Tribulus terrestris leaf extract assisted green synthesis and gas sensing properties of Ag-coated ZnO nanoparticles

Ag-coated ZnO nanoparticles are synthesized by a biological process using Tribulus terrestris leaf extract. The characterization results confirmed that Ag nanoparticles have been coated on the surface of ZnO nanoparticles. Ag nanoparticles on the surface of ZnO are spherical in shape, ranging between 6 and 10 nm in diameter. Gas-sensing tests reveal that all the resistance values of the sensors decrease with increasing of eathanol concentration. Moreover, the resistance of Ag-coated ZnO sensor was generally much lower than that of pure ZnO sensor. Thus, Ag nanoparticles coating paly an important role for the sensitivity of the gas sensor working at room temperature.