Ethanol templated synthesis of microporous/mesoporous nanozinc oxide with multi-level structure and its outstanding photo-catalytic properties.

Zinc oxide has been of interest because of its efficient redox capacity in the UV spectral region. However, the high bandwidth limits its application in the visible region. Although synthesizing heterojunctions and doping with other elements have become the focus of the problem, it inevitably has an impact on the environment. In contrast, the template method is not only environmentally friendly but also can be used to increase the degradation rate by changing the nanoparticle mesoporous structure. Microporous/mesoporous zinc oxide with multi-level structure was synthesized using anhydrous ethanol as a green templating agent in a mild and energy-efficient method. The prepared nZnO was characterized using XRD, SEM, BET, and HR-TEM. XRD confirmed that the formation of hexagonal wurtzite zincite nZnO with good crystallinity. SEM results showed that the products were flower-like structures composed of nanosheets with a thickness of 20 nm and an average diameter of 400 nm. TEM and BET confirmed the presence of pits with diameters ranging from about 1 nm to 20 nm existed on the surface of the nanosheets, while the specific surface area of 28.05 m2/g and the pore volume of 0.069 cm3/g also provide advantages for nZnO as a photocatalytic material. The synthesized nZnO overcame the disadvantage of responding only in the UV region, and the photocatalytic degradation efficiency of MB reached 93.2% after 60 min of xenon lamp irradiation, and stabilized at 86.15% after five photocycling tests. Compared with other kinds of templates, anhydrous ethanol has the advantages of environmental friendliness and simple post-processing, and it also provides ideas for the synthesis of multilevel structures of other nanomaterials.

Over 11 kg m-2 h-1 Evaporation Rate Achieved by Cooling Metal-Organic Framework Foam with Pine Needle-Like Hierarchical Structures to Subambient Temperature.

Solar steam generation has become a hot research topic because of its great potential to alleviate the drinking water crisis without extra energy input. Although some efforts focusing on designing spatial geometry have been made to multiply the evaporation performances of up-to-date three-dimensional evaporators, they still have some shortcomings, such as low material and space utilization efficiencies, complex spatial geometry, energy loss due to the hot solar absorption surface, and salt crystallization due to inefficient water supply. Herein, a biomimetic copper-based metal-organic framework (Cu-Cu(OH)2-MOF) foam sheet with interconnected pores and pine needle-like hierarchical structures consisting of Cu(OH)2 nanowires and MOF nanowhiskers is fabricated. The pine needle-like hierarchical structures of Cu-Cu(OH)2-MOF foam contribute to absorbing solar energy and supplying sufficient water by trapping incident light and enhancing the capillary force, respectively. Inspired by drying clothes outside under solar irradiation, through exposing one end of the Cu-Cu(OH)2-MOF foam to air, the biface evaporator achieves a subambient evaporation surface temperature and an evaporation rate of up to 3.27 kg m-2 h-1 under only one sun illumination. Furthermore, when coupled with an air flow, the biface evaporator realizes an excellent evaporation rate of 11.58 kg m-2 h-1 with an energy efficiency of 160.07% even in seawater, ensuring its great application prospect to be used in drinking water production and seawater desalination.

Low-Temperature Synthesis of Monolithic Titanium Carbide/Carbon Composite Aerogel.

Resorcinol-formaldehyde/titanium dioxide composite (RF/TiO2) gel was prepared simultaneously by acid catalysis and then dried to aerogel with supercritical fluid CO2. The carbon/titanium dioxide aerogel was obtained by carbonization and then converted to nanoporous titanium carbide/carbon composite aerogel via 800 °C magnesiothermic catalysis. Meanwhile, the evolution of the samples in different stages was characterized by X-ray diffraction (XRD), an energy-dispersive X-ray (EDX) spectrometer, a scanning electron microscope (SEM), a transmission electron microscope (TEM) and specific surface area analysis (BET). The results showed that the final product was nanoporous TiC/C composite aerogel with a low apparent density of 339.5 mg/cm3 and a high specific surface area of 459.5 m2/g. Comparing to C aerogel, it could also be considered as one type of highly potential material with efficient photothermal conversion. The idea of converting oxide-carbon composite into titanium carbide via the confining template and low-temperature magnesiothermic catalysis may provide new sight to the synthesis of novel nanoscale carbide materials.

Receptor-like kinase OsCR4 controls leaf morphogenesis and embryogenesis by fixing the distribution of auxin in rice.

