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A microwave-assisted hydrothermal method has been developed as an efficient approach to readily induce phase transition of titanate assemblies in conjunction with decoration of Cu2O clusters on the surface. The influence of Cu2+ ions on the hydrothermally induced structural evolution was examined, and the roles of heterojunctions in the resulting composites in charge separation for improved photocatalytic activity were clarified. Hierarchical titanate assemblies with high adsorption capacity for Cu2+ ions (95.7 mg/g) were prepared from a low alkaline condition. Microwave-assisted hydrothermal treatment was then used to transform the adsorbents into Cu2O/titanate/titania photocatalysts in 20 min via inducing titanate-to-titania and Cu2+-to-Cu2O dual transitions. While tubular architecture was maintained in the composites, the Cu2O clusters highly dispersed on the surface. Adsorbed Cu2+ ions have been found to retard the titanate-to-titania transformation locally, thus leading to Cu2O/titanate/titania heter...

In this study, a novel sol−gel-derived Cu/TiO2 adsorbent has been demonstrated to exhibit exceptional capacities of 40.62, 49.52, and 108.48 mg PH3/g Cu/TiO2 for the oxidative capture of phosphine (PH3) in N2, air, and humidified air, respectively. We have proposed the oxidative mechanisms for PH3 on the Cu/TiO2 sample on the basis of elemental, chemical state, functional group, and microstructural analysis. Moreover, the influence of O2 and water vapor on the capture capacity is discussed. The transformation of PH3 followed the sequence of PH2 → H2P−OH → HP(OH)2 → P(OH)3 → HO−P═O → H3PO4. At the same time, the CuO/Cu(OH)2 moieties in the TiO2 lattice were reduced to Cu0. The H2P−OH and HO−P═O are the two stable intermediates, and they occupied the active species to inhibit further chemisorption. Direct oxidation of PH3 or the intermediates with adsorbed O2 was not efficient. However, the Cu/TiO2 sample catalyzed their interactions via reduction and then oxidation of the Cu2+ ions. Water vapor acts as a c...

The microstructures and band gaps of sol−gel-derived ZrO2 thin films incorporating seven-transition-metal ions (Cr3+, Mn2+, Fe3+, Co2+, Ni2+, Cu2+, and Zn2+) were investigated at 550 and 950 °C. Results obtained in this study indicate that the chemical states of the dopants play pivotal roles in controlling the physicochemical properties of the metal-doped ZrO2 thin films at different temperatures. The reduction of Cr3+ and Co2+ to zerovalent metals expanded the d spacings and enlarged the crystallite sizes in the doped ZrO2 thin films at 550 °C, while the incorporation of Mn2+, Fe3+, Ni2+, Cu2+, and Zn2+ contracted the d spacings of the ZrO2 lattices in the solid solutions. The solubility of the dopants in the ZrO2 lattices decreased at 950 °C, and this phenomenon induced an m-tetragonal-to-monoclinic phase transformation in the doped ZrO2. The phase transformation was suppressed in the Cr-, Fe-, and Cu-doped ZrO2 thin films as a result of the reduction of Cr3+ and Fe3+ to species having larger sizes tha...

The determination of distribution coefficients is important for prediction of the chemical pathways of organic compounds in the environment. Solid-phase microextraction (SPME) is a convenient and effective method to measure the distribution of chemicals in a two-phase system. In the present study, the SPME distribution coefficient (K(spme)) of 16 priority aromatic hydrocarbons (PAHs) was determined with 100-microm poly(dimethylsiloxane) (PDMS) and 85-microm polyacrylate (PA) fibers. The partition coefficients and LeBas molar volumes were used to describe the linearity of the log K(spme) values of PAHs. Also, the validation of the distribution coefficient was examined using different sample volumes. The extraction time was dependent on the types of PAHs, and 20 min to 60 h was needed to reach equilibrium. The determined log K(spme) values ranged from 3.02 to 5.69 and from 3.37 to 5.62 for 100-microm PDMS and 85-microm PA fibers, respectively. Higher K(spme) values of low-ring PAHs were observed using 85-microm PA fiber. Good linear relationships between log K(ow) and log K(spme) for PAHs from naphthalene to benzo[alpha]pyrene and from naphthalene to chrysene for 100-microm PDMS and 85-microm PA fibers, respectively, were obtained. The correlation coefficients were 0.969 and 0.967, respectively. The linear relationship between log K(spme) and the LeBas molar volume was only up to benz[alpha]anthracene for 85-microm PA fiber and up to chrysene for 100-microm PDMS fiber. Moreover, the effect of sample volume can be predicted using the partition coefficient theory and excellent agreement was obtained between the experimental and theoretical absorbed amounts of low-ring PAHs. This result shows that the determined log K(spme) is more accurate than the previous method for estimating analytes with log K(ow)6 as well as for predicting the partitioning behaviors between SPME fiber and water.