Evaluation of gas-sensing properties of ZnO nanostructures electrochemically doped with Au nanophases

A one-step electrochemical method based on sacrificial anode electrolysis (SAE) was used to deposit stabilized gold nanoparticles (Au NPs) directly on the surface of nanostructured ZnO powders, previously synthesized through a sol-gel process. The effect of thermal annealing temperatures (300 and 550 degrees C) on chemical, morphological, and structural properties of pristine and Au-doped ZnO nancomposites (Au@ZnO) was investigated. Transmission and scanning electron microscopy (TEM and SEM), as well as X-ray photoelectron spectroscopy (XPS), revealed the successful deposition of nanoscale gold on the surface of spherical and rodlike ZnO nanostructures, obtained after annealing at 300 and 550 degrees C, respectively. The pristine ZnO and Au@ ZnO nanocomposites are proposed as active layer in chemiresistive gas sensors for low-cost processing. Gas-sensing measurements towards NO2 were collected at 300 degrees C, evaluating not only the Au-doping effect, but also the influence of the different ZnO nanostructures on the gassensing properties.