Preparation And Gas Sensing Properties Of Vanadate Iron And Bismuth Vanadate

The metal oxide semiconductor materials have become the mainstream materials for preparing gas sensor.Ternary metal oxides have be paid attention by many scientific research workers due to its unique spatial configuration and special physical and chemical properties.As a new type of multi-functional materials,vanadium-based ternary metal oxides show some unique natures and potential application values in the light,electricity,magnetic,heat and other fields in recent years.In this paper,FeVO₄ and BiVO₄ ternary metal oxides were synthesized by hydrothermal method.The films were characterized by scanning electron microscopy?SEM?,X-ray diffraction?XRD?,X-ray photoelectron spectroscopy?XPS?,Raman and nitrogen adsorption.The structure,element composition and specific surface area of FeVO₄ and BiVO₄ were analyzed.The gas sensitivity of ethanol to FeVO₄ and BiVO₄ was investigated systematically.The FeVO₄ nanoparticles with different morphology were synthesized through controlling the hydrothermal reaction temperature,the reaction time of hydrothermal reaction and the pH value of the reaction system.When the the pH was 3,the hydrothermal temperature was 160? and the reaction time was 3 hours and,the FeVO₄ sample has good crystallinity,which is a pure triclinic crystal and has a large specific surface area.The results showed that different pH have higher effect on the gas sensing performance.The FeVO₄ sample synthesized under the condition of the reaction system pH=3,has the greatest gas sensing performance.Tts optimum working temperature is 260?.The gas sensitivity to 100ppm ethanol is 3.38.The device's response to recovery performance is good.The BiVO₄ microspheres with different morphologies were synthesized by adding polyethylene glycol with different molecular weight as template and controlling the reaction temperature and reaction time.The results show that the surface of BiVO₄ microspheres is roughened and porous,and it is tetragonal BiVO₄.When the PEG 1000 is added as a template,the results of gas-sensing test show that the sensor has better gas-sensing performance.The best working temperature of gas sensor is 340?.Gas sensor sensitivity to 100 mg/L ethanol is 4.23.It has better gas-sensing performance than FeVO₄.The modification of BiVO₄ material by metal doping was carried out.The modification results of different metal doping and different doping ratios of the same metal were systematically studied.It was found that Ni,Cu,Co and Mn droping could improve sensitivity of the BiVO₄ material and the gas-sensing performance of 10%Co-doped BiVO₄ is the best.At this time,the gas sensor sensitivity of the sample can reach 11.06,and Co doping can effectively reduce the Working temperature of BiVO₄ materials and increased sensitivity and recovery response performance.