Ni-Doped Cu2O Thin Films for Solar-Hydrogen Generation: Experiments and First-Principles Analysis

Nanostructured thin films of undoped and Ni-doped Cu2O on ITO glass substrate were deposited using spray pyrolysis method for their use as photocathode in photoelectrochemical water splitting. In order to understand the effect of Ni substitution on photoelectrochemical performance of Cu2O a combination of both experiments and first-principles density functional theory based calculations were done. All samples were characterized using XRD, SEM and UV-Vis spectrometry. Photoelectrochemical properties were also undertaken in a three-electrode cell system. The results of DFT calculations show the minimal changes appear in the band gap and band gap energies in the Ni-doped Cu2O system, keeping it still a direct band gap material. A defect band appearance can be seen near the Fermi level mainly of Ni 3d offering improved conductivity and fourfold increase in photocurrent density with respect to undoped samples. Experimental verification of the proposed mechanism for improved photocurrent density using DFT calculations of Ni doped Cu2O is the innovative aspect of the present study.