In the present work, we prepared two kinds of quantum sized ZnO particles whose size were 3 nm(P1) and 5 nm(P2), respectively, and studied their surface properties with surface photovoltage spectroscopy(SPS) and elect...In the present work, we prepared two kinds of quantum sized ZnO particles whose size were 3 nm(P1) and 5 nm(P2), respectively, and studied their surface properties with surface photovoltage spectroscopy(SPS) and electric field induced surface photovoltage spectroscopy(EFISPS). The photovoltaic response of the two samples showed opposite dependence on external electric field. And when electric field was applied, the thresholds of photovoltaic response of the two samples were all red shifted. The results showed that the surface properties of P1 were different from those of P2, because of their different preparation process. We assigned that basic zinc acetate structure exist on the surface of P1 sample. While for P2 sample prepared by aging P1, that kind of surface structure disappeared, but the particles might be doped with lithium ions in the aging process.展开更多
We prepared TiO 2(anatase) and Sn doped TiO 2 nanoparticlate film by Plasma enhanced Chemical Vapor Deposition(PECVD) method. XRD and XPS experiments showed that Sn was doped into the lattice of TiO 2 with a ratio of ...We prepared TiO 2(anatase) and Sn doped TiO 2 nanoparticlate film by Plasma enhanced Chemical Vapor Deposition(PECVD) method. XRD and XPS experiments showed that Sn was doped into the lattice of TiO 2 with a ratio of n (Sn)∶ n (Ti)=1∶10 . Sn doping largely enhanced the photocatalytic activity of TiO 2 film for phenol degradation. The enhancement in photoactivity by doping was discussed, based on the characterization with AFM, FTIR and EFISPS. Sn doping produced localized level of Sn 4+ in the band gap of TiO 2, about 0.4 eV below the conduction band, which could capture photogenerated electrons and reduce O 2 adsorbed on the surface of TiO 2 film, thus accelerated the photocatalytic reaction.展开更多
We present our work on direct assembly of Ag nanoparticulate film onto mica substrates without coupling agent, and investigate the potential application of this kind of assembly to SERS. Colloidal Ag is assembled onto...We present our work on direct assembly of Ag nanoparticulate film onto mica substrates without coupling agent, and investigate the potential application of this kind of assembly to SERS. Colloidal Ag is assembled onto mica substrates treated with MnCl 2 solution by electrostatic interaction, which forms a two-dimensional submonolayer. As shown by AFM study, the assembled process is size-selective, e.g., Ag particles assembled onto mica are more uniform than the mother colloid. The as-prepared Ag nanoparticulate films were shown to be active for surface-enhanced Raman scattering(SERS), as evidenced by the strongly enhanced Raman scattering from the self-assembled films(SAMs) of p-mercaptoaniline(p-MA).展开更多
Gold nanoparticles, prepared by the Frens method, have been electrostatically assemblied onto mica substrates treated with different concentration of MnCl\-2 solution. The assemblies have been investigated by means of...Gold nanoparticles, prepared by the Frens method, have been electrostatically assemblied onto mica substrates treated with different concentration of MnCl\-2 solution. The assemblies have been investigated by means of atomic force microscopy(AFM). The immersing time of bare mica in Mn\+\{2+\} solution and the concentration of Mn\+\{2+\} solution both have significant effect on the assembled process of gold nanoparticulate monolayer. The coverage of gold particles shows periodical evolution on the immersing time of mica in MnCl\-2 solution. The higher is the concentration of MnCl\-2, the shorter is the time to attain maximum coverage. An ion\|exchanged and layer\|dissociated mechanism is put forth to explain the experimental results above.展开更多
