ZnO/Cu2O-decorated rGO: Heterojunction photoelectrode with improved solar water splitting performance

Abstract

In present work, we report a facile fabrication process to improve the photoelectrochemical (PEC) performance of ZnO-based photoelectrodes. In order to achieve that, the Cu2O nanocubes are cathodic-deposited on the as-prepared ZnO nanorods. Then rGO nanosheets are electrodeposited on the ZnO/Cu2O heterostructures. The fabricated photoelectrodes are systematically studied in detail by different characterization techniques such as powder X-ray diffraction, micro-Raman, X-ray photoelectron spectroscopy, ultraviolet diffused reflectance spectroscopy and photoluminescence spectroscopy analysis. Morphologies of the fabricated photoelectrodes are investigated through electron microscopy in scanning and transmission mode. To evaluate the PEC performance of the fabricated photoelectrodes, the line scan voltammetry (LSV) measurement is performed using a three-electrode system in 0.5-M Na2SO4 electrolyte solution under stimulated light illumination at 100 mW/cm2 from a 300-W Xenon Arc lamp coupled with an AM 1.5G filter using a three-electrode system. The photocurrent measurement demonstrates that the photoelectrodes based on ZnO/Cu2O/rGO possess enhanced PEC performance compared to the pristine ZnO and ZnO/Cu2O photoelectrodes. The photocurrent density of ZnO/Cu2O/rGO-15 photoelectrode (10.11 mA/cm2) is ∼9 and ∼3 times higher than the photoelectrodes based on pristine ZnO (1.06 mA/cm2) and ZnO/Cu2O (3.22 mA/cm2). The enhanced PEC performance of ZnO/Cu2O/rGO photoelectrode is attributed to the excellent light absorption properties of Cu2O and excellent catalytic and charge transport properties of rGO. Experimental results reveal that the proposed functional nanomaterials have a great potential in water splitting applications.