Non-metal Oxides Research Articles

Myco-decontamination of azo dyes: nano-augmentation technologies.

Effluents of textile, paper, and related industries contain significant amounts of synthetic dyes which has serious environmental and health implications. Remediation of dyes through physical and chemical techniques has specific limitations. Augmented biological decontamination strategies 'microbial remediation' may involve ring-opening of dye molecules besides the reduction of constituent metal ions. Both bacterial and fungal genera are known to exhibit metabolic versatility which can be harnessed for effective bio-removal of the toxic dye contaminants. Ascomycetous/basidiomycetes fungi can effectively decontaminate azo dyes through laccase/peroxidase enzyme-mediated catalysis. The extent, efficacy, and range of fungal dye decontamination can be enhanced by the conjugated application of nanomaterials, including nanoparticles (NPs) and their composites. Fungal cell-enabled NP synthesis- 'myco-farmed NPs', is a low-cost strategy for scaled-up fabrication of a variety of metal, metal oxide, non-metal oxide NPs through oxidation/reduction of dissolved ions/molecules by extracellular biomolecules. Augmented and rapid decontamination of azo dyes at high concentrations can be achieved by the use of myco-farmed NPs, NPs adsorbed fungal biomass, and nano-immobilized fungi-derived bio-catalytical agents. This manuscript will explore the opportunities and benefits of mycoremediation and application of fungus-NP bionanoconjugate to remediate dye pollutants in wastewaters and land contaminated with the effluent of textile industries.

Beyond CO2 Reduction: Vistas on Electrochemical Reduction of Heavy Non-metal Oxides with Very Strong E-O Bonds (E = Si, P, S).

The carbon dioxide reduction reaction (CO2RR), in particular electrochemically, to produce carbonaceous fuels is considered as a viable approach to store energy and to enable a CO2-neutral carbon management. Besides CO2RR, there is an additional strong demand for benign electrochemical reduction of other important heavy non-metal oxo species (e.g., SiO2, phosphine oxides, SO2) with thermodynamically stable E-O bonds, which accrue in large quantities in industry. In this respect, the energy-intense deoxygenation of oxo compounds of silicon, phosphorus, and sulfur is of particular technological importance because they represent some of the main feedstocks to produce important molecules and functional materials. For example, the release of elemental silicon, phosphorus (P4), and sulfur (S8) from naturally occurring minerals (e.g., silicate, phosphate, sulfate) follows energy-intensive chemical routes. Thus, the established chemical reduction routes to deoxygenate such oxo precursors produce tons of reagent waste or, in the case of carbothermal treatment of minerals, afford a lot of CO2. On the contrary, electrochemical strategies developed for the selective deoxygenation of E-O compounds remain as a feasible alternative powered by renewable electricity instead of fossil energy. Moderate reaction conditions, a large scope in experiment design for selective reactions, easy product isolation, and zero reagent waste by applying electrochemical methods offer a promising solution to overcome the drawbacks of chemical reduction routes. This Perspective summarizes the emergence of electrochemical strategies developed for the reduction of selected examples of E-O/E═O compounds with E = silicon, phosphorus, and sulfur in the past few decades and highlights opportunities and future challenges.

Enhancing the gas separation properties of mixed matrix membranes via impregnation of sieve phases with metal and nonmetal promoters

In recent years, numerous studies investigated influence of many different sieves on gas separation performance of mixed matrix membranes (MMMs), but few studies have investigated effects of morphology of sieve phases. Herein, we used two transition metal oxides, based on manganese (Mn) and iron (Fe), and also a nonmetal oxide, based on phosphorus (P), as modifier agents in impregnation process of ZSM-5 nanoparticles. These metal/nonmetal oxides are briefly named promoters. Influence of the impregnated ZSM-5 nanoparticles on separation performance of PEBA/ZSM-5 MMMs were investigated, [PEBA: polyether block amide]. Morphological changes made during the impregnation process considerably affected the gas separation properties of the MMMs. ZSM-5 nanoparticles impregnated with Mn, Mn-ZSM5, showed a separation performance beyond that of the parent ZSM-5 nanoparticles. Compared to the parent, Mn-ZSM-5 at the highest loading content, 9 wt%, increased the CO2 permeability by 44%, while CO2/CH4 and CO2/N2 selectivity values respectively enhanced from 22.7 and 48.8 to 33.3 and 52.2. Our results confirmed that impregnation of sieve phases with metal promoters can be considered as a reliable approach to provide a general toolbox for improving the gas separation performance of membranes bearing molecular sieve phases.

