Graphene-oxide (GO) nano-sheets: Lateral and vertical size-effects on chemical-gas sensitivity enhancement

The paper reports a size-effect of graphene-oxide (GO) nano-sheets on sensitivity of chemical-gas detection. By using resonant-cantilevers to measure molecule-adsorbing induced mass, the size-effect is classified as in-plane dimension lateral-effect and vertical thickness-effect. Based on detection of both reducing-gas of NH3 and oxidizing-gas of NO2, this research clearly reveals that, lateral-dimension size-effect plays a decisive role in sensitivity enhancement to reducing-gas, while thickness size-effect dominates the sensitivity to oxidizing-gas.

Introduction

Featuring two dimensional (2D) electronic principles and high surface-to-volume ratio, graphene-oxide (GO) nano-sheets are expected to be explored as excellent nano-materials for trace-level bio/chemical sensing. To date, with the graphene-based sensors, many kinds of bio/chemical molecules have been detected. For example, Novoselov and co-authors reported that even individual gas molecule could be detected by using single-layer graphene nano-device [1]. With resonant micro-cantilever as mass-type sensing platform, our previous reports also indicate that GO nano-sheets could be used as sensing material for sub-ppm NH3 or sub-ppb TNT explosive detecting [2]–[4]. It should be mentioned that the previous researches are focused on sensing performance improvement based on the merit of high specific surface area of GO nanosheets.