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Perovskite solar cells (PSC) are intensively studied due to their low-cost processing and high light-to-electricity conversion efficiency. However, the difficulty of the large scale fabrication hinders their practical applications, and the structure tuning of the nanomaterials to optimize PSC is still challenging. In this study, we fabricate nanosheet-based PSCs using mesoscopic TiO 2 nanosheets (NS) and p-type NiO nanosheets (NS) as electron transport material (ETM) and inorganic hole transport material (HTM), respectively. Furthermore, as the counter electrode (CE), carbon black/graphite can be applied by screen printing process to fabricate PSCs with the TiO 2 /ZrO 2 /NiO/carbon (CH 3 NH 3 PbI 3 ) structure. The nanosheet-based PSC with printable carbon counter electrode shows a promising conversion efficency of 7.50%, significantly higher than the value of 6.40% of the device using the HTM of NiO nanoparticles (NP). The electrochemical impedance analysis exhibits that NS structured PSC can decrease the electron recombination effectively and enhance the collection of the charge carriers. This research presents a novel nanostructured PSC with printable carbon counter electrode, which is promising for PSC engineering technique and large scale manufacture with low cost. [ABSTRACT FROM AUTHOR]

Photocatalytic hydrogen production from water splitting is of promising potential to resolve the energy shortage and environmental concerns. During the past decade, carbon materials have shown great ability to enhance the photocatalytic hydrogen-production performance of semiconductor photocatalysts. This review provides a comprehensive overview of carbon materials such as CNTs, graphene, C 60 , carbon quantum dots, carbon fibers, activated carbon, carbon black, etc. in enhancing the performance of semiconductor photocatalysts for H 2 production from photocatalytic water splitting. The roles of carbon materials including supporting material, increasing adsorption and active sites, electron acceptor and transport channel, cocatalyst, photosensitization, photocatalyst, band gap narrowing effect are explicated in detail. Also, strategies for improving the photocatalytic hydrogen-production efficiency of carbon-based photocatalytic materials are discussed in terms of surface chemical functionalization of the carbon materials, doping effect of the carbon materials and interface engineering between semiconductors and carbon materials. Finally, the concluding remarks and the current challenges are highlighted with some perspectives for the future development of carbon-based photocatalytic materials. [ABSTRACT FROM AUTHOR]

Photocatalytic conversion of CO 2 into hydrocarbon fuels using semiconductor photocatalysts has attracted great attention, which is considered as a promising approach to resolve the energy shortage and greenhouse effect. In this work, amine-functionalized g-C 3 N 4 was prepared by heating urea at 500 °C, with a subsequent functionalization treatment by monoethanolamine solution. The amine-functionalized g-C 3 N 4 exhibits improved photocatalytic performance on CO 2 photoreduction, which can be attributed to the enhanced CO 2 adsorption capacity. The optimized photocatalyst shows much higher CO 2 conversion efficiency as compared to pure g-C 3 N 4 under the same conditions, with a CH 4 -production rate of 0.34 μmol h −1 g −1 and CH 3 OH-production rate of 0.28 μmol h −1 g −1 . This work demonstrates the surface amine functionalization is a successful strategy to improve the CO 2 adsorption capacity of g-C 3 N 4 for the enhancement of CO 2 photoreduction activity. [ABSTRACT FROM AUTHOR]

Mesoporous AlOOH with deposited Pt (Pt/AlOOH) catalyst was prepared by combining the microemulsion-assisted synthesis of AlOOH nanoflakes with NaBH 4 -reduction of Pt precursor, and exhibited a remarkable catalytic activity as well as stability for elimination of formaldehyde (HCHO) vapor at room temperature. As compared to Pt deposited on calcined AlOOH (Pt/AlOOH-c), Pt on a commercial Al 2 O 3 (Pt/c-Al 2 O 3 ) and Pt on P25 (Pt/TiO 2 ), the Pt/AlOOH nanoflakes showed the highest catalytic activity toward decomposition of HCHO at room temperature. The excellent performance of Pt/AlOOH nanoflakes could be attributed to the abundance of surface hydroxyls, high dispersion of Pt nanoparticles, excellent adsorption performance of AlOOH, and its high specific surface area and large pore volume. The mechanism of HCHO decomposition was investigated with respect to the behavior of adsorbed intermediates on Pt/AlOOH surface at room temperature using in situ DRIFTS. The result suggests that surface formate is the main reaction intermediate during the HCHO oxidation and it could be directly oxidized to CO 2 in the presence of O 2 . By taking advantage of high adsorption affinity of AlOOH nanoflakes and excellent catalytic activity of Pt nanoparticles toward HCHO it was possible to design a superior nanostructured catalyst for room temperature decomposition of HCHO. This strategy can be also used to fabricate novel nanostructured catalysts for advanced applications such as environmental remediation. [ABSTRACT FROM AUTHOR]

Highlights: [•] CdS with various morphologies prepared by solvothermal method. [•] Solvent influencing morphology and photocatalytic H2-production activity of CdS. [•] The highest H2-production activity observed for CdS nanowires. [Copyright &y& Elsevier]

Highlight: [•] Visible-light-responsive plasmonic Ag@AgCl composite immobilized on titanate nanowire films was prepared. [•] The as-prepared films exhibit higher visible-light photocatalytic performance for the degradation of MO than P25. [•] The samples also show enhanced photocatalytic activity for the degradation of RhB and phenol. [•] Highly reactive species like Cl0 and O2 − is responsible for the photoreactivity. [Copyright &y& Elsevier]

Highlights: [•] The photocatalytic mechanism of visible-light response N S codoped anatase TiO2 was first investigated by the first-principles. [•] The O-poor growth condition is beneficial to the formation of N S codoped anatase TiO2. [•] The bent and flat impurity levels were the separation and combination centers of photogenerated electrons and holes, respectively. [•] The dominant oxidant species during photocatalytic reaction for N S codoped TiO2 was hole and OH radical instead of O2 − ion. [ABSTRACT FROM AUTHOR]

