Hydroxyl edge-functionalized graphene quantum dots for gas-sensing applications

In this work, an alternative room-temperature gas sensor was fabricated by drop-casting hydroxyl-functionalized graphene quantum dots (OH-GQDs) onto an interdigitated nickel electrode. The OH-GQDs were prepared based on a bottom-up approach using the hydrothermal treatment of pyrene. Physicochemical characterizations based on the FE-TEM, UV-vis, Raman and XPS confirmed the successful formation of OH-GQDs with high homogeneity and purity. The gas-sensing mechanism of OH-GQDs gas sensor was systematically investigated via gas-sensing experiments and self-consistent charge density functional tight-binding (SCC-DFTB) calculations. The results showed that the room-temperature OH-GQDs gas sensor owns high sensitivity and selectivity as well as fast response to ammonia (NH3) with linear relationship at the concentration ranging from 10 to 500 ppm. The SCC-DFTB calculations indicated that the OH functional group was a major contributing factor to the NH3 sensitivity and selectivity. This study revealed that the modification of GQDs via edge functionalization is a promising approach to attain high performance gas sensors with high selectivity to a desired target gas.