Haimei Fan

Synthesis and Studies of the Visible‐Light Photocatalytic Properties of Near‐Monodisperse Bi‐Doped TiO2 Nanospheres

Near-monodisperse Bi-doped anatase TiO(2) nanospheres with almost uniform diameters in the range of 117 to 87 nm were prepared simply by introducing different amounts of bismuth nitrate pentahydrate into the reaction system and subsequent calcinations. X-ray diffraction, UV-visible diffuse reflectance spectra, and X-ray photoelectron spectroscopy confirm that the doped ions substitute some of the lattice titanium atoms, and furthermore, Bi(3+) and Bi(4+) ions coexist. All the Bi-doped TiO(2) samples show much better photocatalytic activity than pure TiO(2) in the degradation of rhodamine B (RhB) under the irradiation of visible light (lambda>420 nm), and, interestingly, it was found that the degradation mechanism is different from the conventional one, which has already been reported elsewhere. The detailed mechanism is discussed in this article.

Synthesis of highly efficient C-doped TiO(2) photocatalyst and its photo-generated charge-transfer properties.

Carbon-doped anatase TiO(2) was prepared by a facile hydrothermal process without adding additional carbon source. The as-prepared sample shows highly efficient photocatalytic activity, which only requires 4min and is about 11 times higher than that of Degussa P25 TiO(2) in degradation of methyl orange (MO) dye under UV light irradiation. Moreover, a highly visible-light activity is also observed. UV-vis diffuse reflectance spectra and X-ray photoelectron spectroscopy confirm that the carbon atoms are incorporated into the interstitial positions of TiO(2) lattice and form a strong interaction with titanium atoms and extend photoresponding range to 700nm. Surface photovoltage spectra (SPS) and transient photovoltage (TPV) suggest that the presence of interstitial carbons induce several localized occupied states in the gap, enhance the separation extent and restrain the recombination of the photo-induced electron and hole carriers in TiO(2).

Photoinduced charge transfer process in p-Cu2O/n-Cu2O homojunction film and its photoelectric gas-sensing properties

In this study, the p-Cu2O/n-Cu2O homojunction film was prepared by a simple two-step electrodeposition method. The photoinduced charge transfer process in p-Cu2O/n-Cu2O homojunction film was studied using surface photovoltage technique. Then, the p-Cu2O/n-Cu2O homojunction film was assembled into a photoelectric gas sensor for sensing acetaldehyde both under 405 nm and 532 nm light irradiation at room temperature. For 532 nm light irradiation, excess photoinduced electrons migrate to the irradiated n-Cu2O side affected by the interfacial built-in electric field and promote desorption of acetaldehyde, which results in a higher sensitivity than that under 405 nm light. Our results demonstrated that constructing junction structure in photoelectric gas-sensing materials is an effective approach to achieve high sensitivity at room temperature.