to the graphene-enhanced Raman scattering (GERS) effect. However, the GERS performance of pristine graphene is limited by a low chemically active surface and insufficient density of states (DOS). Although diverse defects have been introduced, it remains a great challenge to improve the enhancement performance. Here, we show that graphene grain boundaries (GBs) possess stronger adsorption capacity and more abundant DOS. Thus, GERS performance increases with the atomic percentage of GBs, which makes nanocrystalline graphene (NG) film a superior GERS substrate. For R6G as a probe molecule, a low detection limit of 3 x 10-10 M was achieved. Utilizing the high chemical activity of GBs, we also fabricated NG film decorated with Au particles using a one-step quenching strategy, and this hybrid film exhibits an extremely low limit of detection down to 5 x 10-11 M, outperforming all the reported graphene-based systems.

Automated summary

Graphene grain boundaries possess stronger adsorption capacity and more abundant density of states (DOS), which can improve the graphene-enhanced Raman scattering (GERS) performance. Utilizing this characteristic, superior nanocrystalline graphene (NG) film can be fabricated as a detection platform. The NG film decorated with Au particles exhibits an extremely low detection limit, outperforming other reported graphene-based systems.