Facile Homogeneous Precipitation Method Research Articles

Facile assembly of Au nanoparticles modified hierarchical mesoporous In2O3 for highly sensitive ethanol gas detection

Flower-like In(OH)3 was synthesized by a facile homogeneous precipitation method and subsequently calcined at 300 °C to prepare nanosheets assembled 3D flower-like mesoporous In2O3, which was then modified with Au nanoparticles via sol-immobilization method to produce 3D hierarchical mesoporous Au/In2O3 for ethanol detection. The as-prepared Au/In2O3 were carefully characterized by XRD, SEM, HRTEM and XPS techniques. The flower-like structure was assembled by many ultrathin coarse mesoporous In2O3 nanosheets, and Au nanoparticles with an average size of 3.3 nm were evenly dispersed on In2O3 nanosheets. The 3D flower-like mesoporous 1%Au/In2O3 has a high specific surface area of about 130 m2 g−1 and shows the best sensitivity to ethanol among the flower-like mesoporous Au/In2O3 materials. It can sensitively detect ethanol gas at a relatively low temperature of 160 °C with a response of 115–50 ppm ethanol, increased by nearly 11 times compared to In2O3 at 210 °C. The 3D flower-like mesoporous 1%Au/In2O3 also has good selectivity to ethanol with response about 9.4, 26.1, 20.9 and 29.5 times higher than that to acetone, methanol, toluene and xylene, and it displays excellent linear relationship between the response and the ethanol concentration. The markedly improved sensitivity and selectivity of the 3D flower-like mesoporous 1%Au/In2O3 results from both the electronic sensitization and chemical sensitization effects of Au nanoparticles. In short, the 3D flower-like mesoporous 1%Au/In2O3 possesses excellent sensitivity, selectivity, repeatability, linear relationship and long-term stability at 160 °C. Therefore, the obtained 3D flower-like mesoporous 1%Au/In2O3 has great potential for ethanol gas detection.

Facile homogeneous precipitation method to prepare MnO2 with high performance in catalytic oxidation of ethyl acetate

Altering the urea decomposition rate in the homogeneous precipitation progress enabled the formation of various morphologies of α-MnO 2 . The decrease in crystalline size led to an increase in the surface area and dominance of the (2 1 1) crystal plane. The abundant surface oxygen species and high reducibility related to unsaturated manganese played critical roles in the decomposition of ethyl acetate. • A facile method driven by a synchronous reaction of urea hydrolysis and potassium permanganate reduction was proposed. • Pure α-MnO 2 with various morphologies was obtained by tuning reaction parameters. • Oxygen species on the (2 1 1) crystal plane were found to be most active in oxidation. • The optimal α-MnO 2 catalyst exhibited high and stable catalytic performance. A facile homogeneous precipitation method driven by synchronous reactions of urea hydrolysis and potassium permanganate reduction is proposed for preparation of MnO 2 catalysts. Pure α-MnO 2 nanostructures with different morphologies, including nanowires, nanorods and nanoparticles, were obtained by simply tuning the precipitation conditions. The evolution of materials derived from different preparation conditions was investigated via X-ray diffraction, transmission electron microscopy, N 2 adsorption, X-ray photoelectron spectroscopy, chemisorption and DFT calculations. The precipitation temperature and time significantly influenced the physiochemical properties of as-prepared catalysts. With increasing precipitation temperature and time, the degree of crystallinity, BET surface area and amount of surface-adsorbed oxygen of α-MnO 2 exhibited a substantial increase. The main exposed surface facets varied from (2 0 0), (3 1 0) to (2 1 1) as temperature and time increased. The best precipitation temperature and time were 90 °C and 24 h respectively. The optimal α-MnO 2 catalyst demonstrated 100% conversion of 1000 ppm ethyl acetate under the high space velocity of 78,000 h −1 during a 113-h test at 190 °C, outperforming other manganese oxide catalysts and many typical noble metal catalysts in terms of activity and stability. Experimental results and DFT calculations were consistent and indicated that surface oxygen species originating from the (2 1 1) surface of α-MnO 2 were most active. This study provides important insights for manipulating the morphology of MnO 2 by a facile method and remarkably promoting the performance for ethyl acetate VOC elimination.

