Metal Oxide Composites Research Articles

Effect of transformation temperature toward optical properties of derived CuO/ZnO composite from Cu–Zn hydroxide nitrate for photocatalytic ciprofloxacin degradation

In this work, visible light driven CuO/ZnO photocatalyst composite derived from Cu–Zn hydroxide nitrate (CuZn–HN) was fabricated via thermal transformation at varying temperatures. The effect of temperature on their morphology and optical properties was examined. The CuZn–HN calcined at 400 °C (400HN) showed the better performance than 200HN, 800HN and uncalcined CuZn–HN in terms of the photocatalytic oxidation rate for Ciprofloxacin (CIP) degradation under visible light irradiation conditions. The improved photocatalytic performance of 400HN could resulted from the combination of narrow energy band gap, suppressed photogenerated e−-h+ recombination, and strong interactions between CIP and the composite' surface. The finding suggested the transformation temperature of CuZn–HN to CuO/ZnO composite is a key factor to produce the highly effective photocatalyst with the simple protocol as an alternative synthetic method to prepare the mixed metal oxide composites. Moreover, the photocatalytic CIP degradation pathway was elucidated by GC-MS analysis, and the charge transfer mechanism in CuO/ZnO composite was also proposed.

The role of CuO/TS-1, ZnO/TS-1, and Fe2O3/TS-1 on the desalination performance and antifouling properties of thin-film nanocomposite reverse osmosis membranes

The thin-film nanocomposite reverse osmosis (TFN-RO) membranes were prepared by the introduction of hydrophilic nanoparticles into the polyamide (PA) layer to improve desalination performance. First, the hydrothermal method was used to synthesize titanium silicate-1 (TS-1) as a base additive for the fabrication of the TFN-RO membrane. Since the particle size has a significant effect on its dispersion in the membrane matrix, changing the nucleation rate of TS-1 precursor solution with a simple method conducted to reduce the size of TS-1. Then metal oxide composites were prepared via the wet impregnation method. FESEM and AFM analyses were performed to investigate the surface alteration of the membranes due to the introduction of nanoparticles. The results showed that the surface of the TFN membranes was smoother than the unmodified one. To assess the changes in membrane properties after incorporating additives, the water contact angle, and zeta potential were measured. Compared to TFC, the 0.02TS1-Fe-TFN membrane had a ∼ 30% increase in pure water flux. Meanwhile, the rejection of NaCl increased from ∼ 95% to ∼ 99%. The probing of antifouling performance using bovine albumin serum (BSA) and humic acid (HA) contaminants also showed that due to reduced roughness, the modified membranes had higher fouling resistance than TFC. Also, the TFN membranes exhibited good long-term and pH stability.

Green Production and Interaction of Carboxylated CNTs/Biogenic ZnO Composite for Antibacterial Activity

Using biomolecule-rich plant extracts, the conversion of metal ions to metal oxide nanoparticles via abiogenic approach is highly intriguing, environmentally friendly, and quick. The inherent inclination of plant extracts function as capping agents in the insitu synthesis. In this study, biogenic zinc oxide nanoparticles (ZnO−NPs) were synthesized using an aqueous leaf extract from Moringaoleifera. The ZnO−NPs were then mixed with carboxylated carbon nanotubes (CNTs) to create a carboxylated CNTs/biogenic ZnO composite using asol–gel method. The CNTs/ZnO composite displayed 18 mm, 16 mm, and 17 mm zones of inhibition (ZOI) against Bacillus cereus, Pseudomonas aeruginosa, and Escherichia coli, respectively. In contrast with ZnO−NPs, the produced carboxylated CNTs/ZnO composite demonstrated a 13 percent elevation in ZOI as antibacterial activity against Bacillus cereus ATCC 19659, Escherichia coli ATCC 25922, and Pseudomonas aeruginosa ATCC 27853. The characterization of ZnO−NPs and the carboxylated CNTs/ZnO composite were performed via FTIR, UV/Vis spectroscopy, SEM, and XRD. The XRD pattern depicted a nano−sized crystalline structure (Wurtzite) of ZnO−NPs and a carboxylated CNTs/ZnO composite. The current work comprehends a valuable green technique for killing pathogenic bacteria, and gives fresh insights into the manufacture of metal oxide composites for future research.