Cell differentiation is a key event in organ development; it involves auxin gradient formation, cell signaling, and transcriptional regulation. Yet, how these processes are orchestrated during leaf morphogenesis is poorly understood. Here, we demonstrate an essential role for the receptor-like kinase OsCR4 in leaf development. oscr4 loss-of-function mutants displayed short shoots and roots, with tiny, crinkly, or even dead leaves. The delayed outgrowth of the first three leaves and seminal root in oscr4 was due to defects in plumule and radicle formation during embryogenesis. The deformed epidermal, mesophyll, and vascular tissues observed in oscr4 leaves arose at the postembryo stage; the corresponding expression pattern of proOsCR4:GUS in embryos and young leaves suggests that OsCR4 functions in these tissues. Signals from the auxin reporter DR5rev:VENUS were found to be altered in oscr4 embryos and disorganized in oscr4 leaves, in which indole-3-acetic acid accumulation was further revealed by immunofluorescence. OsWOX3A, which is auxin responsive and related to leaf development, was activated extensively and ectopically in oscr4 leaves, partially accounting for the observed lack of cell differentiation. Our data suggest that OsCR4 plays a fundamental role in leaf morphogenesis and embryogenesis by fixing the distribution of auxin.

Enhanced Photothermal Conversion by Hot-Electron Effect in Ultrablack Carbon Aerogel for Solar Steam Generation.

Ecofriendly, highly effective, and low-cost solar steam generation has great potential in the applications of power generation, seawater desalination, and industry wastewater treatment. Solar steam generation requires an evaporator that has strong light absorption over a wide-frequency band (200-3000 nm), high photothermal conversion efficiency, and good thermal insulation to avoid excessive heat loss. Herein, foam-strengthened ultrablack carbon aerogels (CAs) with micropores, mesopores, and macropores were prepared using freeze drying. The small-size conductor effect in ultrablack CAs could increase the surface electron concentration, leading to the increase of light absorption and ultimately enhancing photothermal conversion efficiency. Consequently, under 1 sun illumination, dried CA-5 exhibited a fast temperature rise rate and the highest thermal equilibrium temperature of 87.6 °C among CAs, the equilibrium temperature is 20.8 °C higher than that of the foam. Besides, CA-5 exhibited a high water evaporation rate of 1.29 kg m-2 h-1 under only 1 sun illumination. To further increase the hot-electron effect, CO2 activation was implemented. The highest water evaporation rate among activated CAs (ACAs) was 1.37 kg m-2 h-1, which is about 2.85 times higher than that of pure water. The highest water evaporation efficiency was 87.51%, which is better than most of the previously reported evaporation efficiencies. Besides the hot-electron enhancement effect, ACAs with thermal insulation, mechanical strength, and thermal stability show great potential for producing fresh water from seawater, industrial wastewater, and even concentrated acidic or alkaline solutions.

Synthesis and characterization of a ZnGa2O4:Cr3+-based aerogel.

A ZnGa2O4:Cr3+-based aerogel was prepared by using polyacrylic acid (PAA) as a dispersant and propylene oxide (PO) as a crosslinking agent via CO2 supercritical drying. The results of BET and SEM show that there is a certain degree of macroporosity (d > 50 nm) in the aerogel. It has a dendritic structure and the interior is relatively loose. EDS mapping illustrates that the elements Zn, Ga, and Cr are evenly distributed in the aerogel. In addition, the diffuse reflectance spectra and the emission spectrum of samples with different calcination temperatures were also characterized. Both demonstrated, when the calcination temperature is greater than 600 °C, that the sample crystallizes and has a significant emission, which is consistent with the XRD and TG-DSG results. Finally, the ZnGa2O4:Cr3+-based aerogel also exhibits excellent long afterglow performance and high photocatalytic performance with 80.1% methylene blue (MB) degradation at 20 min.

One-Dimension Diffusion Preparation of Concentration-Gradient Fe2O3/SiO2 Aerogel.

Concentration-gradient Fe2O3/SiO2 aerogels were prepared by placing an MTMS (methyltrimethoxysilane)-derived SiO2 aerogel on an iron gauze with an HCl atmosphere via one-dimensional diffusion, ammonia-atmosphere fixing, supercritical fluid drying and thermal treatment. The energy dispersive spectra show that the Fe/Si molar ratios change gradually from 2.14% to 18.48% with a height of 40 mm. Pore-size distribution results show that the average pore size of the sample decreases from 15.8 nm to 3.1 nm after diffusion. This corresponds well with TEM results, indicating a pore-filling effect of the Fe compound. In order to precisely control the gradient, diffusion kinetics are further studied by analyzing the influence of time and position on the concentration of the wet gel. At last, it is found that the diffusion process could be fitted well with the one-dimensional model of Fick's second law, demonstrating the feasibility of the precise design and control of the concentration gradient.

A facile strategy for the synthesis of graphene/V2O5 nanospheres and graphene/VN nanospheres derived from a single graphene oxide-wrapped VO x nanosphere precursor for hybrid supercapacitors.