Unique silica biomimetic mineralization of acidic elastin-like polypeptides without hydroxyl and charged residues

Elastin-like polypeptides (ELPs), usually as a purification-tag, can be easily expressed and rapidly purified. We found ELPs[V9F-40], which did not contain hydroxyl or charged residues with the pI of 5.52, could biomimetically form silica when they were in ordered structure. The specific activity of ELPs[V9F-40] was 70.89 ± 9.53. Besides, the time needed for the completion of biomimetic silicification was about 138 s, which was only 1/3 of that for other reported peptides. The ELPs@silica is mainly spherical and the sizes of them were around 900 nm. However, currently presented mechanisms for peptide-triggered silica biomimetic mineralization could not explain such unique phenomenon. It would pave a new way for mining or designing peptides with such function, which provide a potential green method for the preparation of biomimetic silica particles. It would endow ELPs more functions and expand the application fields of ELPs such as the bioinspired synthesis of peptide biotemplated metal or nonmetal oxide nanoparticles.

Inorganic nanorings and nanotori: State of the art

Abstract

The Application of Passive Radiative Cooling in Greenhouses

At present, greenhouses are used to grow a variety of crops around the world. However, with the change of climate, the increasingly harsh weather makes it more and more disadvantageous for people to work inside, and plants are difficult to grow. Previous research has illustrated that radiative cooling can be realized by using certain nonmetal oxide particles created for emission in an infrared atmospheric transparency window, which is an environmentally friendly cooling method due to reducing energy consumption. Polyethylene (PE)-based formulations with a UV stabilizer and nonmetal oxide particles (NOP) were first granulated and then formed a monolayer film by co-injection molding. The experimental results show that due to passive radiative cooling, under the environmental conditions of 35 °C, and only considering the natural convection heat transfer, the net cooling power of the greenhouse film developed in this study is 28 W·m−2 higher than that of the conventional PE film. The temperature inside the simulated greenhouse cladded with the new greenhouse covering was on average 2.2 °C less than that of the greenhouse with the conventional PE film.

Submicron inorganic particles as an additional filler in hybrid epoxy matrix composites reinforced with glass fibres

In this study, the effect of selected submicron metal oxide (zinc oxide, titanium oxide) or non-metal oxide (silicon dioxide) particles on mechanical and thermo-mechanical properties of epoxy/glass composites was investigated. The applied epoxy resin was a diglycidyl ether of bisphenol-A cured with triethylenetetramine. As a reinforcement twill weave E-glass fabric was used. Hybrid composites (contained particulate and fibrous filler) were fabricated by using the hand lay-up method and the average content of glass fibres was 39–41 wt%. Flexural properties, thermo-mechanical properties, abrasion resistance and hardness were determined for each group of the prepared hybrid epoxy/glass composites. The obtained results were compared with control samples (without submicron particles). Investigations showed that the addition of 2 wt% SiO2, 4 wt% TiO2 or 4 wt% ZnO to epoxy resin improved the flexural strength and the flexural modulus of composites. Dynamic mechanical analysis showed that the addition of the mentioned particles enhanced storage and loss modulus. It can be attributed to the good dispersion and good interaction between submicron-mentioned particles and the epoxy matrix.

Controlled synthesis of hollow multishelled structures by sequential templating approach

