Study On Preparation And Properties Of Transition Metal Cobalt Modified Brookite TiO₂

TiO₂ is a kind of excellent photocatalytic material.But plate brookite TiO₂ wide forbidden band width?about 3.1 to 3.1 eV?,the low utilization ratio of visible light and the low quantum efficiency of faults,which lead to low brookite TiO₂photocatalytic activity,limit its practical application.The photocatalytic activity of brookite TiO₂ can be greatly improved by modifying the brookite TiO₂,which not only broadens the visible light absorption range,but also suppresses the recombination of photogenerated electrons and photogenerated holes.In this study,Co-doped brookite titanium dioxide?Co-TiO₂?photocatalysts were synthesized via the hydrothermal method with titanium tetrachloride as raw materials and cobalt chloride hexahydrate as dopant.The prepared Co-TiO₂photocatalysts were characterized by X-ray diffraction?XRD?,Scanning electron microscopy?SEM?,transmission electron microscopy?TEM?,Raman spectroscopy?Raman?,X-ray photoelectron spectroscopy?XPS?,UV–Vis diffuse reflectance spectroscopy?UV–Vis DRS?,and so on.Isopropanol?IPA?was a kind of typical volatile organic compounds?VOCs?,the photocatalytic activity of Co-TiO₂ photocatalysts was evaluated by photocatalytic degradation of IPA under the condition of visible light.The influences of different doping rates of Co,IPA gas initial concentrationand photocatalyst addition were also studied.At the same time,the photocatalytic mechanism of these samples was also explored.In addition,the photocatalytic performance of Co-TiO₂ photocatalyst was tested by electrochemical workstation.The doping of transition metal Co could impacts the phase composition of TiO₂.When the doping amount of Co is less than 10%,the product is the pure brookite TiO₂phase.When the doping amount of Co is more than 10%,the product has both brookite and anatase phase.The doping of Co could decrease the size of brookite TiO₂particle.This can be ascribed to the doping of Co or cobalt compound in TiO₂ crystal could supress the increasing of TiO₂ grain,size of the Co-TiO₂ photocatalyst particle is decreased.Thus the specific surface area became larger with the increase doping amount of Co.In addition,the band gap of Co-TiO₂ photocatalyst decrease significantly,the absorption pectrum could red shift to the visible light region.This is beneficial to the improvement of the photocatalyst activity.Furthermore,different Co doping amount,IPA initial concentration and addition of Co-TiO₂ photocatalyst have different photocatalyst activity.The photocatalytic performance of Co-TiO₂photocatalyst could up to 91%,when the doping amount of Co is 7%,the initial concentration of IPA is 1.0×10^-6 mol/L,and the addition amount of Co-TiO₂photocatalyst is 50 mg.