Electrochemical property of hierarchical flower-like α-Ni(OH)2 as an anode material for lithium-ion batteries

Transition metal hydroxides (TMHs) are recently receiving increasing attention as anode materials for lithium-ion batteries (LIBs) because of their merits of high theoretical capacity, low cost, and easy preparation. Herein, hierarchical flower-like α-Ni(OH)2 is synthesized by a facile homogeneous precipitation method with Ni(NO3)2·6H2O and urea as raw materials. When evaluated as an anode material for lithium-ion batteries, the α-Ni(OH)2 delivers a high reversible capacity of 1346 mA h g−1 at a current density of 0.05 A g−1, and gives a reversible capacity of 475 mA h g−1 at a high current density of 5.0 A g−1. It maintains a reversible capacity of 1227 mA h g−1 after 30 cycles at 0.1 A g−1, with a capacity retention of 97.0% compared to the second cycle. The charge storage mechanism and kinetics of the α-Ni(OH)2 are analyzed by sweep voltammetry method and electrochemical impedance spectroscopy. The results demonstrate that the lithium ion storage process in the α-Ni(OH)2 is mainly dominated by pseudocapacitive behavior, which is responsible for the superior rate capability; the charge-transfer resistance of the α-Ni(OH)2 is sensitive to the state of charge; the apparent lithium ion diffusion coefficient of the α-Ni(OH)2 varies in the range of 10−14–10−15 cm2 s−1.

Synthesis, characterization and formation mechanism of pompon-like Lu2O2SO4: Eu3+ phosphors via a facile homogeneous precipitation method followed by calcination

A series of Eu3+ doped pompon-like Lu2O2SO4 phosphors with diameter of ~800 nm have been synthesized by commercial available lutetium oxide (Lu2O3), nitric acid (HNO3), europium nitrate (Eu(NO3)3·6H2O), urea (CO(NH2)2), ammonium sulfate ((NH4)2SO4) and ammonia (NH3·H2O) as the starting materials via a facile homogeneous precipitation method followed by a subsequent calcination process. The as-prepared products were well characterized by X-ray powder diffraction (XRD), thermogravimetry and differential scanning calorimeter (TG-DSC), flourier transform infrared spectra (FT-IR), field emission scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM), and photoluminescence (PL) spectra. Studies have shown that the molar ratio of Lu3+:(NH4)2SO4:CO(NH2)2 is very important in the homogeneous precipitation process, and the optimal ratio is selected as 1:25:50. In the subsequent calcination process, the effect of calcination temperature on the target product was studied and the optimal calcination condition is the calcination temperature of 800 °C for 2 h in air. And the morphology mechanism of the pompon-like Lu2O2SO4 is explored, detailed investigation showed the formation of pompon structure is accompanied by two different growth mechanisms. According to PL spectra, under 396 nm ultraviolet (UV) light excitation, the strongest emission peak for the Lu2O2SO4:x%Eu3+ phosphors located at 620 nm, which corresponds to the typical 5D0-7F2 transition of Eu3+ ions. The optimal doping concentration of Eu3+ ions in the Lu2O2SO4 host lattice is 6.0%, whose average lifetime τ and color correlation temperature (CCT) are calculated to be 39.558 μs and 1915 K, respectively.

