Electrocatalytic Oxygen Reduction Reaction at Silver Nanoparticles (AgNPs) Electrode in Neutral Solution: 5-amino- 2-naphthalene-sulfonic acid (ANS) as a Reducing Agent for AgNPs

We report electrocatalytic oxygen reduction reaction (ORR) at silver nanoparticle (AgNPs) electrodes. The AgNPs was obtained in a general one-pot synthesis using 5-amino 2-naphthalene-sulfonic acid (ANS) as a reducing agent in aqueous and room-temperature conditions. The simultaneous formation of AgNPs and an oxidation of ANS were monitored by UV-vis spectroscopy. Surface morphology of AgNPs was characterized by transmission electron microscopy, which revealed that AgNPs appeared as a sphere. The average size of AgNPs was found to be 162 nm. Furthermore, the chemical identity of the nanostructures was established using X-ray photoelectron spectroscopy and X-ray diffraction. The prepared AgNPs showed electrocatalytic activity for reduction of oxygen in neutral pH. Rotating disk electrode voltammetry was used to elucidate kinetics of ORR at AgNPs electrode. These results reveal that oxygen reduction reaction at AgNPs-PANS electrode involved direct four electron pathways.

Controllable Preparation and Rapid Photoelectric Response of Homogeneous ZnTe Microspheres

With the use of ethylene glycol as a solvent, polyvinylpyrrolidone as a surfactant and hydrazine hydrate as a reducing agent, uniform spherical ZnTe microstructure was synthesized in a homogeneous reactor...

Research on Shrinkage Inhibition Technology of C50 Steel Shell Immersed Tube Self-Compacting Concrete

The effects of shrinkage reducing agent and expansion agent on workability, strength and shrinkage of C50 self-compacting concrete with steel-shell immersed tube were studied. It is found that the expansive agent can increase the 28d compressive strength of concrete and restrain the shrinkage of concrete, but it can reduce the mixture property of concrete, and the shrinkage reducing agent can reduce the 28d compressive strength of concrete, but it can obviously restrain the shrinkage of concrete and improve the performance of concrete mixture. On the basis that the performance of concrete mixture meets the technical index, when the dosage of shrinkage reducing agent is 1.5%, the performance of concrete mixture is the best, and the drying shrinkage rate of 28d is the smallest. At this time, the properties of C50 steel-shell sunk pipe self-compacting concrete are as follows: slump flow 720mm, T50 2s, pour-down time 2s, v-shaped funnel passing time 6s, 28d compressive strength 59.6 MPa, 28d drying shrinkage 135×10−6.

Osmium Recovery as Membrane Nanomaterials through 10–Undecenoic Acid Reduction Method

The recovery of osmium from residual osmium tetroxide (OsO4) is a necessity imposed by its high toxicity, but also by the technical-economic value of metallic osmium. An elegant and extremely useful method is the recovery of osmium as a membrane catalytic material, in the form of nanoparticles obtained on a polymeric support. The subject of the present study is the realization of a composite membrane in which the polymeric matrix is the polypropylene hollow fiber, and the active component consists of the osmium nanoparticles obtained by reducing an alcoholic solution of osmium tetroxides directly on the polymeric support. The method of reducing osmium tetroxide on the polymeric support is based on the use of 10-undecenoic acid (10–undecylenic acid) (UDA) as a reducing agent. The osmium tetroxide was solubilized in t–butanol and the reducing agent, 10–undecenoic acid (UDA), in i–propanol, t–butanol or n–decanol solution. The membranes containing osmium nanoparticles (Os–NP) were characterized morphologically by the following: scanning electron microscopy (SEM), high-resolution SEM (HR–SEM), structurally: energy-dispersive spectroscopy analysis (EDAX), Fourier transform infrared (FTIR) spectroscopy. In terms of process performance, thermal gravimetric analysis was performed by differential scanning calorimetry (TGA, DSC) and in a redox reaction of an organic marker, p–nitrophenol (PNP) to p–aminophenol (PAP). The catalytic reduction reaction with sodium tetraborate solution of PNP to PAP yielded a constant catalytic rate between 2.04 × 10−4 mmol s–1 and 8.05 × 10−4 mmol s−1.

High-yield synthesis of CsPbBr3 nanoparticles: Diphenylphosphine as a reducing agent and its effect in Pb-seeding nucleation and growth

Based on the reported nucleation mechanisms for CsPbX3 and II-VI/IV-VI quantum dots, CsPbBr3 nanoparticles with a high reaction-yield, up to 393% mass-increment, were synthesized by the hot-injection method. The introduction of diphenylphosphine (DPP) as a reducing agent improved nanoparticle nucleation and growth, giving out evidence for Pb-seeding in CsPbBr3 nanoparticles formation. Additionally, a clear influence of the DPP in a CsPbBr3-Cs4PbBr6 incomplete phase transformation was observed, marked by the appearance of several PbBr2 nanoparticles, indicating the need for an improved ratio between the stabilizing agents and the precursors, due to the increased number of nucleation sites produced by the DPP. The resulting CsPbBr3 nanoparticles showed high quality, as they displayed 70%-90% photoluminescence quantum yield (PLQY), narrow size distribution with an average nanoparticle size of ~10 nm and the characteristic cubic morphology reported in previous works. This increment in CsPbBr3 nanoparticles’ reaction yield will contribute to making them a more attractive option for different optoelectronic applications.

