Preparation And Photoelectric Properties Of Tungsten Oxide Nanomaterials

Energy is an important material basis for human survival and development,and it is the driving force for human beings’ various economic activities.Consequently,considerable efforts have been made to develop clean,green,and renewable energy-related technologies.The efficiency of these technologies depends on a variety of factors,but their overall performance strongly relies on the structure and property of the material used.Various materials have been developed,and tungsten oxides(WOx≤3)have received considerable attention due to their earth-abundance,highly tunable composition,high chemical stability under acidic conditions,and excellent electrical conductivity.The research work in this paper mainly focuses on the preparation of tungsten oxide nanomaterials and its application in the fields of supercapacitors,pollutant degradation and electrocatalytic hydrogen evolution.The main contents are as follows:(1)Through a synergistic intercalation and oxidation of FeCl3 and O2,tungsten trioxide(WO3)nanomaterials were chemically converted from layered-structure tungsten disulfide(WS2).It is found that the change of annealing temperature can control the crystal form and morphology of WO3.With the increase of annealing temperature,WO3 will change from cubic phase to monoclinic phase,and the morphology of the sample is also transformed from nanosheet structure to nanoparticles.After that,we used tungsten oxide with different crystal forms for supercapacitor studies.It was found that the cubic tungsten oxide electrode material is more excellent in cyclic voltammetry stability,constant current charge,discharge reversibility,and cycle stability.According to the analysis,the important reason for the excellent capacitance of the electrode material is inseparable from the layered morphology and the high symmetry of the crystal lattice.(2)Using a similar synthetic route,layered-structure WS2 was used as raw material to react with phosphorus pentachloride(PCl5)at high temperature to produce P-doped tungsten oxide(P-WOx)containing oxygen vacancies,which is characterized by an additional broad absorption peak between visible and near infrared region.It was also found that as the annealing temperature increases,the crystal form of the product changes with the degree of oxygen vacancies.Phosphorus doped materials with varying degrees of oxygen defects are then used in the photocatalytic degradation of the methylene blue system.The study found that samples annealed at 900 ℃ have higher degradation efficiency for methylene blue.In addition,we also use materials with a higher degree of oxygen deficiency in the electrocatalytic hydrogen evolution reaction,and initially measure the material’s intrinsic hydrogen evolution overpotential.