Mesoporous TiO2 nanofibers with controlled diameter, crystal size, and anatase versus rutile crystal structures are produced by calcination at 500–700 °C of precursor nanofibers of polyvinylpyrrolidone and titanium isopropoxide, obtained from a scalable gas jet fiber spinning process. These TiO2 nanofibers are used in the photocatalytic oxidation of gas‐phase ethanol at room temperature on exposure to UV irradiation. The experimental trends are analyzed using electron–hole (e‐h) charge recombination inferred from high‐intensity photoluminescence emission spectra, specific surface area, crystallinity, and the proportions of anatase and rutile phases. The nanofibers show a photocatalytic activity that is up to an order of magnitude higher than that of commercial‐grade P25 TiO2 nanoparticles because of slower e‐h recombination phenomena in the former. The results show that ethanol undergoes complete oxidation into CO2 and H2O on the nanofibers without the accumulation of the intermediate products acetaldehyde and formic acid.

We report photocatalytic activities of a set of mesoporous, hierarchical “nanorods‐on‐nanofiber” heterostructures produced from the organization of vanadium pentoxide (V2O5) nanorods on titanium dioxide (TiO2) nanofibers fabricated using gas jet fiber (GJF) spinning process. The precursor nanofibers spun from solutions of poly(vinylpyrrolidone), titanium tetraisopropoxide, and vanadium oxytriisopropoxide are calcined at 500–600 °C in air to yield the above hierarchical nanostructures. The calcination temperature and the composition of the spinning solutions are used as factors to obtain different sizes of the nanorods, nanofibers, and the crystallites. Photocatalytic oxidation of gas‐phase ethanol on the heterostructures under visible light at room temperature is studied. The materials calcined at 500 °C show oxidation of ethanol into carbon dioxide and water with about three orders of magnitude higher rate than single‐component V2O5 nanofibers and reference material V2O5 powder. The higher photocatalytic activity is attributed to the slowdown of the electron–hole charge recombination phenomena in the heterostructures as inferred from photoluminescence study. The heterostructure V2O5–TiO2 photocatalyst can be easily regenerated without sacrificing any photocatalytic performance.

Bi-component semiconducting metal oxide nanofibers with core–shell and side-by-side morphologies in mesoporous or solid cylindrical shapes are produced by gas-jet fiber process.

Silica fibers are of technological significance in view of their applications in sensing, photocatalysis, filtration, biological scaffolds, photoluminescence, composites, etc. A combination of electrospinning and sol-gel technique has been employed to synthesize inorganic or ceramic sub-micron fibers starting from a novel oligomeric pre-ceramic precursor, Poly(methylhydrosiloxane) (PMHS). The composite fibers were calcined at temperatures in the range of 550 uC to 1400 uC to obtain slica fibers. The electrospun preceramic fibers and derived silica sub-micron fibers were characterized by FESEM, TEM, XRD, Raman spectroscopy and FTIR. Calcination transformed the smooth pre-ceramic fibers to compact silica fibers that consist of nano-sized silica particles. Calcinations at lower temperatures yielded more amorphous silica fibers, but calcination at 1400 uC yielded a polymorph of crystalline silica, a-cristobalite. Building up of an ordered Si-O network with increased temperature was verified by Infra-Red and Raman Spectroscopy.Photoluminescence (PL) study of the electrospun fibers showed their potential as blue, green and red light emitters at room temperature at different excitation wavelengths, and a blue/violet emission with the UV excitation not seen previously. Although calcination of PMHS fibers decreased PL intensity, a close correspondence in both the emission and excitation PL spectra along with the PL life times of differently calcined fibers is probably owing to the presence of similar defect centers. Tuning of PL should allow potential applications in optoelectronics, medical nanoprobes and bio-labeling and sensing.