Abstract: Carbon quantum dots (CDs) with an average size of less than 10nm were prepared by ionic liquid-assisted electrochemical exfoliation of graphite electrode, and developed as photoluminescence (PL) and electrochemiluminescence (ECL) probes for efficient detecting Ru(bpy)3 2+ in the solution based on the quenching of the PL emission of CDs and enhanced ECL of Ru(bpy)3 2+, respectively. The PL and ECL probes exhibited a detection limit of 0.72 and 0.43μM, respectively. The PL and ECL properties of CDs and Ru(bpy)3 2+ will provide a new route to study the novel materials and broaden the use of them in analyte detection. [Copyright &y& Elsevier]

Abstract: Graphene, a single layer of graphite, possesses a unique two-dimensional structure, high conductivity, superior electron mobility and extremely high specific surface area, and can be obtained on a large scale at low cost. Thus, it has been regarded as an excellent catalyst support. Recently, graphene-based semiconductor photocatalysts have attracted more attention due to their enhanced photocatalytic activity. In this work, hierarchical macro/mesoporpous TiO2–graphene composites with low loadings (0–0.2wt.%) of graphene were first produced by a simple one-step hydrothermal method using tetrabutyl titanate as the titanium precursor. The prepared composite samples presented enhanced photocatalytic activity in photodegradation of acetone in air. Graphene content exhibited an obvious influence on photocatalytic activity and the optimal graphene addition content was determined. At the optimal graphene concentration (0.05wt.%), the prepared composites showed the highest photocatalytic activity, exceeding that of pure TiO2 and Degussa P-25 by a factor of 1.7 and 1.6, respectively. The enhanced photocatalytic activity is due to graphene as an excellent electron acceptor and transporter, thus reducing the recombination of charge carriers and enhancing the photocatalytic activity. The transient photocurrent response experiment further confirmed the transfer of photogenerated electrons from TiO2 to graphene and the suggested mechanism. [Copyright &y& Elsevier]

Abstract: Semiconductor photocatalysts are of great significance in solar energy conversion and environmental remediation. To overcome serious drawbacks of these materials with respect to narrow light-response range and low quantum efficiency, a variety of strategies have been developed in the past decades to enhance the light harvesting and excitation as well as the charge transfer against recombination. In particular, fluorination of semiconductor photocatalysts can be employed to modify their surface and bulk properties, and consequently, to enhance their photocatalytic performance. This review presents a comprehensive description of the F-mediated synthesis and unique properties of fluorinated semiconductor photocatalysts, in particular titanium dioxide (TiO2). The available strategies for the synthesis of fluorinated photocatalysts include post-synthesis fluorination and in-situ fluorination. Depending on the synthesis route and conditions, it is possible to control the chemical nature of incorporated fluorine (such as adsorbed fluoride and lattice-doped fluorine) and the fluoride-mediated crystal modification and organization, which often results in exceptional surface and bulk physicochemical properties, giving rise to unique photocatalytic properties. Significantly, the surface fluorination induces unusual adsorption behavior and interfacial charge transfer dynamics, directly affecting photocatalytic redox properties of the surface-fluorinated photocatalysts. The lattice fluorine-doping, sole or cooperative with other complementary co-dopants, introduces special localized electronic structures and surface defect states, accounting for the exceptional visible-light photoactivity of the fluorine-doped photocatalysts. Finally, recent advances in the synthesis and properties of fluorinated photocatalysts are summarized along with perspectives on further developments in this area of research. [Copyright &y& Elsevier]

Abstract: Novel electrocatalysts Au/TiO2 nanotube arrays (Au/TiO2NTs) were prepared by loading low-content(1.9at.%) of Au nanoparticles (AuNPs) onto highly ordered TiO2 nanotube arrays (TiO2NTs). Ethanol electrooxidation indicates that visible-light (λ>400nm) irradiation can significantly enhance the activity as well as resistpoisoning of Au/TiO2NTs electrocatalysts that are activated by plasmon resonance. Au/TiO2NTs catalysts calcinated at 300°C display the highest performance due to the strong synergistic interactions between TiO2 and Au NPs. The combination of visible-light irradiation with a controllable potential offers a new strategyfor enhancing the performance of anodes in direct ethanol fuel cell (DEFC). [Copyright &y& Elsevier]

Abstract: Dye-sensitized solar cells (DSSCs) based on anatase TiO2 hollow spheres (TiO2HS)/multi-walled carbon nanotubes (CNT) nanocomposite films are prepared by a directly mechanical mixing and doctor blade method. The prepared samples are characterized by scanning electron microscopy, transmission electron microscopy, X-ray diffraction, UV–vis absorption spectroscopy and N2 adsorption–desorption isotherms. The photoelectric conversion performances of the DSSCs based on TiO2HS/CNT composite film electrodes are also compared with commercial-grade Degussa P25 TiO2 nanoparticles (P25)/CNT composite solar cells at the same film thickness. The results indicate that the photoelectric conversion efficiencies (η) of the TiO2HS/CNT composite DSSCs are dependent on CNT loading in the electrodes. A small amount of CNT clearly enhances DSSC efficiency, while excessive CNT loading significantly lowers their performance. The former is because CNT enhance the transport of electrons from the films to FTO substrates. The latter is due to high CNT loading shielding the visible light from being adsorbed by dyes. [Copyright &y& Elsevier]

Abstract: Dye-sensitized solar cells (DSSCs) are fabricated based on double-layered composite films of TiO2 nanoparticles and hollow spheres. The photoelectric conversion performances of DSSCs based on nanoparticles/nanoparticles (PP), hollow spheres/hollow spheres (HH), hollow spheres/nanoparticles (HP), and nanoparticles/hollow spheres (PH) double-layered films are investigated, and their photo-electric conversion efficiencies are 4.33, 4.72, 4.93 and 5.28%, respectively. The enhanced performance of TiO2 nanoparticles/hollow spheres double-layered composite film solar cells can be attributed to the combined effect of following factors. The light scattering of overlayer hollow spheres enhances harvesting light of the DSSCs and the underlayer TiO2 nanoparticle layer ensures good electronic contact between film electrode and the F-doped tin oxide (FTO) glass substrate. Furthermore, the high surface areas and pore volume of TiO2 hollow spheres are respectively beneficial to adsorption of dye molecules and transfer of electrolyte solution. [Copyright &y& Elsevier]

