Overview on multicomponent ceramic composite materials used for efficient photocatalysis – An update

Water is an important item for the survival of humans, animals and plants in the planet earth. In the industrialized world, water pollution is raising every day, mainly in the textile, paper, medicine, and plastic production industries. Pollution from coloured compounds is primarily identified as being the major threat to wastewater. In the absence of any pre-treatment, substituted phenols, dyes and agricultural wastes seriously contaminate groundwater systems. For the removal of dyes from the industrial waste water, the following three traditional methods are used: chemical, physical and biological but, the cost of the methods little high. For alternation of these methods, now a days photocatalytic degradation method was used. Metal and metal oxide nanoparticles are excellent catalysts for reducing and degrading aqueous phase nitro compounds and aromatic dyes. Nanoparticles are commonly assembled into two types, i.e., organic (carbon nanoparticles) and inorganic (metal, semiconductor and magnetic nanoparticles) nanoparticles. In this review article we are mainly focused on the behaviour of different types of pure metal oxides and metal oxide@metal/metal oxide/carbon/polymer nanocomposites for the removal of various organic pollutants from water and their efficiency has been reported. As a result of their review the cerium-based metal oxides such as CdS/CeO₂, CeO₂/Y₂O₃, GQDs/CeO₂ and Ag/cellulose@CeO₂/QDs shows more degradation efficiency (above~95%) towards the organic pollutants when compared to other metal oxides.     

A generalized technique for the encapsulation of nano‐sized NiO particles by styrene‐2‐hydroxyethyl methacrylate copolymer

Encapsulation of nickel oxide (NiO) particles is of great interest to the researchers as such modification produces remarkable improvement in properties and versatility in application potential. In this investigation, nanosized NiO particles were first prepared by calcination of nickel hydroxide precursor obtained using a simple liquid‐phase process. The produced NiO particles were stabilized with oleic acid and then treated with tetraethylorthosilicate to produce NiO/SiO₂ composite seed particles. Finally tri‐layered inorganic/organic composite particles were prepared by seeded copolymerization of styrene and 2‐hydroxyethyl methacrylate (HEMA) in the presence of NiO/SiO₂ composite seed particles. The produced composite particles named as NiO/SiO₂/P(S‐HEMA) were colloidally stable, and the obtained particles were characterized by Fourier transform infrared spectroscopy, scanning electron microscopy, X‐ray diffraction, X‐ray photoelectron spectroscopy and thermogravimetric analyses. Copyright © 2015 John Wiley & Sons, Ltd.     

Functional Nickel Oxide Nanostructures for Ethanol Oxidation in Alkaline Media

Nickel oxide (NiO) nanostructures are employed in the basic medium for the oxidation of ethanol. A variety of NiO nanostructures are synthesized by wet chemical growth method, using different hydroxide (OH^?) ion sources, particularly from ammonia, hexamethylenetetramine, urea and sodium hydroxide. The use of urea as (OH^?) ion source results in flower‐like NiO structures composed by extremely thin nanowalls (thickness lower than 10 nm,), which demonstrated to be the most active for ethanol oxidation. All the samples exhibit NiO cubic phase, and no other impurity was detected. The cyclic voltammetry (CV) curves of NiO nanostructures were found linear over the concentration range 0.1–3.5 mM (R²=0.99) of ethanol, with the limit of detection estimated to be 0.013 mM for ethanol. The NiO nanostructures exhibit a selective signal towards ethanol oxidation in the presence of different members of alcohol family. The proposed NiO nanostructures showed a significant practicality for the reproducible and sensitive determination of ethanol from brandy, whisky, mixture of brandy and rum, and vodka samples. The nanomaterial was used as a surface modifying agent for the glassy carbon electrode and it showed a stable electro‐oxidation activity for the ethanol for 16 days. These findings indicate that the presented NiO nanomaterial can be applied in place of noble metals for ethanol sensing and other environmental applications (like fuel cells).     

