Titanium dioxide nanoparticles were synthesized by using sol gel method and their physico-chemical properties were characterized by transmission electron microscopy (TEM), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR) and UV-Vis spectrophotometer. The photocatalytic property of TiO2 nanoparticles was investigated by inactivation of Escherichia coli under irradiation of fluorescent lamp. The results showed that the size of TiO2 was in the range of 3 to 7 nm with high crystallinity of anatase phase. The sharp peaks in FTIR spectrum determined the purity of TiO2 nanoparticles and absorbance peak of UV-Vis spectrum showed the energy band gap of 3.2 eV. Optimum inactivation of E. coli was obtained at 1.0 g/L TiO2 nanoparticles, with 80% of E. coli population was inactivated. The light scattering effect and insufficient concentration are the factors that cause the less effective inactivation reaction for 2.5 g/L and 0.1 g/L TiO2 concentration.
Praseodymium ion, Pr3+ doped Gd2
O2
S nanophosphors were successfully synthesized via gamma irradiation route
along with the heat treatment. The effect of the gamma irradiation (0-150 kGy) on the structural, morphology and
photoluminescence properties of Gd2
O2
S:Pr3+ were characterized via X-ray diffraction (XRD), field emission scanning
electron microscope (FESEM) and photoluminescence spectroscopy (PL). The thermal properties of precursor sample
were tested by the thermogravimetric analysis (TGA) and differential thermal analysis (DTA). The chemical bonding of
the precursor samples were analyzed by Fourier transform infrared spectroscopy (FT-IR). The XRD result confirmed the
formation of hexagonal phase of Gd2
O2
S:Pr3+ without the presence of any impurities. The FESEM inspection showed the
non-symmetrical shape of particles transformed into grain-like shape. The optimum photoluminescence (PL) emission
intensities of Gd2-xO2
S:xPr3+ occur at 50 kGy dose of gamma irradiation and 2 mol% concentration dopant of Pr3+ ions.
The spectra under 325 nm UV excitation shows a strong green emission at 515 nm, which match the 3
P0 → 3
H4
transition
of Pr3+ ions. The Gd2
O2
S:Pr3+ nanophosphors possessed many useful approaches in various applications mainly as
radiation detection and biomedical diagnostic.
Struktur-nano TiO2 dengan pelbagai saiz dan bentuk telah disintesis melalui kaedah hidrotermal menggunakan serbuk nanozarah TiO2 sebagai prekursor. Sistem hidrotermal yang mudah, murah dan bebas templet pada suhu rawatan 180ºC, pengaruh medium alkali dengan penambahan NaOH dan KOH ke atas saiz, morfologi dan sifat fotovoltaik struktur-nano TiO2 telah dikaji. Sampel telah diperincikan oleh mikroskopi elektron transmisi (TEM), analisis penyebaran tenaga sinar-x (EDAX) manakala keupayaan fotovoltaik sel suria sensitif pewarna (DSSC) diukur menggunakan Gamry Potentiostat Series G-300. Hasil kajian dengan menggunakan agen alkali yang berlainan (NaOH dan KOH) jelas mempengaruhi morfologi TiO2 dan sel suria sensitif pewarna yang terdiri daripada struktur nanorod TiO2 menunjukkan keupayaan terbaik dengan voltan litar terbuka (Voc) sebanyak 416.8 mV, ketumpatan arus litar terbuka (Jsc) sebanyak 0.169 mA/cm2 dan kecekapan penukaran (η) sebanyak 0.0232% di bawah iluminasi lampu xenon AM 1.5.