Bimetallic Au/Pd nanoparticles decorated ZnO nanowires for NO2 detection

Various mono-noble metal nanoparticles (NPs) have been used to improve the functionalities of semiconducting sensing materials for high-performance gas sensors. However, understanding the effect of bimetallic noble NPs on their gas sensing behaviors is limited. In this work, the bimetallic Au/Pd-NPs decorated ZnO nanowires (ZNWs) were fabricated to study their NO2 sensing performance through comparing with their counterparts of pristine ZNWs, and mono Au- or Pd-NPs decorated ZNWs. The bimetallic Au/Pd-NPs decorated ZNWs were prepared by dipping the pristine ZNWs in a mixed solution of HAuCl4, PdCl2, Na2CO3, and absolute ethanol with heating evaporation. The bimetallic Au/Pd-NPs decorated ZNWs exhibited higher response of 94.2, faster response/recovery time of 35 s / 30 s, and lower optimal operating temperature at 100 degrees C towards 1 ppm NO2 than the performance of pristine ZNWs and mono Au- or Pd-NPs decorated ZNWs. Meanwhile, good selectivity and reproducibility have been achieved by bimetallic Au/Pd-NPs decoration. The mechanism on the enhanced sensing performance of the bimetallic Au/Pd-NPs decorated ZNWs has also been investigated systematically.