Abstract: Preparation of anatase TiO2 with high themal stability is of great importance for its environmental application. In this work, TiOF2 was first synthesized by a simple microwave-assisted hydrothermal route using tetrabutyl titanate and hydrofluoric acid as precursors at 200°C for 20min. Then the resulted precipitates were calcined at different temperatures (300–1000°C) for 2h. The as-prepared samples were characterized by X-ray diffraction, Raman spectrum, scanning electron microscopy, N2 adsorption–desorption isotherms and X-ray photoelectron spectroscopy. The photocatalytic activity was evaluated using Brilliant Red X3B, an anionic azo dye, as the target organic molecule under UV light irradiation. The results showed that the prepared TiOF2 exhibited weak or no photocatalytic activity. The phase transformation of TiOF2 to anatase TiO2 occurred at about 300°C. The prepared anatase TiO2 from TiOF2 showed very high thermal stability and the anatase-to-rutile phase transformation temperature was up to 1000°C. Fluoride ions played an important role in the improvement of thermal stability of anatase TiO2 by strongly adsorbing on the crystal planes of anatase to stabilize the anatase structure. The 700°C-calcined sample showed the highest photocatalytic activity due to its relative good crystallization and high specific surface areas. [Copyright &y& Elsevier]

Abstract: Trifluoroacetic acid (TFA) modified TiO2 (TFA-TiO2) hollow microspheres were prepared by one-pot hydrothermal treatment of Ti(SO4)2 in the presence of TFA at 180°C for 12h. The prepared samples were characterized by X-ray diffraction, scanning and transmission electron microscopy, X-ray photoelectron spectroscopy, N2 adsorption–desorption isotherms and Fourier transform infrared. The production rates of surface of UV-illuminated TiO2 were detected by a photoluminescence (PL) method using terephthalic acid (TA) as probe molecule. The photocatalytic activity was evaluated by the photocatalytic decomposition of acetone in air under UV light illumination. The results show that TFA not only induces the formation of hollow microspheres, but also enhances their crystallization. The molar ratios of TFA to Ti(SO4)2 (R) have a great influence on photocatalytic activity. When R is in the range of 0.5–5, the photocatalytic activity of the samples is higher than that of commercial Degussa P25 TiO2 powders (P25) and pure TiO2 samples. At R =2, the photocatalytic activity of the sample reaches the highest and exceeds that of P25 by a factor of more than two times. This is ascribed to the fact that the former has hollow interior and bimodal mesoporous shells enhancing harvesting of light and the transfer and transport of reactant and product molecules, also, the surface-adsorbed TFA can reduce the recombination of photo-generated electrons and holes. [Copyright &y& Elsevier]

Abstract: Bimodal nanocrystalline mesoporous TiO2 powders with highly photocatalytic activity were prepared by a hydrothermal method using tetrabutylorthotitanate as precursor, and then dried in microwave oven. The prepared samples were characterized by XRD, SEM, TEM, HRTEM and N2 adsorption–desorption measurement. The photocatalytic activity was evaluated by the photocatalytic degradation of acetone in air under UV light irradiation at room temperature. The effects of microwave drying on the microstructures and photocatalytic activity of the TiO2 powders were investigated and discussed. The results show that microwave drying not only promotes the growth of the pores but also greatly reduces the state of agglomeration within the powders. All the microwave-dried TiO2 powders show higher photocatalytic activity than Degussa P-25 (P25) and the TiO2 powders dried by conventional method. [Copyright &y& Elsevier]

Abstract: Highly ordered TiO2 nanotube arrays (TNs) are prepared by electrochemical anodization of titanium foil in a mixed electrolyte solution of glycerol and NH4F and then calcined at various temperatures. The prepared samples are characterized by X-ray diffraction, scanning electron microscopy and transmission electron microscopy. The photocatalytic activity is evaluated by photocatalytic degradation of methyl orange (MO) aqueous solution under UV light irradiation. The production of hydroxyl radicals (e surface of UV-irradiated samples is detected by a photoluminescence (PL) technique using terephthalic acid (TA) as a probe molecule. The transient photocurrent response is measured by several on–off cycles of intermittent irradiation. The results show that low temperatures (below 600°C) have no great influence on surface morphology and architecture of the TNs sample and the prepared TNs can be stable up to ca. 600°C. At 800°C, the nanotube arrays are completely destroyed and only dense rutile crystallites are observed. The photocatalytic activity, formation rate of hydroxyl radicals and photocurrent of the TNs increases with increasing temperatures (from 300 to 600°C) due to the enhancement of crystallization. Especially, at 600°C, the sample shows the highest photocatalytic activity due to its bi-phase composition, good crystallization and remaining tubular structures. With further increase in the calcination temperature from 600 to 800°C, the photocatalytic activity rapidly decreases due to the vanishing of anatase phase, collapse of nanotube structures and decrease of surface areas. [Copyright &y& Elsevier]

Abstract: To study the synergistic effects of hollow structure and surface fluorination on the photoactivity of TiO2, TiO2 hollow microspheres were synthesized by a hydrolysis–precipitate method using sulfonated polystyrene (PS) as templates and tetrabutylorthotitanate (TBOT) as precursor, and then calcined at 500°C for 2h. The calcined samples were characterized by X-ray diffraction, scanning electron microscopy, transmission electron microscopy and N2 sorption. Photocatalytic activity was evaluated using reactive brilliant red X3B, an anionic organic dye, as a model pollutant in water. The results show that the photocatalytic activity of TiO2 hollow microspheres is significantly higher than that of TiO2 nanoparticles prepared in the same experimental conditions. At pH 7 and 3, the apparent rate constants of the former exceed that of the latter by a factor of 3.38 and 3.15, respectively. After surface fluorination at pH 3, the photoactivity of hollow microspheres and nanoparticles further increases for another 1.61 and 2.19 times, respectively. The synergistic effect of surface fluorination and hollow structure can also be used to prepare other highly efficient photocatalyst. [Copyright &y& Elsevier]

