Small Amount Of NaOH Research Articles

One‐step synthesis of flower‐like η‐Al 2 O 3 via supercritical hydrothermal method

In this Letter, flower-like η-Al2O3 nanostructure was synthesised via hydrothermal method without any surfactant or further calcination. A molten salt bath rose the reactor temperature as much as 500°C to achieve the supercritical condition. Such a high temperature caused a rapid one-step synthesis in two minutes. Al(NO3)3 and NaOH were the only precursors. Synthesised powders were investigated by X-ray powder diffraction and scanning electron microscope, and the specific surface area was also determined by N2 adsorption–desorption analysis. Increasing reaction time >2 min caused undesired Ostwald ripening. So instead of giving more time, a small amount of NaOH was added to form the η-Al2O3 phase. Moreover, the morphology of η-Al2O3 changed to flower-like by increasing the density of the supercritical fluid. Finally, the probable mechanism of flower-like morphology formation was proposed in two steps.

Sodium Hydroxide Assisted Work Function Tuning of Hole Transport Material for Efficient Wide-Bandgap Perovskite Solar Cells

Poly(3,4-ethylenedioxythiophene) polystyrene sulfonate (PEDOT:PSS) is widely used as hole transport material (HTM) in perovskite solar cells (PSC) of inverted structure. However, suitable energy level alignment between the Perovskite material and PEDOT.PSS is very important for proper charge transportation. Perovskite materials at various compositions of organic-inorganic compounds usually have different energy levels. Therefore, it is essential to tune the energy level hence the work function of PEDOT:PSS material to fulfill the requirement. In this work, 0.1 M sodium hydroxide (NaOH) is employed to modify the work function (Φ) of PEDOT:PSS HTM in MA0.9Cs0.1Pb(I0.6Br0.4)3 based wide-bandgap (1.82 eV) perovskite solar cells. Kelvin probe force microscopy (KPFM) confirms that Φ of the HTM gradually increases with the addition of very small amount of NaOH. An increase of Φ indicates that highest occupied molecular orbital (HOMO) level of HTM is getting closer to the HOMO of perovskite material which is beneficial for photogenerated hole extraction. Quenching of perovskite emission spectra in steady state photoluminescence (PL) spectroscopy also supports this enhanced hole extraction. Essentially, the optimum amount of NaOH needs to be added as higher amount can adversely affect the electrical conductivity of PEDOT:PSS. Besides, added NaOH provides Na+ ions in PEDOT:PSS which transforms some acidic PSS-H into neutral PSS-Na causing retardation of counter-ion exchange at perovskite and HTM interface. This helps to reduce the potential energy loss in the interface. Consequently, the final power conversion efficiency of the PSC is increased from 10.92% to 12.97% through the improvement of all performance related parameters such as short circuit current density (Jsc ), open circuit voltage (Voc) and fill factor (FF). In addition, similar characteristics X-ray diffraction (XRD) peaks reveal that NaOH treatment in HTM does not affect the regular crystallization of MA0.9Cs0.1Pb(I0.6Br0.4)3 perovskite.

Mild hydrothermal synthesis of BiFeO3 films on BiFeO3 seed-layer-coated indium tin oxide substrates and their piezo-related applications

This paper reports the development of a facile hydrothermal approach to grow pure BiFeO3 (BFO) films on BFO seed-layer-coated indium tin oxide/glass substrates in mild conditions. The results indicate that the seed layer and no involvement of complex agents were crucial for the mild condition [small amount of NaOH (approximately 1 g); 180 °C] because of homogeneous nucleation and growth of the BFO films. The phase and crystallinity of the BFO films were studied through X-ray diffraction, high-resolution transmission electron microscopy, and selected area electron diffraction. The stoichiometric BFO films were ascertained using electron-probe energy-dispersive spectroscopy. The band gap of the BFO films was approximately 2.6 eV. The induced piezopotential of approximately 2.0 mV at a stress of approximately 0.6 GPa indicated the piezoelectric property of the obtained BFO films. The associated piezotronic properties were determined from the asymmetric current–voltage characteristics. The piezophotocatalytic efficiency for methylene blue degradation under visible light irradiation was approximately three times higher than for photocatalysis without stress.

