Direct transfer of CVD-grown graphene onto eco-friendly cellulose film for highly sensitive gas sensor

In this study, cellulose flexible film was used as a supporting substrate for the development of an eco-friendly graphene gas sensor. The flexible cellulose substrate was fabricated by the method reported in the previous study. Graphene was grown on Cu foil using a conventional CVD method and directly transferred onto the cellulose substrate via a wet-transfer method. The results of conductivity, Raman spectroscopy, and SEM images confirmed that graphene was well-transferred onto the cellulose substrate without noticeable cracks. The performance of graphene gas sensors was measured by monitoring the current change according to the periodic injection of NO₂ target and N₂ purging gases. The graphene gas sensor built on cellulose film exhibited superior sensing performance compared to graphene on SiO₂, mainly due to the functional groups in cellulose film. In addition, the incorporation of halloysite nanotube into cellulose film enhanced the sensitivity of the graphene sensor much more because the surface area of the transferred graphene became larger. This study demonstrates that the highly sensitive graphene gas sensor could be fabricated by the use of ecofriendly cellulose film as a supporting substrate.