Bond-Energy-Driven, Low- or High-Angle-Grain-Boundary-Movement-Mediated Synthesis of Porous Se-Te for Use in Water-Splitting Reactions.

Herein, for the first time, we applied the metal-metal-bond-energy factor to the evolution of a porous Se-Te alloy. The porous Se-Te material has been prepared from the constituents' elemental states, through only a heating-cooling process in silicone oil without the use of any reagent, surfactant, or capping agent. Surprisingly, the reaction occurred at a much lower temperature (240 °C) than the mp (450 °C) of Te0. The reaction's nucleation and growth by means of varied bond energy have been clarified for the first time. A difference in the bond energies of a hetero metal-metal bond (Se-Te) and a homo metal-metal bond (Se-Se) directs nucleation and growth toward the fabrication of a porous structure, even from the constituents' elemental states, in which low-angle-grain-boundary (LAGB) and high-angle-grain-boundary (HAGB) movements play governing roles. Proper band-gap alignment of Se and Te makes the alloy composite applicable to water-splitting reactions under Xe-arc-lamp illumination. PEC efficiency of Se-Te was found to be higher than those reported for Se and other composite materials.

Suitable Morphology Makes CoSn(OH)6 Nanostructure a Superior Electrochemical Pseudocapacitor.

Morphology of a material with different facet, edge, kink, etc., generally influences the rate of a catalytic reaction.1,2 Herein, we account for the importance of altered morphology of a nanomaterial for a supercapacitor device and employed CoSn(OH)6 as an electrode material. Suitable fabrication of a stable aqueous asymmetric supercapacitor (AAS) using metal hydroxide as positive electrode can be beneficial if the high energy density is derived without sacrificing the power density. Here we have synthesized an uncommon hierarchical mesoporous nanostructured (HNS) CoSn(OH)6 to fabricate a pseudocapacitor. In this endeavor, NH3 is found to be a well-suited hydrolyzing agent for the synthesis.3 Serendipitously, HNS was transformed into favored cubic nanostructure (CNS) in NaOH solution. In solution, NaOH acts as a structure directing as well as an etching agent. Both the samples (HNS & CNS) were used as pseudocapacitor electrodes in KOH electrolyte independently, which is reported for the first time. The HNS exhibits very high specific capacitance value (2545 F/g at 2.5 A/g specific current) with better cyclic durability over CNS sample (851 F/g at 2.5 A/g specific current). To examine the real cell application, we used HNS sample as the positive electrode material with the activated carbon (AC) as the negative electrode material for the development of an aqueous asymmetric supercapacitor (AAS). The as-fabricated AAS exhibited very high specific capacitance value of 713 F/g at a specific current of 1.5 A/g and retained 92% specific capacitance value even after 10 000 charge-discharge cycles. A maximum energy density of 63.5 Wh kg(-1) and a maximum power density of 5277 W kg(-1) were ascertained from the as-fabricated AAS, HNS CoSn(OH)6//AC.

A ternary Cu2O-Cu-CuO nanocomposite: a catalyst with intriguing activity.

In this work, the syntheses of Cu2O as well as Cu(0) nanoparticle catalysts are presented. Copper acetate monohydrate produced two distinctly different catalyst particles with varying concentrations of hydrazine hydrate at room temperature without using any surfactant or support. Then both of them were employed separately for 4-nitrophenol reduction in aqueous solution in the presence of sodium borohydride at room temperature. To our surprise, it was noticed that the catalytic activity of Cu2O was much higher than that of the metal Cu(0) nanoparticles. We have confirmed the reason for the exceptionally high catalytic activity of cuprous oxide nanoparticles over other noble metal nanoparticles for 4-nitrophenol reduction. A plausible mechanism has been reported. The unusual activity of Cu2O nanoparticles in the reduction reaction has been observed because of the in situ generated ternary nanocomposite, Cu2O-Cu-CuO, which rapidly relays electrons and acts as a better catalyst. In this ternary composite, highly active in situ generated Cu(0) is proved to be responsible for the hydride transfer reaction. The mechanism of 4-nitrophenol reduction has been established from supporting TEM studies. To further support our proposition, we have prepared a compositionally similar Cu2O-Cu-CuO nanocomposite using Cu2O and sodium borohydride which however displayed lower rate of reduction than that of the in situ produced ternary nanocomposite. The evolution of isolated Cu(0) nanoparticles for 4-nitrophenol reduction from Cu2O under surfactant-free condition has also been taken into consideration. The synthetic procedures of cuprous oxide as well as its catalytic activity in the reduction of 4-nitrophenol are very convenient, fast, cost-effective, and easily operable in aqueous medium and were followed spectrophotometrically. Additionally, the Cu2O-catalyzed 4-nitrophenol reduction methodology was extended further to the reduction of electronically diverse nitroarenes. This concise catalytic process in aqueous medium at room temperature revealed an unprecedented catalytic performance which would draw attention across the whole research community.

Evolution of amorphous selenium nanoballs in silicone oil and their solvent induced morphological transformation.

Selenium generally exhibits preferential habitual 1D growth as a result of redox reactions of selenium compounds. Commercial Se powder melts in silicone oil under refluxing conditions and upon subsequent cooling evolve amorphous Se nanoballs (SNBs). Further ultrapure crystalline 1D Se grows from SNBs due to solvent mediated oriented attachment.

Fabrication of superhydrophobic copper surface on various substrates for roll-off, self-cleaning, and water/oil separation.

