Reduced graphene oxide and graphene composite materials for improved gas sensing at low temperature.

Reduced graphene oxide (rGO) was investigated as a material for use in chemiresistive gas sensors. The carbon nanomaterial was transferred onto a silicon wafer with interdigital gold electrodes. Spin coating turned out to be the most reliable transfer technique, resulting in consistent rGO layers of reproducible quality. Fast changes in the electrical resistance at a low operating temperature of 85 °C could be detected for the gases NO(2), CH(4) and H(2). Especially upon adsorption of NO(2) the high signal changes allowed a minimum detection of 0.3 ppm (S/N = 3). To overcome the poor selectivity, rGO was chemically functionalized with octadecylamine, or modified by doping with metal nanoparticles such as Pd and Pt, and also metal oxides such as MnO(2), and TiO(2). The different response patterns for six different materials allowed the discrimination of all of the test gases by pattern recognition based on principal component analysis.