Influence of seeding layer on photoelectrochemical hydrogen production over TiO2 nanorod decorated with reduced graphene oxide

Abstract

A seeded TiO2 nanorod decorated with reduced graphene oxide (rGO) was synthesized to improve solar hydrogen production performance in a photoelectrochemical cell. The rutile TiO2 nanorod was grown on the surface of the screen-printed anatase TiO2/fluorine-doped tin oxide (FTO) substrate via hydrothermal technique and then rGO was deposited on the surface of seeded TiO2 nanorod by spin-coating and thermal treatment. The photocatalytic activities are evaluated in terms of hydrogen production and photoelectrochemical properties. X-ray diffractometer and transmission electron microscopy show the presence of anatase and rutile TiO2 with different lattice fringes and rGO on the surface of the photocatalyst. Field-emission scanning electron microscopy reveals that introducing seed layer increased the density of the nanorod and its active surface area. X-Ray photoelectron spectroscopy (XPS) and Raman spectra confirmed a strong interaction between TiO2 and rGO, leading to better charge carrier transfers and reduce their recombination rate. The photocurrent density of seeded TiO2 nanorod@ rGO was higher than rutile or anatase TiO2@ rGO due to low charge transfer resistance and long electron lifetime. The seeded TiO2 nanorod@ rGO composites produced a maximum accumulative hydrogen of 1200 mmol/cm2 in a mixture of 1 M KOH and 5 vol% glycerol in the photoelectrochemical cell under visible light irradiation compared with rutile or anatase TiO2@rGO. It is believed that this predominant photocatalytic activity is due to the synergistic contribution of direct electron transport between anatase and rutile TiO2 phases, a high electron mobility of rGO and an increased surface area originated from TiO2 nanorod.