Thermal reduced graphene oxide-based gas sensor for rapid detection of ammonia at room temperature

Reduced graphene oxide (rGO) has attracted an enormous interest as a promising candidate for gas detection due to its large specific surface area, abundant oxygen-containing functional groups and scalable production. Although intense works have been conducted on rGO-based gas sensors, there is still much room for improvement on both their response speed and thorough exploration. In this work, thermal reduced graphene oxide (TRGO) is fabricated by spinning dilute graphene oxide (GO) suspension combined with subsequent in situ thermal reduction. TRGO sheets with size of more than 10 μm are uniformly dispersed and smoothly coated on Au interdigitated electrodes. The ammonia sensing performance indicates that 250 °C-TRGO exhibits the shortest response time of 11 s to 100-ppm ammonia. Besides, 130 °C-TRGO shows strong response to low concentration ammonia with the calculated limit of detection (LOD) of 0.9 ppm. After being exposed to air for 3 months, it still maintains 74.23% of its initial responsivity demonstrating the excellent long-term stability. Moreover, the systematic investigation on the effect of annealing temperature to the sensing performance of TRGO elaborates that with the increase in thermal reduction temperature, the responsivity monotonically decreases while the response time will decrease initially and then gradually increase after the turning point of 250 °C. These results shed a light on developing TRGO-based ammonia sensors (TBASs) for future practical applications.