Abstract: Dye-sensitized solar cells (DSSCs) are fabricated based on hollow anatase TiO2 (HA-TiO2) spheres synthesized by a chemically induced self-transformation (CIST) strategy using urea as a base catalyst, whose walls are composed of anatase nanocrystals and exhibit hierarchical porosity. TiO2 hollow structured materials not only have low density, high specific surface areas, and hierarchically porous structures, but also exhibit high light-collection efficiency and fast motion of charge carriers. Effects of calcination temperatures on the performance of HA-TiO2 solar cells are investigated and discussed. With increasing calcination temperatures, the light–electricity conversion efficiencies (η) increase. At 600°C, HA-TiO2 cells reach the highest efficiency. The performances of HA-TiO2 cells are also compared with Degussa P-25 (P25) TiO2 nanoparticle cells at the same film thickness, and their optimal efficiencies at 600°C are 4.82 and 4.35%, respectively. The enhanced performance of HA-TiO2 cells is due to their high surface area and hierarchically nanoporous structures when compared with the nonporous TiO2 nanoparticles (P25). [Copyright &y& Elsevier]

Abstract: Bimodal mesoporous TiO2 microspheres with high photocatalytic activity were prepared by a hydrothermal method using titanium sulfate as precursor in the presence of urea. The results indicate that all prepared samples show bimodal pore-size distributions in the mesoporous region: smaller intra-aggregated pores with peak pore diameter of ca. 2nm and larger inter-aggregated pores with peak pore diameter of ca. 12.5nm. The molar ratio of urea to Ti(SO4)2 (R u) has an obvious influence on the morphology, microstructure and photocatalytic activity of TiO2. With increasing R u, specific surface areas and porosity increase, contrarily, the crystallite size and relative anatase crystallinity decrease. The photocatalytic activity first increases with R u. At R u =2.0, the photocatalytic activity reaches the highest and is obviously higher than that of Degussa P25. With further increasing R u, the photocatalytic activity decreases. The formation rate of hydroxyl radicals during photocatalysis has a positive correlation with the photocatalytic activity. [Copyright &y& Elsevier]

Abstract: Dye-sensitized solar cells (DSSCs) are fabricated based on ordered titanate nanotube (TNT) films obtained by electrophoretic deposition (EPD) method. Calcination temperatures show a great influence on the performance of TNT solar cells. At 300°C, the cells exhibit very low photo-electric conversion efficiency. At 400°C, the efficiency obviously increases. At 600°C, the cells show the highest efficiency, which is higher than the efficiency of the cells made from commercial-grade Degussa P25 TiO2 nanoparticles (P25). [Copyright &y& Elsevier]

Abstract: Hierarchically flower-like tungsten trioxide assemblies were fabricated on a large scale by a simple hydrothermal treatment of sodium tungstate in aqueous solution of nitric acid. The as-prepared samples were characterized by X-ray diffraction, scanning electron microscopy and N2 adsorption–desorption measurements. The photocatalytic activity was evaluated by photocatalytic decolorization of rhodamine B aqueous solution under visible-light irradiation. It was found that the three-dimensional tungsten trioxide assemblies were constructed from two-dimensional layers, which were further composed of a large number of interconnected lathy nanoplates with different sizes. Such flower-like assemblies exhibited hierarchically porous structure and higher visible-light photocatalytic activity than the samples without such hierarchical structures due to their specific hierarchical pores that served as the transport paths for light and reactants. After five recycles for the photodegradation of RhB, the catalyst did not exhibit any great loss in activity, confirming hierarchically flower-like tungsten trioxide was stability and not photocorroded. This study may provide new insight into environmentally benign preparation and design of novel photocatalytic materials and enhancement of photocatalytic activity. [Copyright &y& Elsevier]

Abstract: Fe-doped TiO2 (Fe-TiO2) nanorods were prepared by an impregnating-calcination method using the hydrothermally prepared titanate nanotubes as precursors and Fe(NO3)3 as dopant. The as-prepared samples were characterized by scanning electron microscope, transmission electron microscope, X-ray diffraction, X-ray photoelectron spectroscopy, N2 adsorption–desorption isotherms and UV–vis spectroscopy. The photocatalytic activity was evaluated by the photocatalytic oxidation of acetone in air under visible-light irradiation. The results show that Fe-doping greatly enhance the visible-light photocatalytic activity of mesoporous TiO2 nanorods, and when the atomic ratio of Fe/Ti (R Fe) is in the range of 0.1–1.0%, the photocatalytic activity of the samples is higher than that of Degussa P25 and pure TiO2 nanorods. At R Fe =0.5%, the photocatalytic activity of Fe-TiO2 nanorods exceeds that of Degussa P25 by a factor of more than two times. This is ascribed to the fact that the one-dimensional nanostructure can enhance the transfer and transport of charge carrier, the Fe-doping induces the shift of the absorption edge into the visible-light range with the narrowing of the band gap and reduces the recombination of photo-generated electrons and holes. Furthermore, the first-principle density functional theory (DFT) calculation further confirms the red shift of absorption edges and the narrowing of band gap of Fe-TiO2 nanorods. [Copyright &y& Elsevier]

Abstract: Mesoporous titania nanospheres with high specific surface area and good photocatalytic activity were fabricated on a large scale by a simple spray-hydrolytic method at 90°C. The as-prepared TiO2 spherical powders were characterized by X-ray diffraction, N2 adsorption–desorption measurements, field emission scanning electron microscope, transmission electron microscopy, UV–visible diffuse reflectance spectra and photocurrent measurements. The photocatalytic activity was evaluated by photocatalytic decomposition of toluene in air. The effects of calcination temperatures on the microstructures and photocatalytic activity of the TiO2 powders were investigated and discussed. The results revealed that a large amount of mesoporous titania nanospheres could spontaneously form by self-assembly of countless tiny TiO2 primary nanoparticle during the spray hydrolysis at 90°C. The calcination temperature exhibited a strong effect on the microstructures and photocatalytic activity of the prepared titania. The 400°C-calcined sample showed the highest photocatalytic activity and was about two times higher than that of Degussa P25. At 600°C, the photocatalytic activity decreased because of the destruction of bimodal mesoporous structure of the titania and the drastic decrease of specific surface areas. [Copyright &y& Elsevier]