Hydrothermal improvement for 3R-CuFeO2 delafossite growth by control of mineralizer and reaction atmosphere

Delafossite CuFeO2 oxides were grown inside a hydrothermal reactor using Cu2O and FeOOH as precursors and NaOH as mineralizer. During this work the effect of the NaOH mineralizer and the reaction atmosphere was studied by varying the amount of NaOH used in the hydrothermal synthesis and by changing the reactor atmosphere from room air to high purity nitrogen. The oxides obtained were analyzed with Raman Spectroscopy, Fourier Transform Infrared Spectroscopy (FT-IR), X-ray diffraction (XRD), X-ray Photoelectron spectroscopy (XPS), Field Emission Scanning Electron Microscopy (FESEM) and Energy Dispersive X-ray Spectroscopy (EDS), in order to obtain their morphological, chemical and structural characteristics. It was found that increasing the amount of mineralizer from 0.4 g up to 1.02 g improves considerably the hydrothermal reaction efficiency obtaining a resulting oxide with 93% of 3R-CuFeO2 phase and a subsequent decrease of the 2H-CuFeO2 phase. Moreover, using the same hydrothermal route it was shown possible to obtain high purity CuFeO2 compounds using small amounts of NaOH (0.4 g) if the reaction is performed under a non-oxidative atmosphere injecting pure nitrogen gas to the hydrothermal reactor where an increase of 3R-CuFeO2 phase from 36% to 94% was obtained. Finally, direct band gap of the semiconducting oxides were estimated using Tauc method from UV–vis spectra obtained by Diffuse Reflectance spectroscopy.

Facile synthesis of hierarchical porous carbon for supercapacitor with enhanced electrochemical performance

Herein, we use a facile one-pot strategy to synthesis hierarchical porous carbon from sodium alginate (SA). After pre-conditioned at 200°C, SA was activated by a small amount of NaOH at 800°C. In the sintering process, the SA can achieve a self-activation effect which can effectively reduce the dosage of alkaline activator (in a weight ratio of 5:4) during activating process. Finally, the end product exhibits a capacity of 451F/g in 2M KOH aqueous solution and exhibit excellent rate ability. The cycle ability of OSADC-5 was tested at 10A/g, and after 10,000 cycles the capacitance retention is 99% which shows superb electrochemistry stability.

Formation mechanism of apex-truncated octahedral Cu2O microcrystal

Corner-truncated octahedral Cu2O microcrystal was synthesized by a typical solution phase reduction method with CuSO4, glucose, and a small amount of NaOH. Researching into the reaction process, we found that the Cu2O microcrystal grew following the sol–gel growth model, instead of Lamer nucleation–diffusion model. The roles that OH− and SO42− played in the formation of the octahedral morphology were revealed by separating them and investigating the corresponding products, respectively. We used PVP (polyvinylpyrrolidone) in another experiment to show that the influence of the organic surfactant on the crystal habit may also be demonstrated more clearly using this method.

Biodiesel derived glycerol hydrogenolysis to 1,2-propanediol on Cu/MgO catalysts

Hydrogenolysis of biodiesel derived glycerol to 1,2-propanediol (1,2-PDO) has attracted much attention in recent years. In this work, glycerol hydrogenolysis to 1,2-PDO was performed over CuO/MgO catalysts prepared by impregnation and coprecipitation at 180 °C and 3.0 MPa H 2. It was found that the Cu(15)/MgO catalyst prepared by coprecipitation had the best activity. The conversion of glycerol and the selectivity of 1,2-PDO over Cu(15)/MgO reached 72.0% and 97.6%, respectively. And the conversion of glycerol was further increased to 82.0% when small amount of NaOH was added in the reaction mixture. Those highly active catalysts were characterized by X-ray diffraction, transmission electron microscopy, N 2-adsorption and temperature-programmed reduction with H 2. Characterization results revealed that the activity of the prepared catalysts depended strongly on the particle sizes of both Cu and MgO. Catalysts that have smaller sized Cu and MgO particles are more active for glycerol hydrogenolysis.

