Improvement of photoelectrochemical water splitting performance using photoanodes based on reduced graphene oxide and ZnO nanotubes

Abstract

Increasing the visible light efficiency, effective charge separation, and reducing the rate of charge recombination are essential factors in improving the performance of photoelectrochemical (PEC) water splitting. To enforce these, herein zinc oxide nanotube arrays hybridized with reduced graphene oxide (rGO/ZnO NTs) are synthesized on the fluorine-doped tin oxide substrates by using an electrodeposition technique for surveying PEC water splitting efficiency under visible light. The synthesized photoanodes were characterized by field emission scanning electron microscope, energy-dispersive X-ray spectroscopy, X-ray diffraction, and UV-visible absorption spectroscopy. The linear sweep voltammetry, electrochemical impedance spectroscopy, and Mott-Schottky analysis were used to evaluate the PEC performance. The rGO/ZnO NT photoanode shows a high photocurrent density of 0.441 mA/cm2 at 1.8 V vs. RHE compared to other samples. The improved PEC performance of rGO/ZnO NTs is attributed to the prominent role of rGO in more efficient charge separation, band gap reduction, and charge recombination.