An ultra-thin interlayer bimetallic sulfide for enhancing electrons transport of supercapacitor electrode

Improving the sluggish reaction kinetics and intrinsic inferior electrical conductivity of metal oxides has always been a difficult and important issue. Integration engineering is proposed to effectively solve the above problem, namely, composite modification of metal oxides by materials with high conductivity and high specific surface area. Herein, a nanobelt of bimetallic sulfide/transition metal oxide (CoNiS/MoO3, CSM) composite is designed to improve the electrical conductivity of metal oxides without affecting the morphologic characteristics of materials. Thin-layer CoNiS acts as a channel for electrons and provides a protection for internal metal oxides. And then, in-situ polymerization polyaniline is utilized to strengthen the overall material and improve the specific surface area of the composite material. The CoNiS/MoO3@Polyaniline (CSMP) composites exhibit a considerably high specific capacitance (1884 F g−1 at 1 A g−1) and noticeable cycling capability (92.9 % capacitance retention at 20 A g−1 after 3000 cycles) in three-electrode systems. When CSMP composites are assembled into asymmetric supercapacitor devices, the resultant devices deliver a superior energy density of 86 Wh kg−1 at a power density of 840 W kg−1, admirable cycling stability of 95.6 % and high coulombic efficiency of 99.4 % after 10,000 repeated cycles. In particular, the charge storage mechanism is analyzed in detail based on CV tests, revealing that the surface-controlled capacitive process gradually dominates as scan rate increases. The excellent electrochemical performance well confirms the superiority of the synergistic effects of each component and the elaborate design of the conducting interlayer.

Insights into the highly activity CuMgFe oxides for the selective catalytic reduction of NO by CO: Structure-activity relationships and K/SO2 poisoning mechanism

The selective catalytic reduction of NO by CO is a promising technology for the simultaneous removal of both NO and CO pollution. Hence, a series of CuMgFe composite metal oxides with flower-like morphology was prepared by co-precipitation method for SCR of NO by CO. CuMgFe oxide calcined at 500 °C (CuMgFe-500) exhibited excellent low temperature activity. NO conversion reaches 100% at 225 °C, and it exhibits superior anti-H2O/SO2 ability (250 °C). The excellent activity of CuMgFe-500 was associated with its abundance of surface oxygen vacancies and excellent redox performance. The reaction mechanism of CuMgFe-500 CO catalytic reduction of NO was investigated by in situ DRIFTS. The results show that monodentate nitrate and labile carbonate intermediate species are generated on the catalyst surface. Its reaction follows the E-R mechanism and the L-H mechanism. The introduction of K reduced the surface oxygen adsorption and redox properties of CuMgFe-500 catalyst, which were the main reason for the poor low-temperature activity of K-poisoned catalyst. In situ DRIFTS analysis showed that SO2 hardly inhibits NO adsorption, which were the main reason for the excellent sulfur resistance of CuMgFe-500. This work provides new insights into the development and design of low-temperature CO-SCR catalysts.

