Effects of graphene quantum dots on microstructure, optical and gas sensing properties of coral-like ZnCo2O4 nanoparticles

In this study, the composed nanocrystalline ZnCo2O4 and graphene quantum dots (GQDs) were prepared using the facile hydrothermal method. Various microstructure characteristics were specified using X-ray diffraction analysis approaches, including Williamson-Hall and Williamson-Smallman methods. The analysis of scanning electron microscopy, Brunauer-Emmett-Teller, and atomic force microscope were used to morphological char-acteristics and the pore size distributions of samples. Besides, the optical band gap was decreased by the addition of graphene quantum dots to the ZnCo2O4 nanostructure. The greater crystallite size (45.0 nm) was accompanied by the smaller band gap (3.60 eV). The gas sensing investigations exposed that the coral-like ZnCo2O4/GQD composite nanostructures gas sensor exhibited high response (6.97-100 ppm), selectivity, and low detection limit (0.43 ppm) towards triethylamine. Moreover, enhanced gas sensing properties of coral-like ZnCo2O4/GQD composite nanostructures were observed when compared with coral-like ZnCo2O4 nanostructures. These results can be attributed to their higher pore volume and diameter than nanocrystalline ZnCo2O4.