Enhanced photoelectrochemical performance of Ag–ZnO thin films synthesized by spray pyrolysis technique

Silver doped zinc oxide (Ag–ZnO) thin films were deposited on glass and tin doped indium oxide (ITO) coated glass substrates by using pneumatic spray pyrolysis technique (SPT) at 450 °C from aqueous solutions of zinc acetate and silver nitrate precursors. The effect of silver doping on structural, morphological and optical properties of films was studied. The XRD spectra of the Ag–ZnO films indicate the polycrystalline nature having hexagonal crystal structure. SEM micrographs show the uniform distribution of spherical grains of about 80–90 nm grain size for the pure ZnO thin films. The Ag nanoparticles are clearly visualized in SEM images of Ag–ZnO samples. The optical band gap energy decreases as the percentage of silver doping increases. Surface Plasmon Resonance (SPR) related phenomena are observed and correlated to the optical properties of Ag–ZnO thin films. The overall photoelectrochemical (PEC) performance of the samples was investigated and discussed. Moreover, the samples are more photoactive as compare to the pure ZnO sample and the sample ZnOAg₁₅ shows the highest current. The photocurrent increases upto 249 μA cm⁻² and 303 μA cm⁻² in visible light and in UV illumination, respectively, and then decreases as the Ag doping increases into the film.