The Assembly And Photocatalytic Performance Of Oxide/Titanoniobate Nanosheets Heterojunction Materials

Photocatalytic technology is one of the effective methods to remove pollutants.Using semiconductor photocatalytic materials and photocatalytic technology to remove environmental pollutants can make full use of sunlight and achieve the purpose of environmental protection on the basis of energy conservation.Cesium titanoniobate,CsTi₂NbO₇ was successfully prepared through high temperature solid state method,and HTi₂NbO₇ nanosheet sol was obtained by acidification and exfoliation.CeO₂/HTi₂NbO₇-NS and CoO/HTi₂NbO₇-NS heterojunction composites were prepared by exfoliation-restructuring method and one-step hydrothermal method,respectively.The physical and chemical properties of photocatalysts were studied by X-ray powder diffraction?XRD?,high resolution transmission electron microscope?HRTEM?,laser Raman spectroscopy?LRS?,X-ray photoelectron spectroscopy?XPS?,UV-vis diffuse reflection spectroscopy?UV-Vis DRS?,nitrogen adsorption-desorption technology and Mott-Schottky.The photocatalytic desulfurization performance of the as-prepared samples was studied by dynamic adsorption-photocatalytic oxidation reaction with ethyl mercaptan in methane gas as model pollutant,and the corresponding photocatalytic mechanism was proposed.The results show that HTi₂NbO₇-NS has an obvious two-dimensional lamellar structure,with a specific surface area of 169.1 m²·g^-1.However,it has a large bandgap energy?3.35 eV?and is not responsive to visible light.The heterojunction composites constructed by combining HTi₂NbO₇-NS with CeO₂ and CoO still have a good two-dimensional sheet-like structure.The CeO₂ and CoO nanoparticles are evenly dispersed on the nanosheet with specific surface area of 101.2 m²·g^-1 and 115.6 m²·g^-1,respectively.Meanwhile,the band gap energy of the two heterojunction composites was significantly reduced,which was 2.61 eV and 2.23 eV,respectively,which broadened the response range of light and enabled them to respond in the visible light range,thus achieving the goal of improving the photocatalytic efficiency under the premise of making full use of sunlight.The results of dynamic adsorption-photocatalytic oxidation desulfurization showed that the adsorption capacity and conversion rate of CeO₂/HTi₂NbO₇-NS heterojunction composites of ethyl mercaptan were 708.0?mol/g and 88.77%,the adsorption capacity and conversion rate of CoO/HTi₂NbO₇-NS heterojunction composites were 340.5?mol/g and 50.46%,which were significantly better than that of nanosheet?71.0?mol/g,11.13%?,and the photocatalytic oxidation products of ethyl mercaptan adsorbed on the photocatalyst under visible light were sulfoxide and sulfonate.Photocatalytic oxidation mechanism indicates that formed type-?heterojunction between the HTi₂NbO₇-NS and oxide interface,which effectively suppresses the recombination of the electrons and holes.The separated electrons and holes can react with oxygen and water in the reaction system to generate·O₂^-and·OH with strong oxidation property,respectively,thus realizing the removal of organic sulfur compounds.Figure 36 table 8 reference 80...