Ultrasensitive SO2 sensor for sub-ppm detection using Cu-doped SnO2 nanosheet arrays directly grown on chip

Ultrasensitive trace detection of toxic and harmful gases has become an important research field with increasing of human needs. This work introduces a chemiresistive type of SO2 sensor based on Cu-doped SnO2 nanosheet arrays (Cu-SnO2 NSAs), which are directly grown on the chip of Au electrodes via a facile homogeneous precipitation method. The vertically-aligned Cu-SnO2 nanosheets with ultrathin thickness (<10 nm) feature a cross-linked structure and semi-open space among these nanosheets. Compared with pure SnO2 NSAs, the Cu-doped (1–5%, molar percent) sensors exhibit significantly improved SO2 detection capability even at sub-ppm level in a dry environment, where SO2 acts as a stronger oxidizing agent than oxygen. In particular, the 1% Cu-SnO2 NSAs show the highest response (91.51, at 6 ppm) and good selectivity toward SO2 gas at an operation temperature of 250 °C, suggesting a promising route to the development of ultrasensitive SO2 sensors. Furthermore, the effects of environment humidity and operation temperature on the SO2 sensing properties of Cu-SnO2 NSAs are investigated.

Preparation of petal-particle cross-linking flowerlike NiO for supercapacitor application

Abstract In this work, flowerlike NiO is successfully prepared via a facile homogeneous precipitation method using different surfactants as templates in water/ethanol solution. And the flowerlike NiO using sodium dodecyl sulfate as surfactant possesses larger specific surface area (188.3 m2/g) and better electrochemical performance. The electrochemical property of NiO is further optimized through changing the ratios of water and ethanol and the material delivers high specific capacitance (631.7 F/g at 1 A/g) and excellent durability (82.8% capacitance retention after 5000 cycles at 10 A/g) when the ratio of water/ethanol is 3:1. The characterizations confirm that the outstanding performance of this material derives from the petal-particle cross-linking flowerlike structure of NiO. The possible formation mechanism is proposed. This work provides a novel method for preparing NiO electrode material with high performance supercapacitor.

Novel CeMnaOx catalyst for highly efficient catalytic decomposition of ozone

Novel CeMnaOx (a is the molar ratio of Mn to Ce) catalysts for catalytic decomposition of ozone (O3) under high GHSV conditions were successfully synthesized by a facile homogeneous precipitation method. CeMn10Ox showed ozone conversion of 96 % for 40 ppm O3 under relative humidity (RH) of 65 % and space velocity of 840 L·g−1 ·h-1 after 6 h at room temperature, which is far superior to the performance of the α-Mn2O3 (38 %). The ozone decomposition activity of α-Mn2O3 increased by a factor of 2.5 with the addition of Ce. XRD, XPS, H2-TPR, O2-TPD, EXAFS and DFT calculations data confirmed that cerium-manganese complex oxides with enhanced surface area were formed, which played a key role in the decomposition of ozone. This study provides important insights for developing improved catalysts for gaseous ozone decomposition that can be prepared by a simple method, and promoting the performance of manganese oxides for practical ozone elimination.

Facile preparation of α-Ni(OH)2/graphene nanosheet composite as a cathode material for alkaline secondary batteries

α-Ni(OH)2 has attracted great attention as a cathode material for alkaline secondary batteries (ASBs) because of its high theoretical capacity and small volume change during charge/discharge cycles. However, poor cycling stability and low electronic conductivity of α-Ni(OH)2 severely hinder its development and practical applications in ASBs. In this work, α-Ni(OH)2/graphene nanosheet composite was successfully fabricated by a facile homogeneous precipitation method. The nanocomposite is composed of α-Ni(OH)2 nanoflowers decorated homogeneously on the surfaces of graphene nanosheets. When evaluated as cathode material for ASBs, this α-Ni(OH)2/graphene nanocomposite exhibits much enhanced high-rate capability and cycling stability compared to the pure α-Ni(OH)2 due to the improved electrochemical reaction kinetic, enhanced electronic conductivity, and hierarchical nanostructure. For example, the α-Ni(OH)2/graphene nanocomposite presents a rate retention of 74.8% as the current density increasing from 250 to 5000 mA g−1, much higher than that (49.0%) of pure α-Ni(OH)2; moreover, at a current density of 2000 mA g−1, the α-Ni(OH)2/graphene nanocomposite still maintains a reversible capacity of 177 mA h g−1 after 200 cycles, which is four times higher than that (41 mA h g−1) of the pure α-Ni(OH)2. The attractive electrochemical performances and facile synthesis route made the prepared α-Ni(OH)2/graphene nanocomposite become a promising electrode material for ASBs.