Crystallization and pyrolysis of nitric acid pressure leach liquor of limonitic laterite and separation of valuable metals

Based on the advantages of nitric acid pressure process (NAPL) for laterite nickel ores, this study innovatively proposes nitric acid pressure leach liquor crystallization pyrolysis-mixed metal oxides separation process. Firstly, the feasibility and the possible reactions of mixed nitrate pyrolysis were confirmed by thermodynamic analysis. Subsequently, the optimal pyrolysis temperature was experimentally investigated. Then, the pyrolysis process of combined nitrate was thermodynamically analyzed, and the phase composition of mixed metal oxides was determined by X-ray diffraction (XRD), X-ray Photoelectron Spectroscopy (XPS), and Scanning electron microscopy/energy dispersive X-ray spectrometry (SEM/EDS). The Pourbaix diagram shows that using NaOH as leaching agent can selectively separate aluminum from mixed metal oxides, and the variables influencing aluminum's leaching rate are investigated. The experimental results are as follows: the optimal pyrolysis temperature of mixed nitrate crystals is 600 °C; the pyrolysis products are mainly oxides with the formation of NiAl2O4 and MgAl2O4 spinel phases; the aluminum leaching rate is 81.9% under the optimal alkali leaching conditions. The presence of spinel phase is not favorable for aluminum leaching. After leaching, an enriched residue of 15.8% Ni, 1.9% Co and 0.19% Sc was obtained.

Selective syntheses of thick and thin nanosheets based on correlation between thickness and lateral-size distribution

SummaryExfoliation of layered materials, a typical route to obtain 2D materials, is not easily controlled because of the unpredictable downsizing processes. In particular, the thickness control remains as a complex challenge. Here, we found a correlation between the thickness and lateral size distribution of the exfoliated nanosheets, such as transition metal oxides and graphene oxide. The layered composites of the host metal oxides and interlayer organic guests are delaminated into the surface-modified nanosheets in organic dispersion media. The exfoliation behavior varies by combination of the hosts, guests, and dispersion media. Here, we found that the thick and thin nanosheets were obtained on the monodispersed and polydispersed conditions, respectively. The selective syntheses of the thick and thin nanosheets were achieved using a prediction model of the lateral size distribution. The correlation between the thickness and lateral size distribution can be applied to thickness-selective syntheses of 2D materials.

Transport of functional group modified polystyrene nanoplastics in binary metal oxide saturated porous media

Metal oxides exist in porous media in the form of composite metal oxides, which can significantly affect the transport and transformation of pollutants in the soil environment. In this study, binary metal oxide porous media were prepared to explore the effects of solution chemistry, and the presence of binary metal oxides on the transport of functional group modified polystyrene nanoplastics (PSNPs) in saturated porous media. The results show that the existence of binary metal oxides significantly affects the migration ability of PSNPs in saturated porous media. The increase of ionic strength and the presence of multivalent cations affect the transport capacity of PSNPs in porous media. The types of binary metal oxides affect the migration of PSNPs in saturated porous media. The surface roughness and electrostatic interaction are important factors affecting the retention of PSNPs on the surface of binary metal oxide saturated porous media. The surface morphology has a more far-reaching impact. In addition, DLVO theory cannot fully explain the interaction between PSNPs and saturated porous media in the presence of Al3+. This study's results help provide some theoretical support for the migration of microplastics in the soil environment.

Bioactivation of Polyaniline for Biomedical Applications and Metal Oxide Composites

In this work, the oxidative chemical synthesis of polyaniline (PANI) in the presence of glutamic acid (GA) is presented, using ammonium persulfate (APS) as the oxidizing agent. Syntheses were performed by varying the molar ratio of aniline:amino acid:oxidant. The products of the different reactions were characterized by SEM, TEM, and FTIR techniques. It was observed that the molar ratio of aniline:amino acid:oxidant used in the synthesis determines the composition and conformation of the resulting polymer and its morphological and electrochemical properties. Composite hydrogels were prepared by incorporating the drug-loaded PANI nanofibers in situ through polymerization and cross-linking of acrylamide. TEM images of the cross-section of the hydrogel revealed the formation of a three-dimensional system of the polyaniline nanofibers maintained by the insulating matrix of the polyacrylamide hydrogel. The in vitro release of the drug from the hydrogels composed of polyacrylamide/polyaniline against buffer solutions at different pH and temperature was studied, using orbital agitation. Finally, considering the potential of hydrogels composed of polyacrylamide/polyaniline for the controlled release of drugs, a study was conducted to evaluate their cytotoxicity against normal mouse subcutaneous tissue cells.