Abstract: Hierarchically organized γ-AlOOH hollow spheres with nanoflake-like porous surface textures were fabricated by chemically induced self-transformation of metastable solid particles of amorphous aluminium oxyhydroxide produced in situ within hydrothermal reaction mixtures containing aluminium sulfate and urea. Thermal treatment of the γ-AlOOH product at 600°C produced intact hollow spheres of γ-Al2O3. Formation of the hollow γ-AlOOH structures was strongly dependent on the reaction temperature and time, as well as the concentration and molar ratio of the reactants. Hollow γ-AlOOH spheres were not obtained using mixtures of urea and aluminium nitrate or aluminium chloride, as metastable precursor particles were not produced under these conditions. In general, the described method is efficient and environmentally benign, and has significant advantages over traditional template approaches to the large-scale production of hollow inorganic materials. The prepared hierarchically organized γ-AlOOH and γ-Al2O3 hollow spheres should have important applications in areas of catalysis, separation science, biomedical engineering and nanotechnology. [Copyright &y& Elsevier]

Abstract: Peanut-shaped CaCO3 aggregates, featured of two dandelion-like heads built up from rod-like subunits, have been synthesized via a facile precipitation reaction between Na2CO3 and CaCl2 at ambient temperature in the presence of magnesium ions and ethanol solvent. The as-prepared products were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM) and inductively coupled plasma atomic emission spectrometry (ICP-AES). The results show that a high magnesium concentration and ethanol solvent are necessary for the formation of the unusual peanut-like aggregates. In addition, a multistep phase transformation process from amorphous calcium carbonate (ACC) to a mixture of ACC and calcite and ultimately to calcite and aragonite was observed in the formation process of the unusual structures. A possible mechanism for the formation of the unusual peanut-shape aggregates has been proposed and discussed. [Copyright &y& Elsevier]

Abstract: Tungsten trioxide hollow microspheres were prepared by immersing SrWO4 microspheres in a concentrated HNO3 solution, and then calcined at different temperatures. The prepared tungsten oxide samples were characterized by X–ray diffraction, X–ray photoelectron spectroscopy, Fourier transform infrared spectra, differential thermal analysis–thermogravimetry, UV–visible spectrophotometry, scanning electron microscopy, N2 adsorption/desorption measurements. The photocatalytic activity of the samples was evaluated by photocatalytic decolorization of rhodamine B aqueous solution under visible-light irradiation. It was found that with increasing calcination temperatures, the average crystallite size and average pore size increased, on the contrary, Brunauer–Emmett–Teller-specific surface areas decreased. However, pore volume and porosity increased firstly, and then decreased. Increasing calcination temperatures resulted in the changes of surface morphology of hollow microspheres. The un-calcined and 300°C-calcined samples showed higher photocatalytic activity than other samples. At 400°C, the photocatalytic activity decreased greatly due to the decrease of specific surface areas. At 500°C, the photocatalytic activity of the samples increased again due to the junction effect of two phases. [Copyright &y& Elsevier]

Abstract: The morphogenesis and phase changes of calcium carbonate in an ethanol/water mixed solvent in the presence of polyelectrolyte poly-(sodium 4-styrene-sulfate) (PSSS) were carefully investigated. The results showed that the ethanol volume content in the mixed solvent, temperature, the molar ratio of [CO3 2−]/[Ca2+] (R), and the concentrations of PSSS and CaCO3 turned out to be important parameters for the control of morphologies and polymorphs of CaCO3. Various morphologies of CaCO3 particles, such as rhombohedras, cubes, flowers, spheres, pancakes, etc. could be obtained dependent on the experimental conditions. Especially, monodispersed spheroid vaterite particles were obtained at the concentration of CaCO3 of 4mM. In addition, pancake-like vaterite particles were synthesized at 100°C. This research may provide a promising route for the selective synthesis of other inorganic materials with different morphologies and polymorphs. [Copyright &y& Elsevier]

Abstract: Novel dendrite-like SnS particles were synthesized for the first time by a facile solvothermal method based on the reaction between tin dichloride dihydrate (SnCl2·2H2O) and thiourea (Tu) in a mixed solvent of ethylenediamine (En) and dodecanethiol (De) at 200°C for 24h. The as-prepared products were characterized by X-ray diffraction and scanning electron microscopy (SEM). The experimental results showed that the concentration of SnCl2·2H2O and the relative volume ratios of En to De played important roles in the formation of unusual dendrite-like SnS architectures. On the basis of the experimental results, it was concluded that the formation of dendrite-like SnS particles was due to the oscillation of the concentration of Sn2+ ions at the vicinity of the growing surfaces, and the consequent periodic growth of the crystals. [Copyright &y& Elsevier]

Abstract: SnO2/TiO2 composite films were fabricated on transparent electro-conductive glass substrates (F-doped SnO2-coated glass:FTO glass) via an electrophoretic deposition (EPD) method using Degussa P25 as raw materials, and were further characterized by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), field emission scanning electron microscope (FESEM), UV–vis diffuse reflectance spectra and Photoluminescence spectra (PL). XRD and XPS results confirmed that the films were composed of TiO2 and SnO2. FESEM images indicated that the as-prepared TiO2 films had roughness surfaces, which consisted of nano-sized particles. The effects of calcination temperatures on the surface morphology, microstructures and photocatalytic activity of SnO2/TiO2 composite films were further investigated. All the prepared SnO2/TiO2 composite films exhibited high photocatalytic activities for photocatalytic decolorization of Rhodamine-B aqueous solution. At 400°C, the SnO2/TiO2 composite films showed the highest photocatalytic activity due to synergetic effects of low sodium content, good crystallization, appropriate phase composition and slower recombination rate of photogenerated charge carriers. [Copyright &y& Elsevier]

Abstract: Novel flower-like α-manganese sulfide (MnS) particles are solvothermally synthesized via a precipitation reaction of manganese dichloride (MnCl2) and thiourea (Tu) in ethylene glycol (Eg) solvent at 180°C for 24h. The as-prepared products are characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), and transmission electron microscopy (TEM). The influences of experimental parameters, including reaction temperatures and time, molar ratio R of MnCl2 to Tu, and solvents on the morphologies of the products were investigated. It was found that appropriate experimental conditions were crucial for the formation of unusual flower-shaped α-MnS particles. Various crystal morphologies, such as flowers, spheres, and polyhedrons could be fabricated by changing the experimental conditions. A possible formation mechanism was proposed to explain the formation of novel flower-like α-MnS particles. [Copyright &y& Elsevier]

