Highly porous ZnO modified with photochemical deposition of silver nanostructure for ultra-sensitive triethylamine detection

Doping noble metals into semiconductor based gas sensors was proved to be an effective strategy in improving gas response properties. Here, we report a silver/silver (II) oxide nanoparticles (Ag/AgO NPs) modified highly porous ZnO nanocomposite. Firstly, the Ag NPs were evenly deposited on the surface of flower-like ZnCO3 precursors through a simple photochemical reduction method, which was then heated at 400 °C to give highly porous Ag/AgO/ZnO nanocomposite, accompaning with the dissociation of ZnCO3 after release of CO2. The interleaving ultrathin and porous sheet-like features of Ag/AgO/ZnO nanocomposite afford it excellent triethylamine (TEA) sensing performance with Ra/Rg = 90.3 at an operating temperature of 240 °C, and the response sensitivity is 5.5-fold higher than that of pure ZnO. Specifically, the porous Ag/AgO/ZnO nanocomposite exhibited a fast response/recovery time of 53 s/8 s and oustanding long-term cyclic stability. The enhanced gas sensing performance can be attributed to the sensitization of Ag/AgO NPs, significantly increasing the number of oxygen vacancies and thus providing more reactive sites. The synergistic interaction between Ag/AgO NPs and porous ZnO nanosheets also facilitates a fast electron transport and a high permeability for gas molecules. This work displays a feasible way of coupling photochemical reduction and pyrolysis strategy to develop highly porous ZnO nanosheets functionalized by noble metal NPs with remarkably enhanced gas response property.