In the present work, mesoporous ZnO/reduced graphene oxide (rGO) nanocomposites were successfully synthesized using a facile and environment-friendly hydrothermal method. The ZnO/rGO nanocomposites were characterized through a broad range of characterization techniques such as X-ray diffraction, field emission scanning electron microscopy, energy dispersive X-ray spectroscopy, X-ray photoelectron spectroscopy, Brunauer–Emmett–Teller analysis, Raman and photoluminescence spectroscopy. ZnO/rGO nanocomposites exhibited enhanced photocatalytic activity towards decomposing methylene blue (MB) dye under a low-power ultraviolet light (8 W). In these conditions an almost complete removal of dye (99.66%) was achieved within 100 min for the sample with more value of GO (compared to 78.36% for pure ZnO). We also explored the use of ZnO/rGO nanocomposites deposited on gold electrodes for the fabrication of ethanol vapor sensors. An excellent sensing ability was observed in its high response for the selected sample (110.11 toward 100 ppm ethanol vapor in comparison with 14.54 for pristine ZnO), very low response/recovery time (below 4 s), good selectivity and ultralow estimated detection limit of about 27 ppb which makes it a prospective use in gas sensors. As a result of the overall analysis, the formation of ZnO/ rGO nanocomposite can considerably improve the photocatalytic and gas sensing properties of ZnO and thus can be used for various applications such as environmental considerations.
