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In this paper, we demonstrated a new convenient route for in situ fabrication of well separated small sized WO(3) nanoparticles in silica spheres, through a predeposition of surfactant encapsulated polyoxotungates as tungsten source, and followed by a calcination process. In a typical procedure, selected polyoxotungates with different charges were enwrapped with dioctadecyldimethylammonium cations through electrostatic interaction. Elemental analysis, thermogravimetric analysis, and spectral characterization confirmed the formation of prepared complexes with the anticipated chemical structure. The complexes were then phase-transferred into aqueous solution that predissolved surfactant cetyltrimethylammonium bromide, and finally incorporated into silica spheres through a joint sol-gel reaction with tetraethyl orthosilicate in a well dispersed state under the protection of organic layer for polyoxotungates from the alkaline reaction condition. Transmission electron microscopic images illustrated the well dispersed WO(3) nanoparticles in the size range of ca. 2.2 nm in the silica spheres after the calcination at 465 °C. The sizes of both the silica spheres and WO(3) nanoparticles could be adjusted independently through changing the doping content to a large extent. Meanwhile, the doped polyoxotungate complexes acted as the template for the mesoporous structure in silica spheres after the calcination. Along with the increase of doping content and surfactant, the mesopore size changed little (2.0-2.9 nm), but the specific surface areas increased quite a lot. Importantly, the WO(3)-nanoparticle-doped silica spheres displayed an interesting photovoltaic property, which is favorable for the funtionalization of these nanomaterials.

Ni-doped CdS nanowires were synthesized by a simple one-step method. X-ray diffraction, X-ray photoelectron spectroscopy, and photoluminescence spectroscopy confirmed that light Ni doping can form shallow surface states due to the presence of substitutional Ni ions, and heavy Ni doping can form deep surface states due to the presence of interstitial Ni ions. Surface photovoltage spectroscopy and transient photovoltage measurements revealed that the shallow surface states can prolong the lifetime of the photogenerated charge carriers, whereas the deep surface states lead to recombination of the photogenerated charge carriers. The relationship between different surface states and the photocatalytic performance of CdS nanocrystals are discussed. The enhanced density of shallow surface states due to light Ni doping significantly promotes photocatalytic H2 production. [ABSTRACT FROM AUTHOR]

The TiO2-B nanobelt (NB)/TiO2nanoparticle (NP) sandwich-type structure photoelectrode, with controllable nanobelt length, has been used to fabricate high-efficiency dye-sensitized solar cells (DSSCs), which combine the advantages of the rapid electron transport in TiO2-B NBs and the high surface area of TiO2NPs. The results indicate that the sandwich-type photoelectrode achieves higher photoelectrical conversion efficiency when compared with the TiO2nanoparticulate electrode. Increasing the length of TiO2-B NBs has been demonstrated to improve the photoelectric conversion efficiency (η). DSSCs with the longest (10 μm) TiO2-B NBs yield the highest ηof 7.94%. The interfacial electron transport of DSSCs with different lengths of TiO2-B NBs has been quantitatively investigated using the photovoltage transient and the electrochemical impedance spectra, which demonstrates that the DSSCs with longest TiO2-B NBs display the highest electron collection efficiency and the fastest interfacial electron transfer. [ABSTRACT FROM AUTHOR]

Abstract: An original photoelectric gas sensor, fabricated by Ru(dcbpy)2(NCS)2 (dcbpy=2,2′-bipyridyl-4,4′-dicarboxylate)(RuN3)-sensitized ZnO on a comb-like electrode by surface photocurrent technique with excitation of visible light (545nm), is presented for CO and O2 detection at room temperature. The surface photocurrent (I SPC) of a sample can be dramatically enhanced and diminished depending on the properties of the gases. As a reductive gas, CO can make I SPC increase and the sensor response is linear to the change in CO concentration with a detection limit of 0.62Torr. However, I SPC decreases upon O2 adsorption, since it can capture electrons from the surface. There is no linear dependency between I SPC and concentration of O2. In this article a microscopic mechanism of the photoelectric gas sensor has also been discussed in detail. This research should be valuable for the practical application of the ZnO gas sensor. [Copyright &y& Elsevier]

Composite films of ZnS nanoparticle‐polyelectrolyte were fabricated by the layer‐by‐layer self‐assembly technique. The optical properties and structure of the films were characterized by UV‐vis absorption spectra and AFM. The films sensitized by tetrasulfonated copper phthalocyanine (CuTsPc) show wide photovoltaic response range. The surface photovoltages corresponding to the ZnS nanoparticle interband transition and CuTsPc Q band transition in the sensitized film are approximately three to four times stronger than those in the ZnS nanoparticle‐polyelectrolyte film and CuTsPc film, respectively, which is attributed to the electron transition from the excited state of CuTsPc to the conduction band of ZnS nanoparticles. [ABSTRACT FROM AUTHOR]