The hollow multi-shelled structure (HoMS) has at least two separated shells spatially ordered from outside to inside. This unique, temporal-spatial ordered structure endows an abundance of beneficial physicochemical properties, including high surface-to-volume ratios, short mass transport lengths and high loading capacities. Due to these favorable properties, the HoMS has been recognized as one of the most promising candidates for many potential applications, including electrochemical energy storage, solar energy conversion, electromagnetic wave absorption, catalysis, gas detection, and drug delivery. However, for a long time, achieving general and controllable synthesis of the HoMS, using conventional soft-templating or hierarchical self-assembly methods, has remained a great challenge, due to the complexity of the structure. This has limited the development and application of novel functional materials. Thus, in this article, we turn our heads to the development of the sequential templating approach (STA), which has greatly enriched both the compositional diversity and the geometrical diversity of the HoMS, leading to more controllable and applicable HoMS. Here, we first review the development process and characteristics of the STA for the synthesis of the HoMS. The STA, which was first reported by our research group and then further developed by others, has proven to be a universal and controllable technique to building HoMS with diverse compositions and structures. The essence of this approach is that the template can play a role of “multiple and sequential templating” during the removal process, and the precursors incorporating the template are then aggregated, solidified, and crystallized to gradually form rigid multiple shells. The STA has several attractive advantages: (1) There are no limitations on the composition or shape of the template. In addition to the most commonly used carbonaceous microspheres, other shapes and compositions such as polymers, metal-organic frameworks, and metal carbonates can also be used as the template for fabricating the HoMS. (2) The approach is universally applicable to the controlled synthesis of single, dual, multicomponent and heterogeneous HoMS with various compositions, such as metal oxides, non-metal oxides, metal carbonates, metal sulfides, metal phosphides, etc. (3) Templates can enrich precursors through many different methods, such as ion adsorption, ion exchange, precipitation reaction, and electrostatic spray. Remarkably, electrostatic spray, which indicates a simultaneous occurrence of template formation and precursor enrichment, is accessible for achieving large-scale HoMS production. Finally, we discuss the emerging challenges and future research directions of the HoMS. In-depth investigation on the basic reaction mechanism involved in the synthesis and manipulation of HoMS can guide researchers to develop improved designs and syntheses of the HoMS, in order to better fulfill the different requirements of specific applications.

'Smoging kills' - Effects of air pollution on human respiratory system.

Atmospheric pollution suspended in humid air is popularly known as 'smog'. It is composed of dust particles of different sizes, as well as non-metal oxides, organic compounds, and heavy metals. Exposure to harmful substances suspended in the air - apart from, for example - smoking cigarettes, one of the modifiable factors leading to the development of respiratory diseases. There are six types of substances present in the air that have a negative impact on public health and result in significant consequences: ozone, particulate matter (PM) of different diameters - PM2.5µ, PM2.5‒10 µ, PM10 µ, nitrogen dioxide, sulphur dioxide, carbon monoxide and lead. Particular attention is given to small dust particles (PM10 and PM2.5) because they can penetrate into the lower respiratory tract. Apart from describing the composition of smog and sources of air pollution, the article also discusses the impact of atmospheric pollutants on both development and aggravation of the symptoms of such respiratory tract diseases as asthma, chronic obstructive pulmonary disease, respiratory infections and lung cancer. Some of legal measures applied in different countries aimed at reducing exposure to noxious air pollutants are reviewed. The authors believe that the increased focus on risks arising from inhaling toxic air pollution may be a first step for developing systemic solutions aimed at resolving or, at least, decreasing those risks.

Gold/oxide heterostructured nanoparticles for enhanced SERS sensitivity and reproducibility

In surface-enhanced Raman scattering (SERS), it is highly desirable to obtain Raman signals with high sensitivity and reproducibility from noble metal nanoparticle substrates, which remains a great challenge due to the inhomogeneity of the plasmonic coupling that is sensitive to the interparticle nanogaps. In this work, we report that the interparticle plasmonic coupling could be circumvented by first synthesizing Au/metal or nonmetal oxide heterostructured nanoparticles and then depositing them uniformly onto the substrates, leading to high reproducibility of the Raman signals. Strong plasmonic coupling has been found at the Au/oxide interface, which enables high sensitivity of the SERS analysis that accompanies the excellent signal reproducibility. Among different oxides investigated (SiO2, TiO2 and Fe2O3), the Au/Fe2O3 heterostructured nanoparticles demonstrate the highest Raman enhancement effect. We believe our strategy opens a promising route to fabricate SERS substrates that are capable of sensitively and quantitatively detecting molecules of interest in a much reliable manner.

Research Progress on Surface Coating Layers on the Positive Electrode for Lithium Ion Batteries

Lithium ion batteries (LIBs) are one of the most promising secondary batteries due to their advantages including long cycle life, high energy density, limited self-discharge, high operating voltage and environmental friendliness. The development of electrode materials is crucial for the further application of LIBs. There are many effective ways to enhance the performance of positive electrode materials of LIBs such as surface coating, ion doping, preparation of composite materials and nanosized materials and so forth. Among them, surface coating is considered to be a promising way to improve the electrochemical performance of LIBs. Surface coating can normally form a physical barrier or a doped surface layer to play favorable roles for the electrode materials, such as hindering side reactions between positive electrode materials and the electrolyte. In this paper, different kinds of surface coating layers will be discussed according to previous research, including carbon materials, metal oxides, metal fluorides, metal phosphates, nonmetal oxides, electrode materials coating layer, hybrid coating layer, polymer and so forth. In addition, the mechanism of these coating materials will be summarized, and the future development will be discussed in this paper.