Uniform and Well-Dispersed LuBO₃ Hollow Microspheres: Synthesis, Formation and Photoluminescence Properties.

A hard template strategy is developed to fabricate the LuBO3: Eu3+/Tb3+ hollow microspheres using a novel multi-step transformation synthetic route for the first time with polystyrene (PS) spheres as the template, followed by the combination of a facile homogeneous precipitation method, an ion-exchange process, and a calcination process. The results show that the as-obtained LuBO3: Eu3+/Tb3+ hollow spheres have a uniform morphology with an average diameter of 1.8 μm and shell thickness of about 80 nm. When used as luminescent materials, the emission colors of LuBO3: Eu3+/Tb3+ samples can be tuned from red, through orange, yellow and green-yellow, to green by simply adjusting the relative doping concentrations of the activator ions under the excitation of ultraviolet (UV) light, which might have potential applications in the field such as light display systems and optoelectronic devices.

Room-temperature fabrication of bismuth oxybromide/oxyiodide photocatalyst and efficient degradation of phenolic pollutants under visible light

Bismuth oxybromide/oxyiodide (Bi4O5BrxI2-x) photocatalysts were successfully fabricated using a facile homogeneous precipitation method at room temperature. The obtained Bi4O5BrxI2-x demonstrated highly enhanced visible-light performances compared with Bi4O5Br2 and Bi4O5I2. The poducts were characterized by X-ray diffraction (XRD), UV–vis diffuse reflectance spectra (DRS), X-ray photoelectron spectroscopy (XPS), scanning electron microscope (SEM), and transmission electron microscope (TEM). The DRS analysis shows that the band gap structures of Bi4O5BrxI2-x have been gradually modulated by changing the Br/I molar ratio. The obtained Bi4O5BrxI2-x samples have exhibited efficient photocatalytic activities in decomposing resorcinol, o-phenylphenol, and 4-tert-butylphenol. The Br/I molar ratio has great influence on the activity of the photocatalysts, and Bi4O5Br0.6I1.4 exhibited the best activity which was about 2.77 and 1.80 times higher than that of Bi4O5Br2 and Bi4O5I2, respectively. The degradation intermediates were identified by liquid chromatography-mass spectrometry (LCMS), and the possible degradation pathway of resorcinol over Bi4O5BrxI2-x photocatalysts was proposed. The strong visible light absorption, high charge separation efficiency, and proper band potentials should be responsible for the excellent activity of Bi4O5BrxI2-x photocatalyst. Trapping experiments using radical scavengers confirmed the generation of O2−, OH, and h+, but only O2− and h+ have played the chief role in removing organic pollutants from water.

Enabling redox chemistry with hierarchically designed bilayered nanoarchitectures for pouch-type hybrid supercapacitors: A sunlight-driven rechargeable energy storage system to portable electronics

An essential key to enhance the redox chemistry of battery-type materials is to construct rational design of nanoarchitectures with high electrochemical activity. Herein, we reported a hierarchical composite consisting of bilayered nickel hydroxide carbonate nanoplates-decorated nanoflowers on nickel foam (NHC NPs@NFs/Ni foam) via a facile homogeneous precipitation method for use as an effective cathode in hybrid supercapacitors (HSCs). Under controlled growth time (4 h), the bilayered NHC NPs@NFs with hierarchical alignment were spontaneously crystallized on Ni foam. The as-preapared hybrid structure greatly enhanced the electroactive surface area and enabled the rapid redox chemistry in alkaline electrolyte. Notably, the hybrid NHC NPs@NFs/Ni foam delivered a maximum areal capacity of 727.4 μAh/cm2 at 2 mA/cm2 and it is relatively higher than its oxide form (76.6 μAh/cm2) in a three-electrode system. Also, a pouch-type HSC with bilayered NHC NPs@NFs/Ni foam and porous carbon electrodes was fabricated, which demonstrated superior energy storage performance in terms of capacitance (1445.8 mF/cm2), energy density (0.506 mWh/cm2), power density (35.675 mW/cm2) and cycling stability (89.4%). Furthermore, the self-charging power station consisting of a solar cell for energy conversion and the HSCs for energy storage was also assembled to operate the portable electronic displays and wall clock effectively for long time. This facile approach for the cost-effective fabrication of hierarchically designed nanomaterials paves a path for the development of high-performance hybrid supercapacitors.