In this paper, ZnO nanoparticles were prepared by a sol–gel method and sensitized by azo pigment (4,4′-2-{N-[β-hydroxyl-γ-(ρ-nitroanilino)naphthyl]}azodiphenyl). Measurements of surface photocurrent by comb-like electrode and He–Ne laser and gas adsorption were performed on the ZnO/azo system. The process of photoinduced charge transport from excited dyes to nanocyrstalline ZnO was studied by surface photocurrent response (SPR). We have also discussed different effects of water and oxygen as gas adsorbates on SPR. Such a research should be valuable for the practical application of ZnO nanoparticles to semiconductor gas sensors. [Copyright &y& Elsevier]

Abstract: Monodisperse Ag/Anatase TiO2 core–shell nanoparticles were synthesized by a simple solvothermal method. Transmission electron microscopy (TEM) and X-ray diffraction (XRD) measurements confirm that the as-synthesized nanoparticles have the core–shell structure and TiO2 shell is anatase phase. Interestingly, the photocatalytic ability of the as-synthesized nanoparticles for degrading alizarin red (AR) is greatly increased compared with that of Dessuga P25. [Copyright &y& Elsevier]

The self-assembled films of CdS nanoparticle-polyelectrolyte sensitized by tetrasulfonated copper phthalocyanine (CuTsPc) were fabricated on an indium-tin-oxide (ITO) electrode by electrostatic attraction. The structure and optical properties were characterized. The films sensitized by dye show stronger photovoltaic signals than those not sensitized, which is attributed to the electron transfer from the excited state of CuTsPc to the conduction band of CdS nanoparticles. [ABSTRACT FROM AUTHOR]

Abstract: TiO2(B) was prepared by a facile green solvothermal method and further characterized by the powder X-ray diffraction (XRD), high-resolution transmission electron microscopy (HRTEM), raman spectroscopy and nitrogen sorption analysis, and it has been found that the as-synthesized sample possesses a unique crystallites/nanopores structure and has a very large surface area (484m2 g−1). Surprisingly, it exhibits the very high photocatalytic activity and good stability for the decomposition of methyl orange (MO) compared to that of P25. [ABSTRACT FROM AUTHOR]

Abstract: The ZnO nanorods with different diameters (∼300, 100, 40nm) and nanoparticles (∼6nm) were prepared, and their sensitivities to formaldehyde at room temperature were measured with and without the UV light irradiation (the intensity of light is 0.155mW/cm2). The XRD, TEM and SEM were utilized to examine the size of crystal and the morphology of material. The transient photovoltage and photoluminescence spectra were utilized to investigate the photoelectric properties of ZnO. The ZnO nanorods with diameter of ∼40nm own the highest response to formaldehyde with the UV light illumination than that of other samples. It is attributed to the large surface-to-volume ratio and high photo-generated charge efficiency, which are two key parameters to determine the gas response. The transient photovoltage results further demonstrate that the photo-generated charge efficiency of gas sensing element decreases as the surface-to-volume ratio increases (i.e. the size of crystal decreases). Therefore, the particles with highest sensitivity are of a certain size, neither the largest nor the smallest tested. Our work may supply a direction to fabricate the high performance gas sensor with UV light illumination. [Copyright &y& Elsevier]

Organic amines are a kind of industrially important starting material for the manufacture of dyes and pharmaceuticals. But monitoring low-concentration amine vapors, especially those with a high molecular weight, is still a challenging task during industrial processes because the low permeability and diffusivity of amines largely limit their interaction with the surface of sensing element. Herein, we report the template-free solvothermal synthesis of uniform nanoparticle-assembled SnO 2 microspheres with an rich interparticle porosity, and the thermal-driven tuning of their porosity structure with the sphere-like morphological preservation. This further allows us to fabricate a sensing film with a tunable interparticle porosity structure and an optimized gas diffusivity in the sensing film. As a result, the optimized SnO 2 sensing film is shown to have the ability to effectively detect low-concentration amine vapors with short response time and high response value in the testing range from 1 to 200 ppm. [ABSTRACT FROM AUTHOR]

Highlights: [•] We report a simple one-step hydrothermal synthesis on Ag2S nanoparticles. [•] The photoelectric properties of the Ag2S nanoparticles were studied. [•] A mechanism for the nucleation and growth of Ag2S NPs was proposed. [•] The concentration of surfactants impacts the grain diameter and the photoelectric properties. [Copyright &y& Elsevier]

Abstract: The surface structure of the iron oxide nanoparticles obtained by the co-precipitation method has been investigated, and a thin layer of α-FeOOH absorbed on surface of the nanoparticle is confirmed by analyses of Fourier transform infrared (FTIR), X-ray photoelectron spectra (XPS) and surface photovoltage spectroscopy (SPS). After annealed at 400°C, the α-FeOOH can be converted to γ-Fe2O3. The simple-annealed procedure resulted in the formation of Fe3O4@γ-Fe2O3 core/shell structure with improved stability and a higher magnetic saturation value, and also the simple method can be used to obtain core/shell structure in other similar system. [Copyright &y& Elsevier]