Green synthesis and characterizations of Nickel oxide nanoparticles using leaf extract of Rhamnus virgata and their potential biological applications

In the present report, Nickel oxide nanoparticles (NiONPs) were synthesized using Rhamnus virgata (Roxb.) (Family: Rhamnaceae) as a potential stabilizing, reducing and chelating agent. The formation, morphology, structure and other physicochemical properties of resulting NiONPs were characterized by Ultra violet spectroscopy, X‐ray diffraction (XRD), Fourier Transform Infrared analysis (FTIR), Scanning electron microscopy (SEM), Energy‐dispersive‐spectroscopy (EDS), Transmission electron microscopy (TEM), Raman spectroscopy and dynamic light scattering (DLS). Detailed in vitro biological activities revealed significant therapeutic potential for NiONPs. The antimicrobial efficacy of biogenic NiONPs was demonstrated against five different gram positive and gram negative bacterial strains. Klebsiella pneumoniae and Pseudomonas aeruginosa (MIC: 125 μg/mL) were found to be the least susceptible and Bacillus subtilis (MIC: 31.25 μg/mL) was found to be the most susceptible strain to NiONPs. Biogenic NiONPs were reported to be highly potent against HepG2 cells (IC₅₀: 29.68 μg/ml). Moderate antileishmanial activity against Leishmania tropica (KMH₂₃) promastigotes (IC₅₀: 10.62 μg/ml) and amastigotes (IC₅₀: 27.58 μg/ml) cultures are reported. The cytotoxic activity was studied using brine shrimps and their IC₅₀ value was recorded as 43.73 μg/ml. For toxicological assessment, NiONPs were found compatible towards human RBCs (IC₅₀: > 200 μg/ml) and macrophages (IC₅₀: > 200 μg/ml), deeming particles safe for various applications in nanomedicines. Moderate antioxidant activities: total antioxidant capacity (TAC) (51.43%), 2,2‐diphenyl‐1‐picrylhydrazyl (DPPH) activity (70.36%) and total reducing power (TRP) (45%) are reported for NiONPs. In addition, protein kinase and alpha amylase inhibition assays were also performed. Our results concluded that Rhamnus virgata synthesized NiONPs could find important biomedical applications with low cytotoxicity to normal cells.     

Nickel(II) cluster‐based mixed‐cation coordination polymer synthesized from 2‐mercaptobenzoic acid and its application

High‐nuclearity metal clusters have received considerable attention not only because of their diverse architectures and topologies, but also because of their potential applications as functional materials in many fields. To explore new types of clusters and their potential applications, a new nickel(II) cluster‐based mixed‐cation coordination polymer, namely poly[hexakis[μ₄‐(2‐carboxylatophenyl)sulfanido]di‐μ₃‐chlorido‐tri‐μ₂‐hydroxido‐octanickel(II)sodium(I)], [Ni₈NaCl₂(OH)₃(C₇H₄O₂S)₆]_n, 1 , was synthesized using nickel chloride hexahydrate and mercaptobenzoic acid (H₂mba) as starting reactants under hydrothermal conditions. The material was characterized by single‐crystal X‐ray diffraction (SCXRD), Fourier transform IR spectroscopy, thermogravimetric analysis, powder X‐ray diffraction and X‐ray photoelectron spectroscopy analysis. SCXRD shows that 1 consists of a hexanuclear nickel(II) [Ni₆] cluster, dinuclear Ni^II nodes and a mononuclear Na^I node, resulting in the formation of a complex covalent three‐dimensional network. In addition, a tightly packed NiO/C&S nanocomposite is fabricated by sintering the coordination precursor at 400 °C. The uniform nanocomposite consists of NiO nanoparticles, incompletely carbonized carbon and incompletely vulcanized sulfur. When used as a supercapacitor electrode, the synthesized composite shows an extra‐long cycling stability (>5000 cycles) during the charge/discharge process.     