Carbon nitride, metal nitrides, phosphides, chalcogenides, perovskites and carbides nanophotocatalysts for environmental applications

Effective technologies and materials are needed for environmental detoxification and clean energy production. The actual photocatalytic technology is largely dependent on metal oxide-based semiconductors, which have issues such as cost, limited spectral response and recombination problems. Alternatively, non-metal photocatalysts have recently emerged. This article reviews non-metal oxide photocatalytic materials such as carbon nitride, metal nitrides, phosphides, chalcogenides, perovskites and carbides for environmental clean-up and energy production.

Biochemical synthesis of gold nanoparticles from leaf protein of Nicotiana tabacum L. cv. xanthi and their physiological, developmental, and ROS scavenging responses on tobacco plant under stress conditions.

The stress conditions imposed by the impact of metal and non-metal oxide nanoparticles over plant systems enhances the synthesis of reactive oxygen species (ROS), resulting in oxidative damage at cellular level. The objective of this study was to synthesise the gold nanoparticles (GNps) from the leaves protein of Nicotiana tabacum L. cv. xanthi, its characterisation, and response on plant physiology and ROS scavenging activity on plants after exposure to different stresses. The authors have treated N. tabacum L. cv. xanthi plants with 100, 200, 300, 400, and 500 ppm biochemically synthesised GNps and examined physiological as well as biochemical changes. Results showed that biochemically synthesised GNps exposure significantly increased the seed germination (P < 0.001), root (P < 0.001), shoot growth (P < 0.001), and antioxidant ability (P < 0.05) of plants depending on bioengineered GNPs concentrations. Low concentrations (200-300 ppm) of GNps boosted growth by ∼50% and significantly increase in photosynthetic parameters such as total chlorophyll content (P < 0.05), membrane ion leakage (P < 0.05) as well as malondialdehyde (P < 0.05) content with respect to untreated plants under stress conditions. The high concentration (400-500 ppm) of GNps affected these parameters in a negative manner. The total antioxidant activity was also elevated in the exposed plants in a dose-dependent manner.

Evaluation of Functional SiO₂ Nanoparticles Toxicity by a 3D Culture Model.

as a kind of non-metal oxide SiO2 NPs have been extensively used in biomedicine, pharmaceuticals and other industrial manufacturing fields, such as DNA delivery, cancer therapy… Our group had developed a method based on microemulsion process to prepare SiO2 NPs incorporating photonic or magnetic nanocrystals and luminescent nanosized inorganic metal atom clusters. However, the toxicity of nanoparticles is known to be closely related to their physico-chemical characteristics and chemical composition. it is therefore of interest to investigate the toxicity of these novel SiO2 NPs to the cells that may come in contact. the potential toxic effect of the functional @SiO2 NPs containing Mo6 clusters with or without gold nanoparticles was investigated, at concentrations 1 μg/mL, 10 μg/mL and 100 μg/mL each, on three different cell lines. Cell viability was measured by the MTT test in monolayer's culture whereas the cytotoxicity in spheroid model was examined by the APH assay. In a second time, oxidative-stress-induced cytotoxicity was investigated through glutathione levels dosages. the results indicated that both A549 and L929 cell lines did not exhibit susceptibility to functional @SiO2 NPs-induced oxidative stress unlike KB cells. SiO2 NPs containing CMB may become toxic to cultured cells but only at a very high dosage level. Therefore, this toxicity depends on cell lines and more, on the model of cell cultures. The selection of appropriate cell line remains a critical component in nanotoxicology. these results are relevant to future applications of SiO2 gold-cluster NPs in controlled release applications.