Superhydrophobic surfaces prevent percolation of water droplets and thus render roll-off, self-cleaning, corrosion protection, etc., which find day-to-day and industrial applications. In this work, we developed a facile, cost-effective, and free-standing method for direct fabrication of copper nanoparticles to engender superhydrophobicity for various flat and irregular surfaces such as glass, transparency sheet (plastic), cotton wool, textile, and silicon substrates. The fabrication of as-prepared superhydrophobic surfaces was accomplished using a simple chemical reduction of copper acetate by hydrazine hydrate at room temperature. The surface morphological studies demonstrate that the as-prepared surfaces are rough and display superhydrophobic character on wetting due to generation of air pockets (The Cassie-Baxter state). Because of the low adhesion of water droplets on the as-prepared surfaces, the surfaces exhibited not only high water contact angle (164 ± 2°, 5 µL droplets) but also superb roll-off and self-cleaning properties. Superhydrophobic copper nanoparticle coated glass surface uniquely withstands water (10 min), mild alkali (5 min in saturated aqueous NaHCO3 of pH ≈ 9), acids (10 s in dilute HNO3, H2SO4 of pH ≈ 5) and thiol (10 s in neat 1-octanethiol) at room temperature (25-35 °C). Again as-prepared surface (cotton wool) was also found to be very effective for water-kerosene separation due to its superhydrophobic and oleophilic character. Additionally, the superhydrophobic copper nanoparticle (deposited on glass surface) was found to exhibit antibacterial activity against both Gram-negative and Gram-positive bacteria.

Ligand chain length conveys thermochromism.

Thermochromic properties of a series of non-ionic copper compounds have been reported. Herein, we demonstrate that Cu(II) ion with straight-chain primary amine (A) and alpha-linolenic (fatty acid, AL) co-jointly exhibit thermochromic properties. In the current case, we determined that thermochromism becomes ligand chain length-dependent and at least one of the ligands (A or AL) must be long chain. Thermochromism is attributed to a balanced competition between the fatty acids and amines for the copper(II) centre. The structure-property relationship of the non-ionic copper compounds Cu(AL)2(A)2 has been substantiated by various physical measurements along with detailed theoretical studies based on time-dependent density functional theory. It is presumed from our results that the compound would be a useful material for temperature-sensor applications.

Account of nitroarene reduction with size- and facet-controlled CuO-MnO2 nanocomposites.

In this work, we propose a systematic and delicate size- and shape-controlled synthesis of CuO-MnO2 composite nanostructures from time-dependent redox transformation reactions between Cu2O and KMnO4. The parental size and shape of Cu2O nanostructures are retained, even after the redox transformation, but the morphology becomes porous in nature. After prolonged reaction times (>24 h), the product shapes are ruptured, and as a result, tiny spherical porous nanocomposites of ∼100 nm in size are obtained. This method is highly advantageous due to its low cost, its easy operation, and a surfactant or stabilizing agent-free approach with high reproducibility, and it provides a facile but new way to fabricate porous CuO-MnO2 nanocomposites of varied shape and size. The composite nanomaterials act as efficient recyclable catalysts for nitroarene reduction in water at room temperature. The time-dependent reduction kinetics can be easily monitored by using UV-vis spectrophotometer. The catalytic system is found to be very useful toward the reduction of nitro compounds, regardless of the type and position of the substituent(s). Furthermore, it is revealed that CuO-MnO2 composite nanomaterials exhibit facet-dependent catalytic activity toward nitroarene reduction, where the (111) facet of the composite stands to be more active than that of the (100) facet. The results are also corroborated from the BET surface area measurements. It is worthwhile to mention that porous tiny spheres (product of 48 h reaction) exhibit the highest catalytic activity due to pronounced surface area and smaller size.

An efficient strategy for the general synthesis of 3-aryl substituted pyrazolo[5,1-c][1,4]benzoxazines and pyrazolo[1,5-a][1,4]benzodiazepin-6(4H)-ones.

An efficient strategy for the general synthesis of 3-aryl substituted pyrazolo[5,1-c][1,4]benzoxazines and pyrazolo[1,5-a][1,4]benzodiazepin-6(4H)-ones has been developed using intramolecular 1,3-dipolar cycloaddition. The hydrazonoyl chloride, the precursor of the cycloadduct, is accessed easily through a two-step reaction carried out in one-pot. It is then used without purification for the base induced formation of the nitrilimine, which undergoes subsequent in situ intramolecular cycloaddition with an alkyne to afford the desired product. The reaction protocol has also been applied in bis-heteroannulation and in the synthesis of uracil derivatives of biological interest. The operational simplicity of the process, the use of cheap starting materials, and the relatively short reaction times required make the process convenient and practical.

An expedient and facile route for the general synthesis of 3-aryl substituted 1,2,3-triazolo[1,5-a][1,4]benzodiazepin-6-ones and 1,2,3-triazolo[1,5-a][1,5]benzodiazocin-7-ones.

We describe herein a convenient approach for the general synthesis of novel tricyclic scaffolds incorporating a fusion of the 1,2,3-triazole ring with difficultly obtainable medium sized rings such as [1,4]benzodiazepin-5-ones and [1,5]benzodiazocin-6-ones through Sonogashira coupling of an aryl iodide with 2-amino-N-methyl-N-(prop-2-ynyl)benzamide or homologue followed by in situ diazotisation, azidation and cycloaddition reactions. The strategy also allows easy accessibility of the corresponding amide-reduced analogues. The operational simplicity and easy substrate availability make the process cost effective and practical.