Abstract: Crystalline bi-phase TiO2 hollow microspheres with mesoporous shells are one-pot fabricated by hydrothermal treatment of acidic (NH4)2TiF6 aqueous solution in the presence of glucose at 180°C for 24h, and then calcined at different temperatures for 4h. The as-prepared samples are characterized by XRD, SEM, TEM and nitrogen adsorption–desorption isotherms. The photocatalytic activity of the as-prepared samples is evaluated by photocatalytic decolorization of methyl orange aqueous solution at ambient temperature. The results indicate that the prepared TiO2 samples possess a bimodal pore size distribution in the mesoporous region. At 500°C, TiO2 hollow microspheres exhibit the highest photocatalytic activity probably due to an optimal mass ratio of rutile to anatase. [Copyright &y& Elsevier]

Abstract: A simple method for preparing highly daylight-induced photoactive nanocrystalline C,N,S-tridoped TiO2 powders was developed by a solid-phase reaction. The as-prepared TiO2 powders were characterized by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), UV–vis diffuse reflectance spectra, N2 adsorption–desorption measurements and transmission electron microscopy (TEM). The photocatalytic activity was evaluated by the photocatalytic oxidation of formaldehyde under daylight irradiation in air. The results show that daylight-induced photocatalytic activities of the as-prepared TiO2 powders were improved by C,N,S-tridoping. The C,N,S-tridoped TiO2 powders exhibited stronger absorption in the near UV and visible-light region with red shift in the band-gap transition. When the molar ratio of CS(NH2)2 to xerogel TiO2 powders (prepared by hydrolysis of Ti(OC4H9)4 in distilled water) (R) was kept in 3, the daylight-induced photocatalytic activities of the as-prepared C,N,S-tridoped TiO2 powders were about more than six times greater than that of Degussa P25 and un-doped TiO2 powders. The high activities of the C,N,S-tridoped TiO2 can be attributed to the results of the synergetic effects of strong absorption in the near UV and visible-light region, red shift in adsorption edge and two phase structures of un-doped TiO2 and C,N,S-tridoped TiO2. [Copyright &y& Elsevier]

Mesoporous titania nanorod/titanate nanotube composites were prepared using TiF4 and H3BO3 as the precursors. The prepared samples were characterized with TEM, SEM, XRD, HRTEM, and nitrogen adsorption–desorption isotherms. The photocatalytic activities were evaluated by photocatalytic oxidation of acetone in a gas phase and photocatalytic discolorization of methyl orange aqueous solution in an aqueous phase, respectively. The results indicated that the photocatalytic activity of the mesoporous titania nanorod/titanate nanotube composites exceeded that of P25 by a factor of about 2.5 times for the photocatalytic oxidation of acetone. This could be attributed to the fact that the former had a larger specific surface area and a higher pore volume. Moreover, the mesoporous titania nanorod/titanate nanotube composites, which could be readily separated after photocatalytic reaction in an aqueous phase, exhibited highly photocatalytic activity for the degradation of methyl orange aqueous solution. [Copyright &y& Elsevier]

Abstract: Ternary single-crystalline NaV6O15 nanoneedles were synthesized on a large scale by a novel in situ reaction–crystallization–etching process using bulk V2O5 powders and poly(styrene-alt-maleic acid) sodium salt (PSMA-Na) as raw materials and HF as a catalyst under hydrothermal treatment at 180°C for 24h. HF not only catalyzes the formation of NaV6O15 nanowires but also promotes the transition of nanowires to nanoneedles. The synthesized nanostructures appeared needle-shaped, with sharp tips about 3–50nm in diameter and wide butts of tens to 250nm at the other end, while the lengths of the nanoneedles normally ranged from 5 to ∼20μm. [Copyright &y& Elsevier]

Abstract: The morphogenesis of copper oxalate polycrystalline pitted and patterned tablets were investigated in a simple precipitation reaction between copper sulfate and oxalic acid solutions. The formation of the pit or pattern on the surfaces of the tablets could be related to an etching or partial dissolution process at the central region of the tablets during aging. The presence of poly(ethylene glycol) (PEG), acidity of the reaction mixture and temperature exhibited significant effect on the morphology of the products, which could be rationally associated with different etching processes under different conditions. [Copyright &y& Elsevier]

Abstract: Hierarchical pagodas and monodispersed quasi-octahedrons of lead tungstate (PbWO4) have been controllably synthesized through an easy mineralization process of preformed PbWO4 suspension under natural conditions. The selective synthesis of PbWO4 pagodas and quasi-octahedrons is achieved in the absence or presence of mixed organic additive polyvinylpyrrolidone and cetyltrimethylammonium bromide. X-ray powder diffraction, scanning electron microscopy, transmission electron microscopy, high-resolution transmission electron microscopy, and Fourier transformation infrared spectroscopy have been used to characterize the obtained PbWO4 products. It is demonstrated that the cooperative effect of polyvinylpyrrolidone and cetyltrimethylammonium bromide is responsible for the morphological transformation of PbWO4 crystals from pagodas to quasi-octahedrons. [Copyright &y& Elsevier]

Hydrogen titanate (H-titanate) nanowires were prepared via a hydrothermal reaction of TiO2 powders (P25) in KOH solutions and then calcined at various temperatures. The phase structure, crystallite size, morphology, specific surface area, and pore structures of the calcined H-titanate nanowires at various temperatures were characterized with field emission scanning electron microscope, X-ray diffraction, transmission electron microscopy and nitrogen adsorption–desorption isotherms, and their photocatalytic activities were evaluated by photocatalytic oxidation of acetone in air. With increasing calcination temperature, the specific surface area and porosity of the calcined samples steadily decreased. At a calcination temperature range of 400–600°C, the calcined H-titanate nanowires showed higher photocatalytic activity than P25 powders for photocatalytic oxidation of acetone. Especially, at 500°C, the calcined H-titanate nanowires showed the highest photocatalytic activity, which exceeded that of P25 by a factor of about 1.8 times. This can be attributed to the synergetic effect of larger specific surface area, higher pore volume and the presence of brookite TiO2. With further increase in the calcination temperature (700–900°C), the photocatalytic activity of the samples decreased obviously owing to the growth of TiO2 crystallites. [Copyright &y& Elsevier]