(Invited) New Photoanode Materials for Photoelectrochemical Water Splitting

The direct photoelectrochemical (PEC) splitting of water into hydrogen and oxygen remains a promising route for producing sustainable and renewable hydrogen fuel. PEC devices use both photocathodes for the hydrogen generation (p-type semiconductors) and photoanodes for the oxygen evolution (n-type semiconductors), respectively. From chemical stability concerns, n-type metal oxides and p-type non-metal oxides are the desirable photoelectrodes. Unfortunately, none of the current existing metal oxides have demonstrated high solar-to-hydrogen conversion efficiencies under visible light irradiation, due largely to the fact that most metal oxides have too large bandgaps to effectively absorb the main portion of the sunlight spectrum, i.e., visible light. It is essential to engineer the bandgaps of metal oxides for the applications of PEC water splitting. For p-type photocathodes, most considered materials such as CuInS2, Cu(In,Ga)Se2, CuZnSnS4 (CZTS) and WSe2 have bandgap not wide enough or have poor performance when their bandgaps are widened. In this talk, I will present our recent results on two new PEC materials, one metal oxide (barium bismuth niobate) and one non-metal oxide (copper barium tin sulfide). Through density-functional theory (DFT) and experimental synthesis, we demonstrate a new approach to effectively engineer the bandgap of barium bismuth niobate double perovskites (Ba2Bi1+xNb1-xO6), i.e, varying the composition. We find that the film with the composition of Ba2Bi1.4Nb0.6O6 forms single pure phase and exhibits a nearly direct bandgap of about 1.64 eV, which is small enough to absorb visible light at wavelengths below 756 nm. For copper barium tin sulfide (CBTS), our DFT calculations indicate that it exhibits much better defect tolerance than CZTS. Our preliminary results show a saturated photocurrent of ~11 mA cm-2 were reached at -0.55 V vs RHE in a neutral electrolyte.

Recycling of spent lithium-ion battery with polyvinyl chloride by mechanochemical process

In the present study, cathode materials (C/LiCoO2) of spent lithium-ion batteries (LIBs) and waste polyvinyl chloride (PVC) were co-processed via an innovative mechanochemical method, i.e. LiCoO2/PVC/Fe was co-grinded followed by water-leaching. This procedure generated recoverable LiCl from Li by the dechlorination of PVC and also generated magnetic CoFe4O6 from Co. The effects of different additives (e.g. alkali metals, non-metal oxides, and zero-valent metals) on (i) the conversion rates of Li and Co and (ii) the dechlorination rate of PVC were investigated, and the reaction mechanisms were explored. It was found that the chlorine atoms in PVC were mechanochemically transformed into chloride ions that bound to the Li in LiCoO2 to form LiCl. This resulted in reorganization of the Co and Fe crystals to form the magnetic material CoFe4O6. This study provides a more environmentally-friendly, economical, and straightforward approach for the recycling of spent LIBs and waste PVC compared to traditional processes.

Probing the interactions between lignin and inorganic oxides using atomic force microscopy

Understanding the interactions between lignin and inorganic oxides has both fundamental and practical importance in industrial and energy fields. In this work, the specific interactions between alkali lignin (AL) and three inorganic oxide substrates in aqueous environment are quantitatively measured using atomic force microscopy (AFM). The results show that the average adhesion force between AL and metal oxide such as Al2O3 or MgO is nearly two times bigger than that between AL and nonmetal oxide such as SiO2 due to the electrostatic difference and cation-π interaction. When 83% hydroxyl groups of AL is blocked by acetylation, the adhesion forces between AL and Al2O3, MgO and SiO2 decrease 43, 35 and 75% respectively, which indicate hydrogen bonds play an important role between AL and inorganic oxides, especially in AL-silica system.

Variation in Crystalline Phases: Controlling the Selectivity between Silicon and Silicon Carbide via Magnesiothermic Reduction using Silica/Carbon Composites

Magnesiothermic reduction of various types of silica/carbon (SiO2/C) composites has been frequently used to synthesize silicon/carbon (Si/C) composites and silicon carbide (SiC) materials, which are of great interest in the research areas of lithium-ion batteries (LIBs) and nonmetal oxide ceramics, respectively. Up to now, however, it has not been comprehensively understood how totally different crystal phases of Si or SiC can result from the compositionally identical parent materials (SiO2/C) via magnesiothermic reduction. In this article, we propose a formation mechanism of Si and SiC by magnesiothermic reduction of SiO2/C; SiC is formed at the interface between SiO2 and carbon when silicon intermediates, mainly in situ-formed Mg2Si, encounter carbon through diffusion. Otherwise, Si is formed, which is supported by an ex situ reaction between Mg2Si and carbon nanosphere that results in SiC. In addition, the resultant crystalline phase ratio between Si and SiC can be controlled by manipulating the synthe...

A Review on Metallic Ion and Non-Metal Doped Titania and Zinc Oxide Photo-Anodes for Dye Sensitized Solar Cells

A Review on Metallic Ion and Non-Metal Doped Titania and Zinc Oxide Photo-Anodes for Dye Sensitized Solar Cells

ChemInform Abstract: A Review on Advances in Photocatalysts Towards CO2 Conversion

AbstractReview: 224 refs.