Metal oxide nanofibrous materials for photodegradation of environmental toxins
AssigneeThe Research Foundation for The State University of New York
InventorsWayne E. Jones, Jian Liu, William E. Bernier, Julia B. Tollin, Danielle McCarthy, Emilly Obuya, Jared DeCoste
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Abstract
Mixed-phase TiO2 nanofibers prepared via a sol-gel technique followed by electrospinning and calcination are provided as photocatalysts. The calcination temperature is adjusted to control the rutile phase fraction in TiO2 nanofibers relative to the anatase phase. Post-calcined TiO2 nanofibers composed of 38 wt % rutile and 62 wt % anatase exhibited the highest initial rate constant of UV photocatalysis. This can be attributed to the combined influences of the fibers' specific surface areas and their phase compositions.
Claims20
A method of forming photocatalytic titanium oxide fibers, comprising:
- forming a polymeric suspension of titanium oxide sol-gel precursor;
- electrospinning the polymeric suspension to form a titanium oxide fibrous layer;
- and
- calcining the titanium oxide fibrous layer, to produce the photocatalytic titanium oxide fibers comprising a distinct rutile phase and anatase phase comprising a ratio of rutile phase to anatase phase of at least 3:97,
- wherein the photocatalytic titanium oxide fibers are photoexcitable to produce electron-hole pairs with an ability to form reactive radical species of proximate molecules from both the conduction band and the valence band,
- the rutile phase being adapted to absorb photons, form hydroxyl radicals and hydrogen anions from surface absorbed water, and to transfer electrons to the anatase phase, and
- the anatase phase being adapted to absorb photons, receive electrons from the rutile phase, and form superoxide radicals from surface absorbed oxygen.
A method of forming photocatalytic fibers, comprising:
- suspending a polymeric titanium oxide sol-gel precursor in a solution;
- electrospinning the solution to form a titanium oxide fibrous layer comprising photocatalytic titanium oxide fibers;
- and
- calcining the titanium oxide fibrous layer to form distinct regions within the photocatalytic titanium oxide fibers having at least two distinct phases, comprising a rutile phase and an anatase phase each having a different respective bandgap, the photocatalytic titanium oxide fibers comprising a dopant which induces semiconductivity,
- wherein the photocatalytic titanium oxide fibers in the calcined titanium oxide fibrous layer are photoexcitable to produce electron-hole pairs from both a conduction band and a valence band of the at least two distinct phases,
- wherein photoexcited electrons migrate from the conduction band of a first phase to the conduction band of a second phase, and photoexcited electrons in the valence band of the second phase migrate into the valence band of the first phase, and
- wherein the calcined titanium oxide fibrous layer is configured to selectively form free radical oxygen compounds from oxygen compounds in the environment from the conduction band of the second phase and the valence band of the first phase.
A method of forming photocatalytic titanium oxide fibers, comprising:
- providing a suspension of a titanium oxide sol-gel precursor;
- forming a titanium oxide fibrous layer comprising photocatalytic titanium oxide fibers by electrospinning the titanium oxide sol-gel precursor suspension;
- and
- calcining the titanium oxide fibrous layer to form photocatalytic titanium oxide fibers having a distinct rutile phase and an anatase phase, having a ratio of rutile phase to anatase phase of between 3:97 and 97:3,
- wherein the distinct rutile phase and an anatase phase of the photocatalytic titanium oxide fibers are each configured to be photoexcitable under excitation with visible or ultraviolet light to produce electron-hole pairs, and to form reactive radical species of proximate molecules from both a conduction band of the rutile phase and a valence band of the anatase phase of the photocatalytic titanium oxide fibers.
Dependencies are inferred from the claim text.