Study On The Preparation And Photocatalytic Properties Of Nanosized Tantalum Composite Oxide Photocatalytic Materials

Nanosized tantalum composite oxide photocatalytic materials have extensiveapplication prospects in the field of photocatalytic decomposition of water hydrogendue to their superiority in photocatalytic performance. Moreover, the photocatalyticproperties can be improved by loading noble metals and doping metal ions. In thispaper, Na₂Ta₂O₆nanotube arrays, Na₂Ta₂O₆hollow spheres and Au/In₂O₃/Ta₂O₅nanosized composite photocatalysts were prepared by anodic oxidation andhydrothermal method. Pt and Au were loaded on the Na₂Ta₂O₆nanotube arrays andIn₂O₃/Ta₂O₅nanosized composite photocatalysts, respectively, which can improve thehydrogen production rate. The morphologies, crystal structures and compositions ofthe prepared catalysts were characterized by SEM, XRD, XPS, EDS and UV-Vis DRSanalysis, and the photocatalytic activities of the prepared catalysts were tested byphotocatalytic hydrogen evolution from water splitting.First, Ta₂O₅nanotube array films were prepared by anodization of Ta foil indifferent composition of electrolyte. When Ta₂O₅nanotube arrays were prepared in3%HF,8%H₂O and H₂SO4electrolyte by anodization for20min, the samples haveregular morphology, ordered array and uniform diameter. Then Na₂Ta₂O₆nanotubearrays were successfully synthesized by hydrothermal treatment of Ta₂O₅nanotubearrays in Na2CO3for2h. The prepared Na₂Ta₂O₆nanotube array thin films showedhigh photocatalytic activities for water splitting, depending on the concentration ofNa2CO3and reaction time.In order to improve the photocatalytic activities of Na₂Ta₂O₆nanotube arrays,metal Pt was loaded on the Na₂Ta₂O₆nanotube array thin films by photochemicalreduction method. XPS analysis shows that Pt exists in a form of metal on the Na₂Ta₂O₆nanotube arrays thin films. The effects of loading Pt and the amount of Pt on thephotocatalytic water splitting for hydrogen production were studied. When the amountof Pt loading is2μmol, the hydrogen production rate is the highest. Moreover, the cyclestability of Pt/Na₂Ta₂O₆nanotube array thin film was studied. The result shows that thephotocataltic property for water splitting over Pt/Na₂Ta₂O₆nanotube array thin film is very stable.Secondly, Na₂Ta₂O₆hollow spheres were prepared by hydrothermal method in NaFsolution. The morphology of the sample is entirely spherical when the concentration ofNaF is lower. With the increase of the concentration of NaF, the sample has obvioushollow sphere structure. XRD analysis shows that Na₂Ta₂O₆hollow spheres with cubicpyrochlore were formed by hydrothermal method.Finally, In₂O₃/Ta₂O₅nanosized composite photocatalysts in different molar ratio ofTa and In were prepared by hydrothermal method. The morphology of the preparedsample is composed of nanorod and nanoparticle structures. Nanorods get together toform tufted structue with the increase of In molar ratio. Meanwhile, metal Au wasloaded on the In₂O₃/Ta₂O₅nanosized composite photocatalysts. And the photocatalyticactivities of Au/In₂O₃/Ta₂O₅nanosized composite photocatalysts were tested byphotocatalytic hydrogen evolution from water splitting. The result shows thatAu/In₂O₃/Ta₂O₅nanosized composite photocatalysts have obvious photocatalyticactivity under visible light. Moreover, the mechanism of semiconductor photocatalyticwater splitting for hydrogen production was discussed.