Electrosynthesis of eco-friendly electrocatalyst based nickel-copper bimetallic nanoparticles supported on poly-phenylenediamine with highest current density and early ethanol oxidation onset potential

Bimetallic catalysts have been investigated as the most efficient materials to accelerate the chemical transformations at the anode in Direct Ethanol Fuel Cells. A comparative study is presented here to synthesize Ni–Cu bimetallic nanoparticles for the ethanol oxidation reaction on three conducting polymers: poly-ortho-phenylenediamine, poly-meta-phenylenediamine, and poly-para-phenylenediamine. X-ray diffraction (XRD), Scanning Electron Microscopy (SEM), Transmission Electron Microscopy (TEM), and Electrochemical Impedance Spectroscopy (EIS) were used to analyze the modified electrodes. A series of bimetallic Ni–Cu nanoparticles with tunable ratios were successfully synthesized by simply changing the concentrations of Nickel and Copper. It has been confirmed that the best Ni/Cu molar ratio was 25% in the aspect of catalytic performance. The electrocatalyst exhibited an excellent catalytic activity with an anodic current of 70.5 mA cm^?2 at the lowest onset potential of 0.39 V with impressive stability. Ni₄Cu₁/PpPD should be considered as a good alternative to noble metal anode catalyst.     

Formation of single-crystalline BaTiO3 nanorods from glycolate by tuning the supersaturation conditions

We have studied peculiarities in the formation of single-crystalline barium titanate (BaTiO₃) nanorods from a glycolate-mediated complex via a single-step hydrothermal process under different supersaturation (S_R) conditions. X-ray diffraction (XRD) showed the formation of pure BaTiO₃ with an S_R of above 19. The tetragonality for the BaTiO₃ (c/a) reached 1.013 at S_R = 19–29 and dropped to 1.010 for S_R = 39. According to the transmission electron microscopy (TEM) and XRD analyses, the rod-shaped particles exhibited single crystallinity and crystal growth along the [001] plane. With scanning electron microscopy (SEM), the morphological evolution from a plate-shaped intermediate precursor (S_R = 6–9) to a rod-shaped product with an aspect ratio of 6–9 (S_R = 19–29), and to non-polar material with an irregular structure (S_R = 39), was observed. The negative slope, linear dependence of the particles’ width and length on the supersaturation level in the range S_R = 19–39 was established for the first time. The replacement of the prevailing crystallization mechanism from in-situ topotactic transformation into dissolution-precipitation above S_R = 19 was observed. It was shown that with a simple regulation of the S_R, the structural and morphological characteristics of the obtained BaTiO₃ nanoparticle can be effectively tuned.     

Efficiency improvement of CIGS solar cells using RF sputtered TCO/Ag/TCO thin-film as prospective buffer layer

In this paper, TCO (Transparent Conductive Oxide) incorporating ultrathin Ag intermediate film is proposed as a new buffer layer to enhance the efficiency of CIGS thin-film solar cells (TFSCs). In this regard, versatile multilayer thin-films based on ZnO/Ag/ZnO and ITO/Ag/ITO structures were deposited on glass using RF magnetron sputtering technique to determine the optoelectronic parameters of the multilayer structures. The elaborated samples were then characterized using SEM, EDS, XRD, and UV–Visible absorption spectroscopy techniques to investigate the structure morphological, optical, and electronic properties. The deposited multilayer thin-films showed amorphous-like structure and exhibited a broadband absorbance over the visible and even NIR spectrum ranges, indicating its potential application as alternative buffer layers for thin-film solar cells. In this context, TCO/Ag/TCO/CIGS solar cells have been numerically investigated using the deposited multilayer optoelectronic properties. It was revealed that the estimated efficiency of the ZnO/Ag/ZnO/CIGS-based solar cell could reach 18.5% with an open circuit voltage of 0.7 V and a short-circuit current density of 34.8 mA/cm². The performances exhibited by the investigated solar cell demonstrated that ZnO/Ag/ZnO multilayer can be used as an alternative to the conventional CdS buffer layer for developing high-performance non-toxic CIGS solar cells.     

磁性硅铁载铜吸附Hg0动力学机制及密度泛函研究

采用粉末冶金法将纳米单质铜(Cu⁰)、硅铁(FeSi)、四氧化三铁硅涂层(Fe₃O₄@SiO₂)混合煅烧并制备出新型磁性硅铁载铜吸附剂MagFeSi-Cu⁰。实验研究不同烟气温度下MagFeSi-Cu⁰的汞吸附能力基础上,结合颗粒内扩散模型、准二阶动力学模型、Elovich模型及Bangham模型分析了MagFeSi-Cu⁰吸附Hg⁰过程的主要控制步骤。在此基础上,依据密度泛函理论(DFT)研究了不同反应温度下FeSi表面Cu⁰原子与Hg⁰原子的汞齐作用机制。研究结果表明,Bangham模型的拟合值与MagFeSi-Cu⁰汞吸附实验值拟合度最高,MagFeSi-Cu⁰表面痕量Hg⁰吸附由汞的外扩散和表面铜汞齐吸附共同控制;通过密度泛函计算,发现Cu⁰颗粒表面Cu-Hg齐吸附能为-0.534 eV,当烟气温度从80℃上升至200℃时,Hg⁰原子与单质Cu原子的吸附自由能从-22.47 kJ/mol下降至-13.96 kJ/mol,这些结果为深入了解Hg⁰在Cu(111)表面的反应机理提供了理论基础。     

Facile synthesis of asymmetric patchy Janus Ag/Cu particles and study of their antifungal activity

Asymmetric patchy Ag/Cu Janus nanoparticles (NPs) were synthesized via a “seed-mediated” approach. This is the first report of synthesis of nanometer sized metal-based Janus NPs without using complicated methods. Selective adsorption of the surfactant onto the seed NPs leads to the formation of Janus type structure. Subsequently the reduction potential of Ag⁺/Ag⁰ and Cu²⁺/Cu⁰ systems directs the formation of the “patch”. The patchy Janus NPs show significant antifungal activity towards a potent rice pathogen thus offering the prospect of future application in crop protection.     