Abstract: The novel starlike PbS particles were successfully synthesized for the first time in a mixed system of poly-(styrene-alt-maleic acid) (PSMA) and cetyltrimethylammonium bromide (CTAB). The as-prepared hierarchically starlike PbS particles have six symmetric perpendicular arms or arm groups, each of which consists of parallel rods or ellipsoids that are perpendicular to the arm. Moreover, spherical and cubic-shaped PbS particles were facilely produced via varying the concentration of CTAB in the mixed system. The presence of CTAB in the mixed system played a key role in the formation of unusual PbS stars. The faster growth rate in six 〈100〉 directions of PbS crystals induced by the organic additives were thought to be responsible for the formation of such novel starlike PbS particles. [Copyright &y& Elsevier]

Abstract: Bimodal nanocrystalline mesoporous TiO2 powders with high photocatalytic activity were prepared by a hydrothermal method using tetrabutylorthotitanate (TiO(C4H9)4, TBOT) as precursor. The as-prepared TiO2 powders were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and high-resolution transmission electron microscopy (HRTEM), X-ray photoelectron spectroscopy (XPS) and N2 adsorption–desorption measurements. The photocatalytic activity of the as-prepared TiO2 powders was evaluated by the photocatalytic degradation of acetone (CH3COCH3) under UV-light irradiation at room temperature in air. The effects of hydrothermal temperature and time on the microstructures and photocatalytic activity of the TiO2 powders were investigated and discussed. It was found that hydrothermal treatment enhanced the phase transformation of the TiO2 powders from amorphous to anatase and crystallization of anatase. All TiO2 powders after hydrothermal treatment showed bimodal pore-size distributions in the mesoporous region: one was intra-aggregated pores with maximum pore diameters of ca. 4–8nm and the other with inter-aggregated pores with maximum pore diameters of ca. 45–50nm. With increasing hydrothermal temperature and time, the average crystallite size and average pore size increased, in contrast, the Brunauer-Emmett-Teller (BET) specific surface areas, pore volumes and porosity steadily decreased. An optimal hydrothermal condition (180°C for 10h) was determined. The photocatalytic activity of the prepared TiO2 powders under optimal hydrothermal conditions was more than three times higher than that of Degussa P25. [Copyright &y& Elsevier]

Abstract: The nanocomposites of one-dimensional (1D) titanate nanotubes and 0D rutile nanocrystals were fabricated by hydrothermal treatment of bulky rutile TiO2 powders in a 10M NaOH solution without using any templates and catalysts. The as-prepared samples were characterized with transmission electron microscopy (TEM), high-resolution transmission electron microscopy (HRTEM), X-ray diffraction (XRD), Brunauer–Emmett–Teller (BET) surface area, Fourier transform infrared spectroscopy (FTIR), UV–visible spectrophotometry (UV–vis), Raman spectroscopy and X-ray photoelectron spectroscopy (XPS). It was found that many small rutile nanocrystal particles of about 5nm could uniformly attach to the outer surface and in the inner of the titanate nanotubes, forming an interesting and novel nanocomposite structure. Adjusting reaction time could control the amount of rutile nanoparticles in the nanocomposites. With increasing reaction time, the specific surface areas, porosity, pore volume, UV absorption and band gap energies of the nanocomposites gradually increased due to the fact that rutile particles were steadily turned into the tubular nanocomposites, finally completely formed titanate nanotubes. [Copyright &y& Elsevier]

Abstract: Na-free anatase TiO2 film was prepared on soda-lime glass (SL-glass) from a TiF4 aqueous solution upon addition of boric acid at 60°C. It was found that the as-prepared TiO2 film before calcination showed a higher photocatalytic activity than the calcined sample (500°C). This could be attributed to the fact that the calcined TiO2 film contained decent Na+ ions, which was diffused from the SL-glass substrate into the TiO2 film during calcination, resulting in the decrease of photocatalytic activity. [Copyright &y& Elsevier]

Abstract: Highly photoactive nanocrystalline mesoporous Fe-doped TiO2 powders were prepared by the ultrasonic-induced hydrolysis reaction of tetrabutyl titanate (Ti(OC4H9)4) in a ferric nitrate aqueous solution (pH 5) without using any templates or surfactants. The as-prepared samples were characterized by thermogravimetry and differential thermal analysis (TG-DTA), X-ray diffraction (XRD), N2 adsorption–desorption measurements, UV–visible adsorbance spectra (UV–vis) and X-ray photoelectron spectroscopy (XPS). The photocatalytic activities were evaluated by the photocatalytic oxidation of acetone in air. The results showed that all the Fe-doped TiO2 samples prepared by ultrasonic methods were mesoporous nanocrystalline. A small amount of Fe3+ ions in TiO2 powders could obviously enhance their photocatalytic activity. The photocatalytic activity of Fe-doped TiO2 powders prepared by this method and calcined at 400°C exceeded that of Degussa P25 (P25) by a factor of more than two times at an optimal atomic ratio of Fe to Ti of 0.25. The high activities of the Fe-doped TiO2 powders could be attributed to the results of the synergetic effects of Fe-doping, large BET specific surface area and small crystallite size. [Copyright &y& Elsevier]

Abstract: Highly photoactive nano-sized TiO2 powder photocatalyst was prepared by a hydrothermal method at 180°C for 5h using tetrabutyl titanate (TBOT) as the precursor. The pH values of the starting suspensions were adjusted from 1 to 11 using a 1.0M HCl or 1.0M NH3·H2O solution. The obtained TiO2 powders were characterized with X-ray diffraction (XRD), N2 adsorption–desorption measurement, transmission electron microscopy (TEM), X-ray photoelectron spectra, Fourier transform infrared (FTIR), Raman spectra and UV–vis spectrophotometry. The photocatalytic activity was evaluated by photocatalytic oxidation decomposition of acetone in air. The results showed that the pH values of the solutions obviously influenced the microstructures and photocatalytic activity of the as-prepared TiO2 powders. With increasing pH values, the crystallization enhanced, crystallite size increased and BET specific surface areas decreased. The photocatalytic activity of TiO2 powders prepared at a pH range of 6–9 exceeded that of Degussa P-25 by a factor of more than two times. [Copyright &y& Elsevier]

