Hydrothermal Synthesis and Improved CHOH-Sensing Performance of ZnO Nanorods With Adsorbed Au NPs

The high-density and well-aligned zinc oxide (ZnO) nanostructures with adsorbed gold (Au) nanoparticles (NPs) grown on indium-tin-oxide (ITO) glass substrates were used as a gas-sensing material. The Au NPs-adsorbed nanorod (NR) arrays were successfully grown on the substrates via the simple hydrothermal method at various Au NP sputter deposition times (0 and 30 s). The crystal characteristics, surface morphologies, and elemental distributions were studied by using the X-ray diffraction (XRD) spectrometry, the field-emission scanning electron microscopy (FE-SEM), and the high-resolution transmission electron microscopy (HR-TEM) with an energy dispersive X-ray (EDX) elemental mapping analysis, respectively. The NR structures were vertical to the substrate surface with hexagonal wurtzite structure and single-crystalline performance. All sensors were prepared in a self-made chamber, indicating that the response of the sample toward methanol (CH3OH) vapor at different working temperatures was enhanced by Au adsorption. Additionally, the sensor showed a remarkably enhanced response (62.65%) to 1000 ppm CH3OH at the optimal operating temperature of 150 degrees C. Simultaneously, the sensor evidently displayed stable and repeatable behavior, and selectivity toward the CH3OH vapor with no substantial response to isopropyl alcohol, acetone, and ethanol vapors. The designed sensor in this investigation may detect harmful gas in the Internet of Thing applications.

Automated summary

In this study, high-density and well-aligned zinc oxide nanostructures with adsorbed gold nanoparticles were used as a gas-sensing material, showing enhanced response to methanol vapor at different working temperatures. The sensor exhibited stable and repeatable behavior, with selectivity towards methanol vapor and no substantial response to other vapors such as isopropyl alcohol, acetone, and ethanol. The designed sensor has the potential for detecting harmful gases in IoT applications.