The role of gold catalyst on the sensing behavior of ZnO nanorods for CO and NO2 gases

TLDR: A facile one-pot strategy was developed for the assembly of gold nanoparticles (Au NPs) onto single crystalline ZnO nanorods using cetyltrimethylammonium bromide (CTAB) as a capping agent.

Abstract: A facile one-pot strategy was developed for the assembly of gold nanoparticles (Au NPs) onto single crystalline ZnO nanorods using cetyltrimethylammonium bromide (CTAB) as a capping agent. Zinc oxide nanorods were synthesized by hydrothermal method whereas the Au NPs (below 5 nm) were deposited on the surface of ZnO nanorods by the solution growth method. Gas sensing properties of Au/ZnO nanorods were studied at various temperatures for various concentrations of reducing (CO) and oxidizing (NO 2 ) gases in synthetic air and compared with pristine ZnO nanorods. Sensor fabricated by Au/ZnO nanorods showed significantly enhanced sensing performances for CO gas while opposite was the case with NO 2 gas as compared to pristine ZnO nanorods. The highest response of Au/ZnO nanorods for CO gas was 12 at 150 °C while for ZnO nanorods, it was 6.12 at 400 °C. Whereas the highest response of Au/ZnO nanorods for NO 2 gas was 4.14 while for ZnO nanorods, it was 10 at 300 °C. It was found that Au NPs acted as promoter for CO gas while inhibiter for NO 2 gas sensing due to their different sensing mechanisms. This study suggested that noble metals decoration of ZnO nanorods can be used for selectivity issue between CO and NO 2 gases.