Reduction Reactivity of Low Grade Iron Ore-Biomass Pellets for a Sustainable Ironmaking Process

Currently, fossil fuels are still the primary fuel source and reducing agent in the steel industries. The utilization of fossil fuels is strongly associated with CO2 emissions. Therefore, an alternative solution for green steel production is highly recommended, with the use of biomass as a source of fuel and a reducing agent. Biomass’s growth consumes carbon dioxide from the atmosphere, which may be stored for variable amounts of time (carbon dioxide removal, or CDR). The pellets used in this study were prepared from a mixture of low-grade iron ore and palm kernel shells (PKS). The reducing reactivity of the pellets was investigated by combining thermogravimetric analysis (TGA) and laboratory experiments. In the TGA, the heating changes stably from room temperature to 950 °C with 5–15 °C/min heating rate. The laboratory experiments’ temperature and heating rate variations were 600–900 °C and 10–20 °C/min, respectively. Additionally, the reduction mechanism was observed based on the X-ray diffraction analysis of the pellets and the composition of the reduced gas. The study results show that increasing the heating rate will enhance the reduction reactivity comprehensively and shorten the reduction time. The phase change of Fe2O3 → Fe3O4 → FeO → Fe increases sharply starting at 800 °C. The XRD intensities of Fe compounds at a heating rate of 20 °C/min are higher than at 10 °C/min. Analysis of the reduced gas exhibits that carbon gasification begins to enlarge at a temperature of 800 °C, thereby increasing the rate of iron ore reduction. The combination of several analyses carried out shows that the reduction reaction of the mixture iron ore-PKS pellets runs optimally at a heating rate of 20 °C/min. In this heating rate, the reduced gas contains much higher CO than at the heating rate of 10 °C/min at temperatures above 800 °C, which encourages a more significant reduction rate. In addition, the same reduction degree can be achieved in a shorter time and at a lower temperature for a heating rate of 20 °C/min compared to 10 °C/min.

Bimetallic Chitosanstabilized Nanoparticles Ag/Cu, Ag/Co with Fungicidal Properties

Synthesized chitosan stabilized bimetallic nanoparticles Ag/Cu and Ag/Co. It was found that the size and shape of bimetallic nanoparticles can be controlled by varying the concentration of the reducing agent – NaBH4 and the molar ratios of metal ions.Established that an increase in the concentration of the reducing agent, as well as metal ions, promote the formation of fibrillar nanoparticles. It was found that solutions of the synthesized samples effectively suppress the growth and development of the phytopathogen - Fusarium oxysporium forming a sterile zone from 13.3 to 36 mm.

Optimization of the Physical and Mechanical Properties of Grouting Material for Non-Soil-Squeezing PHC Pipe Pile

The physical and mechanical properties of grouting materials greatly affect the friction resistance and the bearing performance of a non-soil-squeezing PHC pipe pile. Orthogonal tests for four factors at five levels were carried out to optimize the proportion of the water–cement mixture by using Portland cement as a raw material and a water-reducing agent, expansion agent and early-strength agent as additives. The following conclusions were obtained: (1) Both the water–cement ratio and the dosage of water-reducing agent are positively correlated with the fluidity of the water–cement mixture and have the greatest influence on the fluidity, followed by the expansion agent and early-strength agent. The saturation point of the water-reducing agent is 1.5%. (2) The strength of the grouting body decreases linearly with the increase of the water–cement ratio, and the dosage of the water-reducing agent has no obvious effect on the strength. As the dosage of expansion agent increases, the strength of the grouting body decreases rapidly. The expansion agent mainly plays a key role in the middle and late stages of the hardening process of the slurry. Early-strength agents have a greater impact on the early strength, but less on the later strength. When the slurry is solidified for 3 h, the early-strength agent has the greatest impact on the strength with an optimal dosage of 5%. (3) The volume of the grouting body has an inverse relationship with the water–cement ratio, and the optimal amount of expansion agent is 12%. The incorporation of an expansion agent makes the volume increase of the grouting body exceed the volume shrinkage ratio caused by the hardening of the grouting body with a curing time of more than 3 days, ensuring a slight increase in the volume of the grouting body. After 3 days, even though the effect of the expansion agent is gradually weakened, it can still ensure that the volume of the grouting body does not shrink. With the increase of the amount of water-reducing agent, the volume of the grouting body gradually decreases. When the amount of water-reducing agent exceeds 1.5%, the volume of the grouting body no longer decreases. (4) The early-strength agent has almost no effect on the volume of the grouting body. When the curing time is 3 h, the water–cement ratio has the greatest influence on the volume of the grouting body, followed by the water-reducing agent, and, finally, the expansion agent. After 3 h, the water–cement ratio still has the greatest influence, and the influence of the expansion agent gradually exceeds that of the water-reducing agent. The water-reducing agent mainly affects the volume of the grouting body in the water separation stage, and the expansion agent mainly plays a role in the middle and late stages of the slurry solidification. After optimized ratio analysis, the fluidity of the water–cement mixture can be improved, the volume shrinkage ratio rate can be lowered and the early strength can be increased.