Microwave-assisted synthesis of nickel nanoparticles

Nickel nanoparticles with uniform, monomorphic self-assembled flower-like microstructure were synthesized by reduction of nickel chloride with hydrazine hydrate in the presence of polyvinylpyrrolidone (PVP) in ethylene glycol under microwave irradiation. An appropriate amount of Na 2CO 3 was necessary for the formation of monomorphic and uniform Ni nanoflowers. Small amount of NaOH and a higher concentration of hydrazine were beneficial to the formation of Ni nanoflowers with a smaller diameter and a narrower distribution. The transmission electron microscopy (TEM) and X-ray diffraction measurements manifested that the as-synthesized Ni nanoflower was the assembles self-organized by hundreds of smaller primary nanoparticles with an average dimension of about 6.3 nm.

Bleaching of Cotton Fabrics by Hydrogen Peroxide with Metallic Ion

In order to establish the bleaching method for cotton fabrics under the neutral or acid condition, the cotton fabrics were pretreated by iron(II) sulfate before subsequent hydrogen peroxide bleaching. The white index and tensile strength at break for yarns from bleached fabrics were measured and considered concerning the pretreated condition by iron(II) sulfate. It was revealed that the high white index attained, by contraries, tensile strength for yarns decreased ca. 20% by processing. However, an addition of a small amount of sodium hydroxide into bleaching bath enabled to depress a decrease of tensile strength for yarns. In addition, it was observed by ESR measurement that an amount of radicals increased when a small amount of NaOH was added into hydrogen peroxide solution in the presence of iron (II) sulfate.

Preparation of Branched Gold Nanocrystals by an Electrochemical Method

Abstract A simple electrochemical method is used for synthesis of branched gold nanocrystals in aqueous solution. The branched nanocrystals can be obtained by electrochemical reduction of AuCl4− in the presence of PVP and a small amount of NaOH. The concentration of NaOH in the solution was found to have a profound influence of branch nanostructure formation.

Solvent effects on the cooperative order–disorder transition of aqueous solutions of schizophyllan, a triple‐helical polysaccharide

A triple helical polysaccharide schizophyllan in aqueous solution exhibited a highly cooperative transition between ordered and disordered states associated with the conformation of its side chains and nearby water molecules. The transition was followed by optical rotation and calorimetry using water containing additives such as NaOH and DMSO as solvents. The ordered state was stabilized or destabilized depending on the kind and amount of the additive employed; in particular, the addition of DMSO had a remarkable stabilizing effect. This effect was analyzed by means of a statistical mechanical theory of linear cooperative transitions, where DMSO was assumed to interact favorably with the ordered side chains. A small amount of NaOH in a solvent mixture stabilized the ordered state and made the transition curve very gradual. No molecular mechanism was elucidated to account for the role of NaOH.

Catalytic activity of faujasite‐type zeolites towards the claus reaction

AbstractCommercial NaY and NaX zeolites showed significant catalytic activity towards the Claus reaction. Bronsted acidity retarded the catalytic activity to a much greater extent than Lewis acidity. Electron Spin Resonance (ESR) spectroscopic studies indicated the formation of SO2− anion radicals on the catalyst surface upon SO2 adsorption. The reactivity of SO2− towards H2S depended upon many factors. When the electron donating property of NaX was increased by impregnation with a small amount of NaOH, the Claus activity was enhanced and the activity of NaX containing 2.0 wt% NaOH was similar to that of a commercial Claus alumina catalyst. Infrared (IR) spectroscopic studies indicated physical and dissociative adsorption of H2S; SO2 was found to chemisorb on the zeolites.

Nitrodan in Feeds

Abstract The anthelmintic, nitrodan, 3-methyl-5(p-nitrophenyl-azo) rhodanine, is extracted from the feed with dimethyl for mamide: ethanol (1 + 1). The intensely absorbing purple solution formed is separated from the residue by suction filtration through a sintered glass funnel. The filtrate is transferred to a volumetric flask, a small amount of NaOH is added, and the solution is brought to volume, Absorbance is measured at 575 mμ, and the amount of nitrodan present is calculated from a standard curve of known concentrations.