Fabrication and thermo stability of the SnO2/Ag/SnO2 tri-layer transparent conductor deposited by magnetic sputtering

Using the magnetic sputtering technique, the SnO₂/Ag/SnO₂ tri-layer transparent films were fabricated on float glasses successfully. Compared with the commercial FTO (F-doped SnO₂) film, the SnO₂/Ag/SnO₂ tri-layer films have higher visible-light transmittance and better conductivity. The total thickness of the SnO₂/Ag/SnO₂ films is one third of the commercial FTO film leading to the high visible-light transmittance. The high carrier concentration of the SnO₂/Ag/SnO₂ films contributes to the tri-layer films’ low resistivity. In addition, to further improve the performance of the SnO₂/Ag/SnO₂ tri-layer films, samples were annealed under different temperatures. The results illustrate that the lowest sheet resistance (5.92 Ω/sq) and the highest visible-light transmittance (87.0%) were obtained after annealing at 200 °C. Furthermore, the thermal stability of the films could be enhanced by a multi-step annealing process due to the recrystallization effect.     

Mesoporous electroactive silver doped calcium borosilicates: Structural,antibacterial and myogenic potential relationship of improved bio-ceramics

In this work improved electroactive mesoporous Ag-doped bio-ceramics for medical usages are developed, examining their structural, electrical, in-vitro bioactivity, cell cultures and antibacterial properties against various classical pathogenic bacteria. Ag-containing mesoporous bio-ceramics (MBCs): xmol%Ag₂O - (100-x)[45.8CaO-8.4B₂O₃-45.8SiO₂] where x = 2, 5, 7.5 and 10 were synthesized through a sol-gel method. The small angle X-ray scattering and electron microscopy studies reveal the embedment of silver nanoparticles in the samples. Existence of silver as Ag⁺/Ag⁰ forms in the samples is confirmed by X-ray photoelectron spectroscopy. The N₂ adsorption-desorption analysis evidence the mesoporous structure of the samples. The electrical conductivity of samples increases from 5.4 x 10^?8 S cm^?1 for x = 2 to 1.9 x 10^?6 S cm^?1 for x = 7.5 and then decreases to 0.9 x 10^?6 S cm^?1 for x = 10 at 110 °C. In vitro bioactivity studies revealed that Ag-containing MBCs hold the bone-like hydroxyapatite formation after immersion in human blood plasma like-solution such as Dulbecco's Modi?ed Eagle's Medium. The antibacterial effect of samples against pathogenic bacteria (S. aureus, E. coli, P. monas aeruginosa, and B. cereus) increases with Ag concentration (x = 7.5) and then decreases with Ag content (x = 10). Antibacterial effect is greater for the sample with high electrical conductivity. The cell culture studies evidence not considerable cytotoxic effects for Ag-containing MBCs. Finally, the C2C12 myoblast cell culture studies reveal the significant cell growths and differentiation (myogenesis) for high electrical conducting Ag-containing MBCs.     

CrN和CrN/Ag涂层的真空高温摩擦磨损性能*

为改善涂层在真空、高温等苛刻条件下的摩擦学性能，利用中频直流磁控溅射技术在硅片和316L不锈钢上沉积了CrN和CrN/Ag涂层，利用扫描电镜、透射电镜和X射线衍射仪对涂层的成分及相结构进行了表征，通过划痕测试仪、纳米压痕仪和摩擦磨损试验机测试了涂层的力学及摩擦学性能。结果表明：添加Ag元素以后，CrN/Ag涂层硬度及承载能力有所减小，但结合强度增加；真空高温环境下CrN与CrN/Ag涂层摩擦因数随温度升高呈下降趋势，其中CrN涂层通过软化镀层减小剪切强度和阻力，从而减小摩擦因数，CrN/Ag涂层主要通过高温产生的热驱动力诱导表面Ag润滑膜的形成来减小摩擦因数；CrN涂层依靠自身剪切特性参与摩擦，而CrN/Ag涂层在真空高温下具有自润滑和持续润滑性能，作为自润滑零部件具有潜在的应用价值。     

Enhancement effect of zero-valent iron nanoparticle and iron oxide nanoparticles on dark fermentative hydrogen production from molasses-based distillery wastewater

This study investigates the effect of two different iron compounds (zero-valent iron nanoparticle: nZVI and iron oxide nanoparticles: nIO) and pH on fermentative biohydrogen production from molasses-based distillery wastewater. The nZVI and nIO of optimum particle sizes of 50 nm and 55 nm respectively were synthesized and applied for fermentative hydrogen (H₂) production. The addition of nIO & nZVI at (0.7 g/L, pH: 6) resulted in the highest H₂ yield, H₂ production rate, H₂ content and COD reduction. Moreover, the kinetic parameters of H₂ production potential (P) and H₂ production rate (R_m) increased to 387 mL, and 22.2 mL/h, respectively for nZVI, these values were 363 mL and 21.8 mL/h for nIO. The results obtained indicated the positive effect of nZVI and nIO addition on enhanced fermentative H₂ production. The addition of nZVI & nIO resulted in 71% and 69.4% enhancement in biohydrogen production respectively.