The Study of Cu2ZnSnS4 Nanocrystal/TiO2 Nanorod Heterojuction Photoelectrochemical Cell for Hydrogen Generation

In this study, TiO2 nanorods arrays (TiO2 NRAs) were synthesized by hydrothermal method. The maxima current density and conversion efficiency were 2.5 mA/cm(2) at 1.23 V vs. RHE and 0.95 % with length of 6-7 mu m under AM 1.5G 1 sun condition. To improve the conversion efficiencies, Cu2ZnSnS4 (CZTS), which owns direct band gap semiconductor with 1.5 eV and suitable band positions, was employed to extend the absorption range. In this study, CZTS nanoparticles were decorated on TiO2 NRAs with adhesion layer by using solvothermal method. Finally, ZnS layer was used as passivation layer for increasing conversion efficient. By using ZnS as passivation layer, the current density increased from 2.92 mA/cm(2) to 6.91 mA/cm(2) and the conversion efficiency increased from 1.44 % to 3.50 %. According to electrochemical impedance spectroscopy (EIS) analysis, the result showed that the ZnS layer could reduce the electron-hole recombination loss to improve the conversion efficiency.