Antioil Ag3PO4 Nanoparticle/Polydopamine/Al2O3 Sandwich Structure for Complex Wastewater Treatment: Dynamic Catalysis under Natural Light

We have successfully fabricated sandwich structural Ag3PO4 nanoparticle/polydopamine/Al2O3 porous small balls (APPAOs) by a facile homogeneous precipitation method, which exhibit a natural light catalysis capacity to degrade different kinds of water pollutants including industrial dyes and agricultural pesticides. The porous Al2O3 provides the substrate to form the Ag3PO4/Al2O3 heterojunction, as well as increases the specific surface area (SSA) of the Ag3PO4 nanoparticle, thus greatly enhancing the photocatalytic capacity. Polydopamine (PDA) plays the role of adhesive between Al2O3 substrate and Ag3PO4 nanoparticle, aiming to stabilize the synthesized APPAO catalyst. A part of Ag3PO4 is reduced by PDA and transformed into a Ag nanosphere, which further increases SSA and enhances the catalytic ability of the material by the plasmonic effect. Further study shows that there is a dynamic process between catalysis and adsorption/desorption equilibrium; i.e., with the catalysis going ahead, the adsorption/deso...

Lithium Storage Performance of Zinc Ferrite Nanoparticle Synthesized with the Assistance of Triblock Copolymer P123.

The ZnFe2O4 samples with the triblock copolymer P123 (P123) additive quantity of 0 wt.%, 2 wt.%, 5 wt.%, 8 wt.% and 10 wt.% were prepared by a very facile homogeneous precipitation method followed by high temperature sintering. The microstructures of the prepared samples were analyzed by X-ray diffraction (XRD) and Field emission scanning electron microscopy (FESEM). The results revealed that the five prepared samples are all normal spinel zinc ferrite (ZnFe2O4); the sample with the P123 additive quantity of 8 wt.% has the smallest particle size among the five samples. The lithium storage performances of the prepared samples are characterized by cyclic voltammograms (CV), electrochemical impedance spectroscopy (EIS), and charge-discharge tests. The results demonstrated that adding proper amount of P123 can obviously improve the lithium storage performances of zinc ferrite spinel powder. But excessive P123 can induce the particle agglomerates so that the lithium storage performance of sample decays significantly. The ZnFe2O4 sample with the P123 additive quantity of 8 wt.% exhibited the highest electrochemical activity, the best rate performance, and superior cycling stability. For example, after 50 charge/discharge cycles under a current density of 120 mA g-1, the ZnFe2O4 sample with the P123 additive quantity of 8 wt.% can retain a specific discharge capacity of 468 mAh g-1, much higher than that of for the ZnFe2O4 sample with the P123 additive quantity of 0 wt.% (224 mAh g-1).

Facile Synthesis and Down-Conversion Emission of RE3+-Doped Lutetium Oxide Nanoparticles.

