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•Commercially available Prussian blue (PB) removes ppb-level Cs+ in water.•Cs+ rapidly absorbs in PB by concerted two adsorption mechanism.•The prominent ability of PB eliminate Cs+ ...exerts in also an artificial seawater.
Many kinds of laboratory-scale synthesized Prussian blue-based materials (PBs) have been investigated as removal agents of radioactive Cs+via the adsorption of Cs+ in the crystal lattice of PBs. The removal ability is canonically demonstrated at high Cs+ concentrations, such as ppm order. However, the actual efflux of radioactive Cs+ after nuclear accidents in the environment is ppb level by dilution. We investigate the Cs+ removal ability of commercially available PB-based compounds at low Cs+ concentration below ppm order. Cs+ cations are rapidly removed using the PBs in a few minutes in water below 500 ppb Cs+ concentrations. Na+ cations in the crystal lattices of a used PB are released to water during the removal process. However, the released amount of Na+ is low compared with the adsorbed amount of Cs+, which indicates that Cs+ cations are removed by concerted two adsorption mechanisms: one is simple adsorption to the vacancy pores, and the other is ion-exchange between Cs+ and Na+. The rapid Cs+ removal is also observed on PBs in artificial seawater, whereas the Cs+ removal ability of zeolites as different types of Cs+ adsorbents disappears under the same removal condition.
•CuO/ZnO composite nanoarrays on brass (Cu–Zn alloy) plate were successfully obtained by a facile one-step and low-temperature (80°C) alkaline vapor oxidation process.•It was revealed that the ...nanoarrays consist of CuO nanoflowers or nanobelts (top)/ZnO nanorods (bottom) bilayer structure by XRD, SEM, SEM-EDX, and GD-OES investigations.•The CuO/ZnO/brass nanocomposite electrode was electrocatalytically active toward glucose oxidation.•The CuO nanoflowers/ZnO nanorods/brass plate nonenzymatic glucose sensor presents attractive analytical features such as a fast response time, high sensitivity, and low detection limit.
CuO/ZnO nanocomposite materials have attracted widespread attention because of their scientific and technological importance as, for example, photocatalysts, gas and humidity sensors, catalysts for H2 production and organic synthesis, and solar cells. High-temperature and/or complicated multistep processes are usually used to prepare these composites. Here we demonstrate a low-temperature and facile one-step synthesis of CuO nanoflowers/ZnO nanorods composite arrays via an alkaline vapor oxidation process. The CuO/ZnO composite nanoarrays show high electrocatalytic activity toward glucose oxidation.
Dissipative structures are macroscopic or even larger ordered structures that emerge under conditions far from thermodynamic equilibrium. In contrast, molecular self-assembly has been investigated ...near at the thermodynamic equilibrium, which provides basically smaller, nano-to-micron sized structures. In terms of the formation principles, there exists an essential gap between the dissipative structures and molecular self-assemblies. To fill this gap, molecular self-assembly of light-reducible organic–inorganic ion pairs was investigated under far-from-equilibrium conditions. When solid films of tetraalkylammonium hexafluorophosphate were immersed in aqueous Au(OH)4 – and immediately photoirradiated, gold nanowires are formed at the solid–aqueous interface. On the other hand, such nanowires were not formed when the photoirradiation was conducted for the specimens after a prolonged immersion period of 60 min. These observations indicate spontaneous growth of dissipative nanofibrous self-assemblies consisting of light-reducible ion pairs tetraalkylammonium ionAu(OH)4 – at the interface and their photoreduction to give developed nanowires. These nanowires are not available by the photoreduction of Au(OH)4 – ions under conditions near at the thermodynamic equilibrium. A picture for the dissipative nanostructures is obtained: the formation of amphiphilic light-reducible nanowire structures is based on the static self-assembly near at the thermodynamic equilibrium, whereas their spontaneous, anisotropic growth from the interface to the aqueous phase is directed by dynamic, dissipative self-assembly phenomena under the far-from-equilibrium conditions. Thus, the both elements of dissipative self-assembly (dynamic) and static molecular self-assembly fuse together at the nanoscale, which is an essential feature of the dissipative nanostructures.
Ag clusters (mean diameter = 1.5 nm, standard deviation = 0.37 nm) were photodeposited on TiO2 particles in a highly dispersed state. The loading of a small amount of the Ag clusters (0.24 wt %) ...dramatically enhanced both the activity for the TiO2 photocatalytic reduction of nitrobenzene and the product selectivity of aniline. The essential action mechanism of the Ag clusters is discussed.
Anatase–brookite composite nanocrystals have successfully been synthesized at 50 °C using a simple liquid-phase process. The photocatalytic activity of the sample for the gas-phase oxidation of CH
...3CHO is 5.4 times greater than that of a single-phase anatase sample with comparable crystallite size and surface area. Electron energy loss spectra suggest that this high activity results from junction between anatase and brookite crystals.
Photocatalytic activity under visible light irradiation was generated by doping a small amount of Co2+ ions into TiO2 particles. Nanometer-sized particles with the composition xCoO–(100−x) TiO2 ...(xCo/TiO2; 0≤x≤6.0) were prepared from TiOSO4·4.5H2O and Co(CH3COO)2·4H2O in an ethanol–water solution containing NaOH under reflux. The photoreactivity of xCo/TiO2 was evaluated by the rate of CH3CHO degradation. The Co2+ ion doping (0.01≤x≤0.27) not only enhanced the photocatalytic activity under ultraviolet-visible (λ>300 nm) light irradiation but also induced the visible light (λ>400 nm) response. The highest photocatalytic activities were obtained at x=0.03 for both irradiations.
Rutile TiO(2) particles were partly dissolved into aqueous solutions of H(2)SO(4), and the Ti(4+) ions were reprecipitated by adding NH(3) aq. Rutile-anatase coupled TiO(2) particles were prepared by ...heating the solid recovered after centrifugation of the suspension. The content of anatase (c(A), wt%) could be controlled arbitrarily by changing the dissolved amount of rutile. The photocatalytic activity for the gas-phase oxidation of acetaldehyde was evaluated. The first-order rate constant, k, strongly depended on both c(A) and heating temperature (T(c)), increasing with an increase in T(c) at T(c)</=800 degrees C. The sample with c(A)=0.5 wt% prepared at T(c)=800 degrees C exhibited a much higher level of activity (k=0.94 h(-1)m(-2)) than those of pure rutile (k=0.08 h(-1)m(-2)) and anatase (k=0.34 h(-1)m(-2)). This remarkable enhancing effect was explained mainly in terms of photoinduced interfacial electron transfer from anatase to rutile.
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