In this work, WO 3 nanosheets were synthesised and decorated with different percentages of N-GO nanocomposites to study gas sensing assets. The X-ray diffraction (XRD) and Raman spectra showed fine crystal quality. Scanning electron microscope (SEM) and transmission electron microscopy (TEM) illustrated nanosheets morphology for WO3 and confirmed its decoration. The variation of the sensor electrical resistance was studied at various gas concentrations in the range of temperature intervals. The optimal operational temperature was 200 C. The optimum response signal and recovery time for WO 3 -N-GO 6% at 200 ppm concentration were 90 s and 205 s, respectively. The selectivity of the WO 3 -N-GO samples was 53%, 46% and 60% for WO 3 -N-GO 3%, WO 3 -N-GO 6% and WO 3 -N-GO 9%, respectively at 200 C. The highest response was found for WO 3 -N-GO 9% to NO 2 (58%) and WO 3 -N-GO 6% to CO (28%) at 200 C. Therefore, by selecting the optimum percentage of N-GO nanocomposites, the sensors can be fabricated with the highest response to NO 2 or CO.

In this research, tungsten trioxide (WO 3) nanoplates and WO 3 /N-doped reduced graphene oxide (WO 3 /N-rGO) nanocomposites were synthesized with various amounts of N-rGO using the hydrothermal method. X-ray diffraction analysis showed that WO 3 /N-rGO nanocomposites (with 3%, 6%, and 9% of N-rGO) had a hexagonal structure with (200) preferential radial of the crystal plane. According to transmission electron microscopy images, WO 3 has a nanoplate structure with a width within the range of 20-40 nm and length of 500 nm. The result of bandgap energy calculation was 3.69 eV for WO 3 , while for WO 3 /N-rGO 3%, WO 3 /N-rGO 6%, and WO 3 /N-rGO 9%, it was 2.65 eV, 2.84 eV, and 2.61 eV, respectively. Dynamic light scattering confirmed particle sizes 86.7 nm, 56.9 nm, and 76.9 nm for the samples with 3%, 6%, and 9% N-rGO, respectively. The minimum of particle size was for WO 3 /N-rGO nanocomposites. Photoluminescence spectra revealed that there were a few transitions in which the intensity in WO 3 /N-rGO 3% was stronger than in the samples with 6% and 9% N-rGO. The origin of these emissions is associated with oxygen vacancies, defects, near-band edge transition, and band-to-band transition. The effective control of bandgap has a clear advantage for use in optical devices and makes the samples more applicable in electrical, photo-electrochemical, and photocatalytic applications.