Electrical Transport Properties And Negative Photoconductivity Of H-WO₃ Nanowire

WO₃ has the peculiar electronic band structure.The electric potential energy of the holes at the top of the WO₃ valence band is larger than the oxidation potential energy of water,and the electric potential energy of electrons at the bottom of the WO₃ conduction band is less than the reduction potential energy of water.Therefore,under the illumination or bias,water molecules adsorbed on the surface of WO₃ can be oxidized to produce H⁺ions and O₂ by holes at the top of the valence band,while H⁺ ions cannot be reduced to produce H₂ by electrons at the bottom of the conduction band.H⁺ ions can absorb on the surface of the WO₃ or embed in the lattice of the WO₃,which not only enriches the chromic properties and resistance properties of WO₃,but also affects its photoelectric properties significantly.The negative photoconductivity of the WO₃ has been observed in a high humidity environment,which might be attributed to the accumulation of H⁺ions on the surface of the WO₃.The single crystal h-WO₃ nanowire has large specific surface area and internal pores,which is an ideal platform to study the physical mechanism of negative photoconductivity of the WO₃ and the effect of H⁺ ions on its electrical transport properties.In this paper,the main results are as follows:1.First,the h-WO₃ nanowires with the appropriate length and diameter were prepared by hydrothermal method.Then,the Au/h-WO₃NW/Au based on the h-WO₃ nanowire was constructed by deep ultraviolet lithography,coating technology and stripping technology.2.We systematically investigated the electrical transport properties of h-WO₃ nanowire based on the Au/h-WO₃ NW/Au.First,the oxygen vacancy was verified to play an important role in the memristive properties of h-WO₃ NWs.Then,the effect of H⁺ on the surface of nanowires and embedded in the crystal lattice was explored separately.3.First,the physical mechanism of the negative photoconductivity ofh-WO₃nanowirewasexplored.Then,thecreation,distribution and annihilation of H⁺ ions on the surface of WO₃ are manipulated by adjusting the relative humidity,light intensity or bias voltage,thereby realizing the conversion of positive and negative photoconductivity.