ZnO/g-C3N4 heterostructures: Synthesis, characterization and application as photoanode in dye sensitized solar cells

Abstract

A simple low-temperature hydrothermal route was adopted to prepare the binary ZnO/g-C3N4 heterostructures, which were thoroughly characterized by various spectroscopic and microscopic probes. The clearly visible interfaces between the ZnO NRs and g-C3N4 in the HRTEM micrograph verify the formation of ZnO/g-C3N4 heterojunction structures, which, combined with N3 dye, deliver increased optical absorption extending from UV to the visible range. The binary ZnO/g-C3N4 heterostructures are used as the photoanode in the DSSC application. Improvement in the DSSC performance arises because of the growth of the g-C3N4 layer on the ZnO nanorods surface, which efficiently delays the reverse recombination of electrons from ZnO to the electrolyte. The g-C3N4 layer also increases the electron concentration in the photoelectrode and, thereby, directly contributes to the improved performance of the DSSC device. The optimal DSSC based on the ZnO/g-C3N4 photoanode delivers its characteristic JSC ∼14.18 mA/cm2, VOC ∼544 mV, FF ∼0.586 and η ∼4.52%, which is about 2.3 times greater than the DSSC efficiency based on pure ZnO nanorod photoelectrode and retains the spirit of generating the green energy following the photovoltaic endeavor.