We prepared Au/Ag core-shell nanoparticles by growing Ag shell onto 12 nm Au core, using silver nitrate and sodium citrate as the reactants. By changing the molar ratio of Ag to Au, the shell thickness and thus the si...We prepared Au/Ag core-shell nanoparticles by growing Ag shell onto 12 nm Au core, using silver nitrate and sodium citrate as the reactants. By changing the molar ratio of Ag to Au, the shell thickness and thus the size of bimetallic particles could be controlled in convenient way. The formation of core-shell structure was proved by UV-Vis spectra, transmission electron microscopy(TEM), etc.. The core-shell particles showed a more narrow size distribution than Ag colloid prepared without Au core. The SERS activity of the core-shell particles was investigated by using 2,4-dimethylpyridine as the probe, which strongly indicated their potential application in SERS substrate materials.展开更多
文摘In the present work, we prepared two kinds of quantum sized ZnO particles whose size were 3 nm(P1) and 5 nm(P2), respectively, and studied their surface properties with surface photovoltage spectroscopy(SPS) and electric field induced surface photovoltage spectroscopy(EFISPS). The photovoltaic response of the two samples showed opposite dependence on external electric field. And when electric field was applied, the thresholds of photovoltaic response of the two samples were all red shifted. The results showed that the surface properties of P1 were different from those of P2, because of their different preparation process. We assigned that basic zinc acetate structure exist on the surface of P1 sample. While for P2 sample prepared by aging P1, that kind of surface structure disappeared, but the particles might be doped with lithium ions in the aging process.
文摘We prepared TiO 2(anatase) and Sn doped TiO 2 nanoparticlate film by Plasma enhanced Chemical Vapor Deposition(PECVD) method. XRD and XPS experiments showed that Sn was doped into the lattice of TiO 2 with a ratio of n (Sn)∶ n (Ti)=1∶10 . Sn doping largely enhanced the photocatalytic activity of TiO 2 film for phenol degradation. The enhancement in photoactivity by doping was discussed, based on the characterization with AFM, FTIR and EFISPS. Sn doping produced localized level of Sn 4+ in the band gap of TiO 2, about 0.4 eV below the conduction band, which could capture photogenerated electrons and reduce O 2 adsorbed on the surface of TiO 2 film, thus accelerated the photocatalytic reaction.
文摘We present our work on direct assembly of Ag nanoparticulate film onto mica substrates without coupling agent, and investigate the potential application of this kind of assembly to SERS. Colloidal Ag is assembled onto mica substrates treated with MnCl 2 solution by electrostatic interaction, which forms a two-dimensional submonolayer. As shown by AFM study, the assembled process is size-selective, e.g., Ag particles assembled onto mica are more uniform than the mother colloid. The as-prepared Ag nanoparticulate films were shown to be active for surface-enhanced Raman scattering(SERS), as evidenced by the strongly enhanced Raman scattering from the self-assembled films(SAMs) of p-mercaptoaniline(p-MA).
文摘Gold nanoparticles, prepared by the Frens method, have been electrostatically assemblied onto mica substrates treated with different concentration of MnCl\-2 solution. The assemblies have been investigated by means of atomic force microscopy(AFM). The immersing time of bare mica in Mn\+\{2+\} solution and the concentration of Mn\+\{2+\} solution both have significant effect on the assembled process of gold nanoparticulate monolayer. The coverage of gold particles shows periodical evolution on the immersing time of mica in MnCl\-2 solution. The higher is the concentration of MnCl\-2, the shorter is the time to attain maximum coverage. An ion\|exchanged and layer\|dissociated mechanism is put forth to explain the experimental results above.
文摘We prepared Au/Ag core-shell nanoparticles by growing Ag shell onto 12 nm Au core, using silver nitrate and sodium citrate as the reactants. By changing the molar ratio of Ag to Au, the shell thickness and thus the size of bimetallic particles could be controlled in convenient way. The formation of core-shell structure was proved by UV-Vis spectra, transmission electron microscopy(TEM), etc.. The core-shell particles showed a more narrow size distribution than Ag colloid prepared without Au core. The SERS activity of the core-shell particles was investigated by using 2,4-dimethylpyridine as the probe, which strongly indicated their potential application in SERS substrate materials.
