Effect of Cu, Ni and Pb doping on the photo-electrochemical activity of ZnO thin films

In the present study, the effects of metallic doping on the photoelectron\chemical properties of zinc oxide thin films have been studied. All films have been deposited using the spray pyrolysis technique at a constant doping level of 3 wt% whereby Cu, Ni, and Pb were used as dopants. The structure of all films was studied by X-ray diffraction which showed the grain size of all doped films to be 50 nm. The energy band gap of all films was estimated using optical transmission spectroscopy. The Ni, Cu, and Pb-doped ZnO photoelectrodes were applied for the photoelectrochemical (PEC) H₂ generation from H₂O. Pb doping leads to the highest photocurrent of the ZnO photoelectrodes. The current density-potential characteristics were measured under white light and monochromatic illumination. The stability of the electrode was quantified as a function of the number of H₂ production runs and exposure time. Finally, the incident photon-to-current conversion efficiency, IPCE, and applied bias photon-to-current efficiency, ABPE, were calculated. The optimum IPCE at 390 nm was ∼30% whereas the ABPE was 0.636 at 0.5 V.