It remains a challenge to develop a facile approach to prepare positive and negative electrode materials with good electrochemical performance for application in hybrid supercapacitors. In this study, based on a facile strategy, a single graphene oxide-wrapped VO x nanosphere precursor is transformed into both electrodes through different thermal treatments (i.e., graphene/VN nanospheres negative electrode materials and graphene/V2O5 nanospheres positive electrode materials) for hybrid supercapacitors. The conformally wrapped graphene has a significant influence on the electrochemical performance of VN and V2O5, deriving from the simultaneous improvements in electronic conductivity, structural stability, and electrolyte transport. Benefitting from these merits, the as-prepared graphene/VN nanospheres and graphene/V2O5 nanospheres exhibit excellent electrochemical performance for HSCs with high specific capacitance (83 F g-1) and good long cycle life (90% specific capacitance retained after 7000 cycles). Furthermore, graphene/VN nanospheres//graphene/V2O5 nanosphere HSCs can deliver a high energy density of 35.2 W h kg-1 at 0.4 kW kg-1 and maintain about 70% high energy density even at a high power density of 8 kW kg-1. Such impressive results of the hybrid supercapacitors show great potential in vanadium-based electrode materials for promising applications in high performance energy storage systems.

Rheological behaviors of cellulose in 1-ethyl-3-methylimidazolium chloride/dimethylsulfoxide.

Dynamic rheological behaviors of α-cellulose 1-ethyl-3-methylimidazolium chloride ([Emim]Cl)/dimethylsulfoxide (DMSO) solutions were investigated in a large range of cellulose concentrations (0.1-10 wt%) at 25°C. The overlap concentration c* and the entanglement concentration ce for cellulose in [Emim]Cl/DMSO were determined to be 0.5 wt% and 2.0 wt% respectively, and the exponents of the specific viscosity ηsp versus cellulose concentration c were determined as 1.1, 2.1 and 4.7 for dilute, semidilute unentangled and entangled regimes respectively, which were in accordance with the scaling prediction for neutral polymer in θ solvent. Under the same cellulose concentration, the complex viscosity η*, the reptation time τrep and the relaxation time of a segment between entanglements τe all decreased with increasing DMSO content in the solvent, while the number of entanglements of cellulose chains and the molar mass of an entanglement strand Me both remained unchanged.

Flow behavior and linear viscoelasticity of cellulose 1-allyl-3-methylimidazolium formate solutions.

The rheological properties of α-cellulose 1-allyl-3-methylimidazolium formate solutions were investigated using shear viscosity and dynamic rheological measurements in a large range of concentrations (0.1-10 wt%) at 25 °C. In steady shear measurement, the overlap concentration (c*) and the entanglement concentration (c(e)) were determined to be 0.5 and 2.0 wt% respectively, and the exponents of the specific viscosity (η(sp)) versus the concentration (c) were determined as 1.0, 2.0 and 4.7 for dilute, semidilute unentangled and entangled regimes respectively, which were in accordance with the scaling prediction for neutral polymer in θ solvent. The slopes of the relaxation time (τ) against the concentration for semidilute unentangled and entangled regimes were observed as 1.0 and 2.5 respectively. In dilute and semidilute unentangled regimes, failure of the Cox-Merz rule with steady shear viscosity larger than complex viscosity was observed; while the deviation from the Cox-Merz rule disappeared in semidilute entangled regime.

1-Benzyl-3-methyl-imidazolium chloride 0.25-hydrate.

The asymmetric unit of the title compound, C(11)H(13)N(2) (+)·Cl(-), contains two independent ion pairs and and half a solvent water mol-ecule (m site symmetry for the O atom). The imidazole ring is oriented at dihedral angles of 66.61 (3) and 89.17 (3)° with respect to the aromatic ring in the two cations. In the crystal, O-H⋯(O,Cl) hydrogen bonds and π-π stacking inter-actions between the imidazole ring of one mol-ecule and the aromatic ring of another [perpendicular distance = 3.4 (4) Å] link the mol-ecules.

2-Nitro-p-phenyl-ene bis-(toluene-sulfonate).

In the mol-ecule of the title compound, C(20)H(17)NO(8)S(2), the two toluene rings are oriented at a dihedral angle of 3.65 (4)°, while the nitrophenyl ring is oriented at dihedral angles of 44.39 (3) and 47.44 (3)° with respect to the toluene rings. An intra-molecular C-H⋯O hydrogen bond results in the formation of a five-membered ring, which adopts an envelope conformation. In the crystal structure, inter-molecular C-H⋯O hydrogen bonds link the mol-ecules. There is a π-π contact between the toluene rings [centroid-centroid distance = 4.035 (1) Å].

3-Hydr-oxy-4-nitro-phenyl acetate.

In the mol-ecule of the title compound, C(8)H(7)NO(5), the acetate group is oriented with respect to the aromatic ring at a dihedral angle of 85.30 (3)°. An intra-molecular O-H⋯O hydrogen bond results in the formation of a non-planar six-membered ring, adopting an envelope conformation. In the crystal structure, inter-molecular C-H⋯O hydrogen bonds link the mol-ecules.