Lu2O3:RE3+ (RE3+ = Eu3+, Tb3+, Ho3+) nanoparticles have been successfully synthesized by a facile homogeneous precipitation method with subsequent sintering process. The crystal structure, morphology and luminescence properties of the as-prepared samples have been characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), Fourier transform infrared (FT-IR), thermogravimetric analysis (TGA), photoluminescence (PL) and cathodoluminescence (CL) spectra. Upon ultraviolet (UV) and low-voltage electron beam excitation, Lu2O3:RE3+ (RE3+ = Eu3+, Tb3+, Ho3+) nanoparticles show strong red (Eu3+,5D0 → 7F2), green (Tb3+,5D4 → 7F5), and green (Ho3+,5S2 → 5I8) emissions. They exhibit a good advantage of multicolor emissions in the visible region, and endow these kinds of materials with potential application in many fields, such as light display systems, optoelectronic devices and biological imaging.

Large-scale fabrication of porous YBO3 hollow microspheres with tunable photoluminescence.

Hollow lanthanide-doped compounds are some of the most popular materials for high-performance luminescent devices. However, it is challenging to find an approach that can fabricate large-scale and well-crystallized lanthanide-doped hollow structures and that is facile, efficient and of low cost. In this study, YBO3: Eu3+/Tb3+ hollow microspheres were fabricated by using a novel multi-step transformation synthetic route for the first time with polystyrene spheres as the template, followed by the combination of a facile homogeneous precipitation method, an ion-exchange process and a calcination process. The results show that the as-obtained YBO3: Eu3+/Tb3+ hollow spheres have a uniform morphology with an average diameter of 1.65 µm and shell thickness of about 160 nm. When used as luminescent materials, the emission colours of YBO3: Eu3+/Tb3+ samples can be tuned from red, through orange, yellow and green-yellow, to green by simply adjusting the relative doping concentrations of the activator ions under the excitation of ultraviolet light, which might have potential applications in fields such as light display systems and optoelectronic devices.

Large-scale synthesis and luminescence of GdPO4 hollow microspheres.

GdPO4 hollow microspheres were synthesized by using a novel multi-step transformation synthetic route for the first time with polystyrene (PS) spheres as the template, followed by the combination of a facile homogeneous precipitation method, an ion-exchange process, and a calcination process. The XRD results indicated that the GdPO4 hollow microspheres have a pure hexagonal phase. The SEM and TEM images confirmed that the as-obtained GdPO4 hollow spheres have a uniform morphology with an average diameter of 2.7 μm and shell thickness of about 150 nm. The up-conversion luminescence properties as well as the emission mechanisms of the GdPO4:Yb3+, Ln3+ (Ln3+ = Tm3+, Er3+ and Ho3+) hollow microspheres were systematically investigated, which show blue (Tm3+, 1G4 → 3H6), green (Er3+, 4S3/2, 2H11/2 → 4I15/2), and red (Ho3+, 5F5 → 5I8) luminescence under 980 nm NIR excitation, providing potential applications in bioanalysis, optoelectronic and nanoscale devices, future color displays and light-emitting devices, and so on.

Structure and lithium storage performances of nickel hydroxides synthesized with different nickel salts

Nickel hydroxides with hierarchical micro-nano structures are prepared by a facile homogeneous precipitation method with different nickel salts (Ni(NO3)2·6H2O, NiCl2·6H2O, and NiSO4·6H2O) as raw materials. The effect of nickel sources on the microstructure and lithium storage performance of the nickel hydroxides is studied. It is found that all the three prepared samples are α-nickel hydroxide. The nickel hydroxides synthesized with Ni(NO3)2·6H2 or NiCl2·6H2O show a similar particle size of 20–30 μm and are composed of very thin nano-sheets, while the nickel hydroxide synthesized with Ni(SO4)2·6H2O shows a larger particle size (30–50 μm) and consists of very thin nano-walls. When applied as anode materials for lithium-ion batteries (LIBs), the nickel hydroxide synthesized with NiSO4·6H2O exhibits the highest discharge capacity, but its cyclic stability is very poor. The nickel hydroxides synthesized with NiCl2·6H2O exhibit higher discharge capacity than the nickel hydroxides synthesized with Ni(NO3)2·6H2O, and both of them show much improved cyclic stability and rate capability as compared to the nickel hydroxide synthesized with Ni(SO4)2·6H2O. Moreover, pseudocapacitive behavior makes a great contribution to the electrochemical energy storage of the three samples. The discrepancies of lithium storage performance of the three samples are analyzed by ex-situ XRD, FT-IR, electrochemical impedance spectroscopy (EIS), and cyclic voltammetry (CV) tests.

