Estudo do efeito da prata nas propriedades do óxido de zinco

Abstract

The incorporation of different ions and metals in the oxide lattice, as well as, the control of synthesis parameters as pH, reaction time, temperature and used precursors are efficient strategies to increase and control semiconductor properties. In this work, it was investigated the effect of different amounts of metallic silver (Ag) (2,0, 4,0 and 8,0 mol% Ag) as well as the reaction time (2 and 8 minutes) in the structural properties of zinc oxide (ZnO) and the obtained ZnO/Ag nanocomposites, demonstrating the influence of these parameters in the oxide structural organization. These materials were obtained under microwave-hydrothermal conditions, a simple and ecological method that offers advantages such as fast and homogeneous heating. The X-ray diffractograms of pure ZnO samples confirmed the formation of a single crystalline phase corresponding to the wurtzite structure of ZnO and ZnO/Ag samples obtained in 8 minutes of synthesis showed additional peaks related to the cubic phase of Ag in the oxide lattice. The Raman spectra of the samples showed characteristic peaks of the wurtzite ZnO structure and a decrease in intensity of these peaks in the silver samples. SEM images revealed clusters of nanostructures with irregular sizes and shapes. Experiments on the electrochemical reduction of CO2 to carbon monoxide demonstrated the selectivity of the samples for CO formation and the improvement in the electrical properties due to the presence of silver, exhibiting promising current density values, and ZnO/8% Ag sample obtained in 8 minutes demonstrated most promising results.