Since the photo electrochemical cell was used in the conversion of the solar energy to the electrical power or to hydrogen

more and more attention has been paid in this field. The photocathode plays an important roll in the electrochemical chain of PEC. In this paper

the p-n junction was used to improve efficiency of the photocathode because the inner electric field of the p-n junction can make the photo-generated carriers separate more easily. The NiO electrode and the NiO-TiO

2

hybrid electrode were fabricated on the SnO

2

:F (FTO) transparent conducting glass via sol-gel method. The solution was prepared by using the nickel acetate tetra hydrate and the tetra-n-butyl tianate as precursors. The films were obtained by spin-coating method and then annealed at 450℃ in air for three hours. The crystal structures of the films were characterized by X-ray diffraction (XRD). Scanning electron microscopy (SEM) was also used to investigate the microstructures of the films. The XRD results showed that all the strongest peaks were indexed to the anatase TiO

2

and the bunsenite NiO

respectively. From SEM

the surface of the film was quite compact

the grains were nanometer-sized and the thicknesses of NiO and TiO

2

layer were 200nm and 130nm

respectively. Moreover

the photoelectrochemical properties of the NiO and the NiO-TiO

2

hybrid electrode were also investigated under 500W Xe arc lamp illumination. It was found that the cathode photocurrent of the NiO-TiO

2

hybrid electrode was larger than that of the NiO electrode and that the flat-band potential of the hybrid electrode was also more positive than that of NiO electrode. Therefore

the results indicated that the photo-generated carriers could be separated and transferred more easily for the build-in electric field of the p-n junction. Besides

an energy band diagram of the p-n junction was proposed to explain the results in this paper.