Abstract
Flower-like titanium dioxide (TiO2) nanostructures are successfully synthesized using a hybrid sol-gel and a simple hydrothermal method. The sample was characterized using various techniques to study their physicochemical properties and was tested as a photocatalyst for methyl orange degradation and as an antibacterial material. Raman spectrum and X-ray diffraction (XRD) pattern show that the phase structure of the synthesized TiO2 is anatase with 80-100 nm in diameter and 150–200 nm in length of flower-like nanostructures as proved by field emission scanning electron microscope (FESEM). The energy-dispersive X-ray spectroscopy (EDS) analysis of flower-like anatase TiO2 nanostructure found that only titanium and oxygen elements are present in the sample. The anatase phase was confirmed further by a high-resolution transmission electron microscope (HRTEM) and selected area electron diffraction (SAED) pattern analysis. The Brunauer-Emmett-Teller (BET) result shows that the sample had a large surface area (108.24 m2/g) and large band gap energy (3.26 eV) due to their nanosize. X-ray photoelectron spectroscopy (XPS) analysis revealed the formation of Ti4+ and Ti3+ species which could prevent the recombination of the photogenerated electron, thus increased the electron transportation and photocatalytic activity of flower-like anatase TiO2 nanostructure to degrade the methyl orange (83.03%) in a short time (60 minutes). These properties also support the good performance of flower-like titanium dioxide (TiO2) nanostructure as an antibacterial material which is comparable with penicillin which is 13.00 ± 0.02 mm inhibition zone against Staphylococcus aureus.
Highlights
A good photocatalyst material must have superior properties like photoactive, able to absorb visible and UV light, biologically and chemically inert, photostable, inexpensive, and nontoxic
It can be seen in the SEM micrographs that the petals of the flowers were in the size range of 20–90 nm
The formation of flower-like TiO2 nanostructures is good for photocatalytic activity because it will help to maximize the light harvesting due to the multiple reflections of light within the interior nanoflowers [29]
Summary
A good photocatalyst material must have superior properties like photoactive, able to absorb visible and UV light, biologically and chemically inert, photostable, inexpensive, and nontoxic. Photocatalytic reaction in general involved six photocatalytic processes which are (1) charge separation process, (2) surface recombination, (3) surface trapping, (4) surface recombination, (5) interfacial charge transfer, and (6) back reaction [5] This process occurred when the absorption of light generates an electron-hole pair on the surface of TiO2, whereas the electron is promoted to the conduction band (CB) and the positive hole is made in the valence band. These holes produce hydroxyl radicals that are important in the photocatalytic reaction This reaction will continuously happen as long as the holes and electrons are present, so that it is important to have a long life of holes and electrons allowing them to migrate to the TiO2 particle surface and get trapped by the surface active sites
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