Eu3+ doped TiO2 nanocrystals were prepared by the hydrothermal method and characterized by XRD, ESEM, IR, UV absorption and emission spectra. XRD and ESEM micrograph revealed that the samples are in pure rutile phase....Eu3+ doped TiO2 nanocrystals were prepared by the hydrothermal method and characterized by XRD, ESEM, IR, UV absorption and emission spectra. XRD and ESEM micrograph revealed that the samples are in pure rutile phase. Emission spectra under 355 nm radiative were measured to characterize the spectroscopic properties, which showed that the samples probably contain trace Tb3+ ions. The energy transfer mechanism from rutile TiO2 to the 4f shell of Tb3+ and Eu3+ was discussed in connection with the excitation and emission properties of the samples.展开更多
In the present work, the hybrid catalyst films of TiO2/CuO containing up to 10% in mol of copper were deposited onto glass surface. Precursor solutions were obtained by citrate precursor method. Films were porous and ...In the present work, the hybrid catalyst films of TiO2/CuO containing up to 10% in mol of copper were deposited onto glass surface. Precursor solutions were obtained by citrate precursor method. Films were porous and the average particle size was 20 nm determined by FEG-SEM analysis. The photocatalytic activities of these films were studied using Rhodamine B as a target compound in a fixed bed reactor developed in our laboratory and UV lamp. It was observed that the addition of copper to TiO2 increased significantly its photocatalytic activity during the oxidation of Rhodamine B. The degradation exceeded 90% within 48 hours of irradiation compared to 38% when pure TiO2 was used. Moreover, there was a reduction in the particles band gap energy when compared to that of pure TiO2. These results indicate that the TiO2/CuO films are promising catalysts for the development of fixed bed reactors to be used to treat effluents containing azo dyes.展开更多
The study focused on the modification with platinum of dark defective titania obtained via pulsed laser ablation. Both the method of Pt introduction and the nature of the Pt precursor were varied. All samples exhibite...The study focused on the modification with platinum of dark defective titania obtained via pulsed laser ablation. Both the method of Pt introduction and the nature of the Pt precursor were varied. All samples exhibited similar phase compositions, specific surface areas, and Pt contents. High-resolution transmission electron microscopy coupled with pulsed CO adsorption revealed increased dispersity when photoreduction and the hydroxonitrate complex (Me _(4) N) _(2) [Pt _(2) (OH) _(2) (NO _(3) ) _(8) ] were used. The sample featured a high content of single-atom species and subnano-sized Pt clusters. The X-ray photoelectron spectroscopy results showed that the photoreduction method facilitated the appearance of a larger number of Pt ^(2+) states, which appeared owing to the strong metal-support interaction (SMSI) eff ect of the transfer of electron density from the electron-saturated defects on the TiO _(2) surface to Pt ^(4+) . In the hydrogen evolution reaction, samples with a significant fraction of the Pt ^(2+) ionic component, capable of generating short-lived Pt^(0) single-atom sites under irradiation due to the SMSI eff ect, exhibited the highest photocatalytic activity. The 0.5Pt(C)/TiO_(2) -Ph sample exhibited the highest hydrogen yield with a quantum efficiency of 0.53, retaining its activity even after 8 h of operation.展开更多
基金the City University of Hong Kong Research Grant (9360123)
文摘Eu3+ doped TiO2 nanocrystals were prepared by the hydrothermal method and characterized by XRD, ESEM, IR, UV absorption and emission spectra. XRD and ESEM micrograph revealed that the samples are in pure rutile phase. Emission spectra under 355 nm radiative were measured to characterize the spectroscopic properties, which showed that the samples probably contain trace Tb3+ ions. The energy transfer mechanism from rutile TiO2 to the 4f shell of Tb3+ and Eu3+ was discussed in connection with the excitation and emission properties of the samples.
基金FAPESP,FAPEMIG,CAPES and CNPq for the financial support.
文摘In the present work, the hybrid catalyst films of TiO2/CuO containing up to 10% in mol of copper were deposited onto glass surface. Precursor solutions were obtained by citrate precursor method. Films were porous and the average particle size was 20 nm determined by FEG-SEM analysis. The photocatalytic activities of these films were studied using Rhodamine B as a target compound in a fixed bed reactor developed in our laboratory and UV lamp. It was observed that the addition of copper to TiO2 increased significantly its photocatalytic activity during the oxidation of Rhodamine B. The degradation exceeded 90% within 48 hours of irradiation compared to 38% when pure TiO2 was used. Moreover, there was a reduction in the particles band gap energy when compared to that of pure TiO2. These results indicate that the TiO2/CuO films are promising catalysts for the development of fixed bed reactors to be used to treat effluents containing azo dyes.
文摘The study focused on the modification with platinum of dark defective titania obtained via pulsed laser ablation. Both the method of Pt introduction and the nature of the Pt precursor were varied. All samples exhibited similar phase compositions, specific surface areas, and Pt contents. High-resolution transmission electron microscopy coupled with pulsed CO adsorption revealed increased dispersity when photoreduction and the hydroxonitrate complex (Me _(4) N) _(2) [Pt _(2) (OH) _(2) (NO _(3) ) _(8) ] were used. The sample featured a high content of single-atom species and subnano-sized Pt clusters. The X-ray photoelectron spectroscopy results showed that the photoreduction method facilitated the appearance of a larger number of Pt ^(2+) states, which appeared owing to the strong metal-support interaction (SMSI) eff ect of the transfer of electron density from the electron-saturated defects on the TiO _(2) surface to Pt ^(4+) . In the hydrogen evolution reaction, samples with a significant fraction of the Pt ^(2+) ionic component, capable of generating short-lived Pt^(0) single-atom sites under irradiation due to the SMSI eff ect, exhibited the highest photocatalytic activity. The 0.5Pt(C)/TiO_(2) -Ph sample exhibited the highest hydrogen yield with a quantum efficiency of 0.53, retaining its activity even after 8 h of operation.