Abstract: Mesoporous anatase TiO2 nanofibers were prepared by a simple hydrothermal post-treatment of titanate nanotubes. The as-prepared samples were characterized with transmission electron microscopy (TEM), thermogravimetry (TG), X-ray diffraction (XRD), field emission scanning electron microscope (FESEM), and N2 adsorption–desorption measurement. The photocatalytic activity of the mesoporous TiO2 nanofibers was evaluated by photocatalytic oxidation of acetone in air. The effects of hydrothermal post-treatment time on the structures and photocatalytic activity of the mesoporous TiO2 nanofibers were discussed. The results showed that the photocatalytic activity of the TiO2 nanofibers prepared by this method exceeded that of Degussa P25 when the hydrothermal post-treatment time was kept at 200°C for 3–24h. This could be attributed to the fact that the former had smaller crystallite size, larger specific surface area, and higher pore volume. [Copyright &y& Elsevier]

Abstract: TiO2 powder (P25) was hydrothermally treated in pure water at 150°C for different times. The P25 powders before and after hydrothermal treatment were characterized with XRD, TEM, UV–vis, XPS and nitrogen adsorption–desorption isotherms. The results showed that a small amount of anatase was transformed into rutile phase and more aggregates of the TiO2 crystallites formed after hydrothermal treatment, resulting in the decrease of specific surface area of the TiO2 powders. The photocatalytic activity of the hydrothermally treated P25 powders was obviously higher than that of the P25 powder. This can be attributed to the formation of more hydroxyl groups in the surface of TiO2. The more hydroxyl groups would generate more hydroxyl radicals, enhance the adsorption of O2 molecules and reduce recombination of the photogenerated electrons and holes. Moreover, more hydroxyl was also beneficial to the activation of the rutile phase, leading to an enhanced photocatalytic activity. [Copyright &y& Elsevier]

Abstract: Anatase TiO2 nanoparticles were uniformly coated on the surface of the titanate nanorods using TiF4 and H3BO3 as the precursors via a simple solution route. The prepared samples were characterized with SEM, XRD, TEM, HRTEM and nitrogen adsorption–desorption isotherms and their photocatalytic activities were evaluated by photocatalytic decolorization of methyl orange aqueous solution. The effects of the precursor concentration, deposition time and deposition temperature on the morphology and phase structure of the TiO2 nanoparticle-coated titanate nanorods were investigated. Compared with the titanate nanorods, the novel TiO2 nanoparticle-coated titanate nanorods showed an obvious increase in the specific surface area and pore volume due to the formation of TiO2 nanoparticles (10–50nm) on the surface of the titanate nanorods. Moreover, the TiO2 nanoparticle-coated titanate nanorods, which could be readily separated after photocatalytic reaction, exhibited highly photocatalytic activity for the degradation of methyl orange aqueous solution. [Copyright &y& Elsevier]

Abstract: Titanate nanotubes were prepared via a hydrothermal treatment of TiO2 powders (P25) in a 10M NaOH solution at 150°C for 48h and then calcined at various temperatures. The as-prepared titanate nanotubes before and after calcination were characterized with XRD, TEM, HRTEM, SEM, FESEM, and nitrogen adsorption–desorption isotherms. The photocatalytic activity of the as-prepared samples was evaluated by photocatalytic oxidation of acetone in air. The effects of calcination temperature on the phase structure, crystallite size, morphology, specific surface area, pore structures and photocatalytic activity of the titanate nanotubes were investigated. The results indicated that at 400 to 600°C, the calcined nanotube samples showed a higher photocatalytic activity than Degussa P25. Especially, at 400 and 500°C, the photocatalytic activity of the calcined nanotubes exceeded that of P25 by a factor of about 3.0 times. This could be attributed to the fact that the former had a larger specific surface area and pore volume. With further increase in the calcination temperature from 700 to 900°C, the photocatalytic activity of the calcined nanotube samples greatly decreased due to the formation of rutile phase, the sintering and growth of TiO2 crystallites and the decrease of specific surface area and pore volume. [Copyright &y& Elsevier]

Abstract: Monodispersed nanoporous SiO2/TiO2 composite microspheres with high specific surface areas were prepared by depositing titania colloid particles on the surface of monodispersed microporous silica microspheres using a simple electrostatic attraction strategy, and then calcined at 600°C for 4h. The as-prepared products were characterized with differential thermal analysis and thermogravimetric (DTA/TG), scanning electron microscopy (SEM), X-ray diffraction (XRD), nitrogen adsorption and X-ray photoelectron spectroscopy (XPS). It was found that uniform titania coatings could be deposited on the surface of silica microspheres by adjusting the pH value of the reaction solution to an optimal pH value ranges of about 4–5. The specific surface area and pore volume of the SiO2/TiO2 composite microspheres calcined at 600°C were 960m2 g−1 and 0.48mLg−1, respectively. [Copyright &y& Elsevier]

Abstract: A simple method for preparing highly photoactive nanocrystalline mesoporous N,S-codoped TiO2 powders was developed by hydrolysis of Ti(SO4)2 in a NH3·H2O solution at room temperature. The as-prepared TiO2 powders were characterized with X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), thermalgravimetric and differential thermal analysis (TG–DTA), UV–vis diffuse reflectance spectra, N2 adsorption–desorption measurements, scanning electron microscope (SEM) and transmission electron microscopy (TEM). The photocatalytic activity was evaluated for the photocatalytic oxidation of acetone and formaldehyde under UV light and daylight irradiation in air, respectively. The results showed that the as-prepared TiO2 powders exhibited a stronger absorption in the UV–vis light region and a red shift in the band gap transition due to N,S-codoping. The photocatalytic activity of the as-prepared N,S-codoped TiO2 powders at a temperature range of 400–700°C were obviously higher than that of commercial Degussa P25. Especially, the daylight-induced photocatalytic activities of the as-prepared N,S-codoped TiO2 powders were about ten times greater than that of Degussa P25. The high activities of the N,S-codoped TiO2 can be attributed to the results of the synergetic effects of strong absorption in the UV–vis light region, red shift in adsorption edge, good crystallization, large surface area and two phase structures of undoped TiO2 and N,S-codoped TiO2. [Copyright &y& Elsevier]