Na或Cu掺杂对Si/NiO异质结的光电性能影响

利用磁控溅射方法制备了引入Na或Cu元素前后Si/NiO异质结。实验结果表明，Na元素引入后的Si/NiO：Na异质结的整流特性最佳。此时，Si/NiO：Na异质结光学透过率可以达到70%，这可能是由于Si/NiO：Na异质结的结晶质量较优、薄膜内缺陷少所致。Si/NiO：Na异质结I-V曲线的拟合结果显示界面态状态也会影响其整流特性。而Si/NiO和Si/NiO：Cu异质结都没能获得较好的整流特性，可能是薄膜内缺陷增多所致。这一结论得到了XRD、SEM、AFM和UV结果的支持。     

Preparation and characterization of NiO nanoparticles from thermal decomposition of the [Ni(en)3](NO3)2 complex: A facile and low-temperature route

NiO nanoparticles with an average size of 15 nm were easily prepared via the thermal decomposition of the tris(ethylenediamine)Ni(II) nitrate complex [Ni(en)₃](NO₃)₂ as a new precursor at low temperature, and the nanoparticles were characterized by thermal analysis (TGA/DTA), X-ray diffraction (XRD), Fourier-transformed infrared spectroscopy (FT-IR), UV-Vis spectroscopy, BET specific surface area measurement, scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDX), transmission electron microscopy (TEM) and magnetic measurements. The magnetic measurements confirm that the product shows a ferromagnetic behavior at room temperature, which may be ascribed to a size confinement effect. The NiO nanoparticles prepared by this method could be an appropriate photocatalytic material due to a strong absorption band at 325 nm. This method is simple, fast, safe, low-cost and also suitable for industrial production of high purity NiO nanoparticles for applied purposes.     

助剂CuO和La2O3对NiO/α-Al2O3甲烷催化部分氧化制合成气引发过程的影响

采用分步浸渍法制备了NiO/α-Al₂O₃、NiO-CuO/α-Al₂O₃和NiO-La₂O₃/α-Al₂O₃三种催化剂,运用程序升温表面反应（TPSR）技术考察了助剂CuO和La₂O₃对NiO/α-Al₂O₃甲烷催化部分氧化（CPOM）反应引发过程的影响。结果表明,无论是否经过预还原处理,NiO/α-Al₂O₃催化剂在CH₄/O₂混合气氛下进行程序升温表面反应（CH₄/O₂-TPSR）时,即使升高到910℃也不能引发CPOM反应。添加助剂CuO或La₂O₃后,NiO-CuO/α-Al₂O₃和NiO-La₂O₃/α-Al₂O₃催化剂在CH₄/O₂-TPSR过程中均可以引发CPOM反应。原因分别是CuO促进了CH₄对NiO的还原以及抑制了O₂对Ni0的再氧化,La₂O₃减小了Ni晶粒粒径和还原时扩散阻力促进NiO的还原。     

反应物的变化对吸附相反应技术制备NiO/SiO2的影响

以SiO2为载体,研究反应物种类和浓度对吸附相反应技术制备NiO粒子的影响。首先采用滴定法测定了各个反应物在载体表面的吸附过程,利用TEM、XRD分析,对比了不同反应物制备得到的NiO粒子的形貌。在确定了反应物的基础上,进一步设计了2种水量下制备实验,研究反应物浓度对粒子形貌的影响。XRD结果表明,1.0mL水量下NiO粒子的晶粒粒径随着反应物浓度增加先缓慢减少后增大。而随反应物浓度增加,5.0mL水量得到的粒子晶粒粒径则一直变大。2种吸附层中不同的反应速率使得相同条件下,高水量(5.0mL)得到的NiO粒子粒径要小于1.0mL水量下得到的粒子。物理吸附层中形成的粒子与载体结合力较弱,使得焙烧后5.0mL水量下得到的粒子在SiO2上分布不均匀。