High-sensitivity NH3 gas sensor using pristine graphene doped with CuO nanoparticles

Abstract

A highly sensitive and selective NH3 gas sensor was developed based on single-layer pristine graphene doped with copper(II) oxide (CuO) nanoparticles of a specific size. High-quality single-layer graphene was grown using chemical vapor deposition. Approximately 15 nm-sized CuO colloidal nanoparticles were fabricated by a microwave-assisted thermal method using copper acetate as the precursor, and dimethylformamide as the reducing and stabilizing agent. Pristine graphene was doped with an aqueous suspension of CuO nanoparticles at a coating speed of 1500 rpm using a simple spin coater. CuO nanoparticle doping induces changes in the electronic properties of graphene; in particular, p-type doping significantly altered graphene resistivity in the presence of NH3 gas. Upon exposure of the pristine graphene surface to NH3 gas, NH3 reacted with O-2(-)/ O-/ O2- species on the graphene surface and released electrons into graphene. This caused a change in the concentration of charge carriers in the valence channel of graphene and an increase in graphene resistivity, facilitating real-time NH3 monitoring with quick response and rapid recovery at 25 celcius and similar to 55% relative humidity. Our results indicated that graphene doped with similar to 15 nm-sized CuO nanoparticles can sense NH3 gas selectively with a resistivity response of similar to 83%. Moreover, the sensor exhibited good reusability, fast response (similar to 19 s), and rapid recovery (similar to 277 s) with a detection limit of 0.041 ppm and a relative standard deviation of 0.76%.