Improvement of Heterojunction Nanomaterials Photoelectrochemical Properties by Sol-Gel Synthesis and Hydrothermal Reaction.

ABSTRACT

The ZnO nanorod arrays (NRs)/CuAlO2 laminar crystal thin films (LFs)/Ni heterojunctions with delafossite structure were prepared by sol-gel synthesis for LFs and hydrothermal for NRs. X-ray diffraction analysis demonstrates the typical delafossite structure CuAlO2 and pure ZnO of R¯3m space group. Compared with a traditional CuAlO2/Ni laminar films (LFs) nanostructure, the photocurrent of this heterojunction nanostructure is significantly increased. Note that a significant blue-shift of the absorption edge and a favorable forward current to reverse current ratio at applied voltages of -0.75 to +2 V were observed in this heterojunction with the increase of Zn2+ ion concentration in the hydrothermal reaction. Moreover, the photoelectrochemical characteristics recorded under AM 1.5 illumination with 100 mW/cm2 light intensity at 0 V (vs. Ag/AgCl), while the highest photocurrent density arrive at 3.59 mA/cm2. This study demonstrates that heterojuction nanostructure, which is easily adapted to other chemical systems, is a promising technique for improving photoelectro-chemical properties of low-cost solar cells.