The Influence Of Graphene Loading On The Photoelectrochemical Properties Of One Dimensional TiO₂ And MoO₃-TiO₂ Nanotubes

With the development of economy and society, resources and environment have become the major problems restricting the development of human society. As a way to use solar energy to degrade organic pollutants and to produce H2 by water splitting,photocatalysis has become a hot topic of scientists around the world. As a traditional photocatalyst, Ti O2 has promising applications in many fields, such as water purification,gas sensors, photovoltaic and photocatalytic hydrogen production, etc. However, the band gap of Ti O2 is so wide that it can only account for 5% of sunlight energy ultraviolet light and the recombination of photo-generated electron-hole pairs are easy,resulting in the lower quantum yield in the conversion of solar energy. The abovementioned challenges serve as the impetus to engineer an environmentally benign and adsorptive solar photocatalytic material by modifying the surface structure of Ti O2.In this paper, we modify the Ti O2 in two aspects by improving the electrochemical properties of semiconductor materials and reducing the band gap. We selected graphene and Mo O3 as the modification materials to improve the properties of Ti O2.The following are the main points of the paper.The graphene oxide loaded one-dimensional Ti O2 nanotubes was prepared by anodic oxidation method. The reduction of graphene oxide to graphene is conducted by ultraviolet irradiation method. We change graphene oxide loading amount by regulating the anodizing electrolyte concentrations which is optimized by the electrochemical properties of the composites measured by the cyclic voltammetry and electrochemical impedance.The results show that nanotubes prepared by electrolyte containing 0.3mg /m L graphene oxide shows the electrochemical properties.The one-dimensional Mo O3-Ti O2 nanotube composites are synthesized by anodic oxidation on the Ti-Mo alloy(Mo mass percentage is 7%) substrate.The polymorph,morphology and composition were characterized by XRD, SEM, XPS separately. The electrochemical anodic oxidation voltage, heat treatment temperature and other conditions were optimized. Surface photovoltage and photocurrent measurement are used to assess the photoelectrochemical properties of Mo O3-Ti O2 nanotubes. Finally,the photocatalytic hydrogen production of Mo O3-Ti O2 were evaluated by water splitting performance tests. It was found that the anodic oxidation voltage at 50 V, 650 ℃annealed Mo O3-Ti O2 nanotubes show better electrochemical properties and photoelectrochemical water splitting performances than the Ti O2 nanotubes prepared under the same condition.Graphene was loaded on the Mo O3-Ti O2 nanotubes for modification of the materials.The immersion and anodic oxidation methods were applied to prepare thenanocomposites.After electrochemical tests, we found that Mo O3 and graphene oxide have a synergistic effect which can furtherly improve the electrochemical properties of Ti O2 nanotubes.