Facile synthesis and characterization of ZnS nano/microcrystallites with enhanced photocatalytic activity

ZnS nano-microcrystallites with different size were controllably synthesized by a facile homogeneous precipitation method. The products were characterized by X-ray diffraction, field emission scanning electron microscopy, high resolution transmission electron microscopy, N2-sorption BET surface area and UV–vis diffused reflectance spectra for their morphology, size and optical performance. Results show that the crystallinity and size of the samples strongly depend on the Zn/S molar ratio of the precursor solution. Moreover, the electronic band structures of all samples were investigated relatively from the sides of theory and practice. The photocatalytic performances of the as-prepared ZnS samples were evaluated towards the removal of MO upon UV-light irradiation. The results indicate that the ZnS nanoparticles prepared at the Zn/S molar ratio of 1:2 exhibited the highest photocatalytic activity with the degradation ratio of 96.8% in 24min, which was mainly attributed to the high separation efficiency of electron and hole pairs and large surface area. With the help of scavengers, ·O2– was proved to be the main reactive species during the degradation.

Size dependent photocatalytic activity of ZnS nanostructures prepared by a facile precipitation method

Size-controlled ZnS nanostructures have been synthesized successfully with different reaction pH via a facile homogeneous precipitation method. These samples were characterized by X-ray diffraction, scanning electron microscopy (SEM), transmission electron microscopy (TEM), N2-sorption BET surface area, Raman spectra and UV–vis spectroscopy for their structures, morphologies, specific surface area and band gaps values (Eg). Results show that the size of the prepared nanospheres can be controllably tuned by adjusting pH value. Moreover, the size-related mechanism of different samples was also discussed. The degradation of methyl orange (MO) under UV light irradiation was carried out to study the effects of the size on the photocatalytic activity of the prepared samples. It was found that the sample obtained at pH=7 exhibited the higher photocatalytic activity, which degradation efficiency reaches 99.5% under UV irradiation for 30min. The big specific surface area of ZnS nanostructures are believed to greatly affect the final degradation efficiency of MO in our research. Moreover, the mechanism of enhanced photocatalytic activity was also investigated and the O2− plays a dominant role during degradation process.

Hydroxide SrSn(OH)6: A new photocatalyst for degradation of benzene and rhodamine B

A novel photocatalyst SrSn(OH)6 was successfully synthesized via a facile homogeneous precipitation method. The photocatalytic activities of the as-prepared SrSn(OH)6 were evaluated by the degradation of benzene and rhodamine B under the irradiation of 254nm UV light. The experimental results indicated that SrSn(OH)6 synthesized at a lower pH value had a better photocatalytic activity. Furthermore, compared with commercial TiO2 (P25), the as-prepared SrSn(OH)6 showed a better photocatalytic performance for degradation of benzene under 254nm UV irradiation. During 32h of photocatalytic process, the conversion ratio of benzene over SrSn(OH)6 and TiO2 (P25) were 31% and 11%, and the mineralization ratio were about 55% and 16%, respectively. Based on the characterization results and the detection of active species, the high photocatalytic activity of SrSn(OH)6 may attribute to the OH radicals, which play an important role in the degradation of both benzene and rhodamine B. This article enriches the study of hydroxide stannates and has reference significance for other hydroxide stannates. This work shows that the hexagonal phase of hydroxide stannate may not have much better or worse photocatalytic performance than cubic phase does. So, the crystal phase cannot be the main reason to influence the photocatalytic performance of hydroxide stannates. More research of other hydroxide stannates should focus on making good use of the hydroxyl groups in its structure.