In this study, ZnO/Ag nanocomposites were synthesized using a facile chemical route involving metallic precursors of zinc acetate dehydrate and silver acetate, and dissolving the two metallic precursors in EtOH. The final concentration of the solution was 0.4 M. The different nanocomposites were synthesized using different atomic percentages of silver to compare the amount of silver nanoparticles with the bactericidal power of the nanocomposites. They were prepared at concentrations of 0, 1, 3, 5, 7, and 10 at%. The as-prepared nanocomposites were characterized using X-ray diffraction (XRD), scanning electron microscopy (SEM) and scanning transmission electron microscopy (STEM) to study their structural and morphological properties. SEM showed that there is a clear effect of Ag on the size of the ZnO particles, since when silver percentages of 1 at% are included, the grain size obtained is much smaller than that of the ZnO synthesis. The effect is maintained for 3, 5, 7, and 10 at% silver. Transmission electron microscopy (TEM) compositional mapping confirms the presence of spherical nanoparticles in the synthesized samples. The size of the nanoparticles ranges from about 10 to about 30 nm. In addition, UV-Vis and Raman spectroscopy were performed to obtain structural details. The different samples show an increase in the absorption in the visible range due to the incorporation of the silver NPs. Measurement of the antimicrobial activity was tested against Staphylococcus aureus (S. aureus) and Escherichia coli (E. coli) It is shown that zinc oxide has bactericidal power for these two groups of bacteria and also that when it is used together with silver NP, this effect improves, eliminating more than 90% of inoculated bacteria.

Doped ZnO are among the most attractive transparent conductive oxides for solar cells because they are relatively cheap, can be textured for light trapping, and readily produced for large-scale coatings. Here, we focus on the development of alternative Na and K-doped ZnO prepared by an easy low-cost spray pyrolysis method for conducting oxide application. To enhance the electrical properties of zinc oxide, alkali-doped Zn_1−x M_xO (x = 0.03) solid solutions were investigated. The resulting layers crystallize in a single hexagonal phase of wurtzite structure with preferred c-axis orientation along a (002) crystal plane. Dense, well attached to the substrate, homogeneous and highly transparent layers were obtained with great optical transmittance higher than 80%. The optical energy band gap of doped ZnO films increase from 3.27 to 3.29 eV by doping with Na and K, respectively. The electrical resistivity of the undoped ZnO could be decreased from 1.03 × 10⁻¹ Ω.cm to 5.64 × 10⁻² Ω.cm (K-doped) and 3.18 × 10⁻² (Na-doped), respectively. Lastly, the carrier concentrations increased from 5.17 × 10¹⁷ (undoped ZnO) to 1 × 10¹⁸ (doped ZnO).

ZnO thin films with oxygen vacancies and doped with Al, Ga, and In (Zn_1-xM_xO_1−y (x = 0.03)) have been successfully deposited on soda-lime glass substrates using a simple soft chemical method. The crystalline structure shows a single hexagonal phase of wurtzite with preferred crystal growth along the 002 plane. The surface morphology, characterized by SEM, revealed that the grain shape varies depending on the dopant agent used. Optical measurements displayed an increase in the bandgap values for doped films from 3.29 for ZnO to 3.35, 3.32, and 3.36 for Al, Ga, and In doped films, respectively, and an average transmittance superior to 90% in some cases (in the range between 400 and 800 nm). The electrical response of the films was evaluated with a four-point probe being 229.69, 385.71, and 146.94 Ω/sq for aluminium, gallium, and indium doped films, respectively.

The upcoming chapter explores zinc oxide (ZnO) thin films, examining their crystalline and optical properties. It discusses various deposition techniques for creating thin films, defined as layers from nanometers to micrometers thick, used in electronics, optics, and coatings. Thin film deposition methods, crucial for controlling film thickness and properties, include physical vapor deposition (PVD), sputtering, thermal evaporation, electron beam evaporation, and pulsed laser deposition (PLD). These techniques are vital in electronics, optics, and materials research. The chapter also covers ZnO thin films’ applications, emphasizing their photocatalytic abilities. ZnO has a large bandgap energy (3.37 eV), making it effective in UV light absorption and photocatalytic reactions. Upon UV photon absorption, ZnO generates electron-hole pairs, leading to efficient redox processes. ZnO’s chemical stability ensures lasting photocatalytic activity, resisting degradation under harsh conditions. It can be formed into nanostructures like nanoparticles, nanowires, and nanosheets, increasing surface area and catalytic efficiency. ZnO generates reactive oxygen species (ROS) like hydroxyl radicals, superoxide radicals, and hydrogen peroxide during photocatalysis. These ROS degrade organic pollutants, functionalizing substrates to break down fertilizers, pesticides, pharmaceuticals, nitrates, and pollutant gases such as nitrogen oxides and benzene compounds.