Ultrasensitive formaldehyde gas sensor based on Au-loaded ZnO nanorod arrays at low temperature

Au-loaded ZnO nanorod arrays sensor exhibits high response, short response and recover times, excellent selectivity, as well as low HCHO detection limit at 70 °C. Moreover, the mechanism of HCHO sensing with Au-loaded ZnO was explored by the calculations obtained from the first-principle studies. The outstanding sensing properties could be ascribed to large surface area and good gas diffusion of the nanorods arrays, Au spillover mechanism, as well as high contents of chemisorbed oxygen on the its surface derived from electrons transfer from Au to ZnO. [Display omitted] •Au/ZnO nanorod arrays are synthesized via seed-assisted solvothermal methods.•Au/ZnO sensor shows excellent response to HCHO at 70 °C.•The mechanism of HCHO sensing with Au/ZnO is explored by the calculations obtained from the first-principle studies. Au-loaded ZnO were successfully prepared by means of seed-assisted solvothermal methods. The vertically ordered nanorod arrays are uniformly grown on the Al2O3 substrate. The sensing properties of ZnO and Au-loaded ZnO sensors toward HCHO were investigated. Remarkably, the sensor based on 4 wt%Au-loaded ZnO nanorod arrays exhibits high response, short response and recover times, excellent selectivity, as well as low HCHO detection limit at 70 °C. After the incorporation of Au nanoparticle, the detection limit decreases from 10 ppm to 0.25 ppm, and the response increases more than 20 times under 100 ppm HCHO at 70 °C. Moreover, the mechanism of HCHO sensing with Au-loaded ZnO was explored by the calculations obtained from the first-principle studies.