CuCoO2 Parçacıkları ile Yeni Metal Oksit Kompozitlerin Üretimi ve Kirleticilerin Uzaklaştırılmasında Kullanılması

Elektro-eğirme metodu ile sentezlenen metal oksit nanofiberleri üzerine hidrotermal yöntem ile sentezlenen delafosit parçacıkları ağırlıkça farklı oranlarda dekore edilerek heteroyapılı fotokatalizörler elde edilmiştir. Kalay kaynaklı metal oksitin, bakır kaynaklı delafositin ve oluşturdukları heteroyapılı malzemelerin mikroyapısal, morfolojik, optik ve elektrokimyasal özellikleri karakterize edilmiş ve bu malzemelerin başarılı bir şekilde üretildiği tespit edilmiştir. Ayrıca farklı ağırlık yüzdelerinde delafosit dekore edilen heteroyapıların aktiviteler sistematik olarak incelenmiş, en iyi sonucu veren numunenin Ağ.%0,40 delafosit içeren metal oksit nanofiberi olduğu görülmüştür. Bu fotokatalizör kullanılarak görünür ışık ışıması altında 90 dk’da metilen mavisi (MM) boyasının neredeyse tamamına yakınının (%95,8) bozunduğu tespit edilmiştir. Metal oksit nanofiber fotokatalizörüne kıyasla delafosit dekore edilmiş metal oksit fotokatalizörü MM boyasının bozunma hızında %58,5’lik bir artış sağlamıştır. Fotokatalitik aktivitedeki bu gelişme; metal oksit nanofiberinin dar bant aralığına sahip delafosit parçacıkları ile oluşturduğu heteroyapının daha fazla ışığı soğurumu sayesinde daha fazla e--h+ çifti oluşturması ile ilişkilendirilebilir.

Fabrication and application of Fe2O3-decorated carbon nanotube fibers via instantaneous Joule-heating method

Fe2O3-decorated carbon nanotube fibers (Fe2O3/CNT fibers) exhibit synergistic properties and can be used in flexible electrochemical devices. One of the greatest challenges is to synthesize homogeneous Fe2O3 on CNT fibers. In this paper, we have anchored Fe2O3 nanocrystals compactly and uniformly in CNT fibers via the instantaneous Joule-heating method. By regulating the current intensity, iron catalysts in CNT fibers can be directly converted into Fe2O3 nanocrystals. This method can also prepare Fe2O3 particles of different sizes by adjusting the current value. The distinct structure of Fe2O3/CNT fibers contributed to their excellent electrochemical performance. Because cobaltocene and nickelocene can also be used as catalysts to prepare CNT fibers, this method is expected to be a universal method for the composite of transition metal oxide and CNT fibers.

Synthesis of porous biocarbon supported Ni3S4/CeO2 nanocomposite as high-efficient electrode materials for asymmetric supercapacitors

Biocarbon-supported polymetallic composites (CAS@Ni3S4/CeO2) were fabricated by a facile hydrothermal process. The as-prepared CAS@Ni3S4/CeO2 materials integrated the advantages of transition metal sulfides (good conductivity), rare-earth metal oxides (excellent stability), as well as porous carbon with high surface area, thus exhibiting promising electrochemical performance in supercapacitor applications. Indeed, the optimal CAS@Ni3S4/CeO2-150 composite displayed a high specific capacitance of 1364 F g−1 and impressive cycle performance with capacitance retention of 93.81 % after 10,000 cycles. The calculation of capacitance contribution showed that the satisfying behavior of the electrode was a combination of the diffusion process and the surface capacitance characteristics. Furthermore, the assembled asymmetric supercapacitor (CAS@Ni3S4/CeO2-150//CAS) delivered an ultrahigh energy density of 102.76 Wh kg−1, which was better than that of the commercial activated carbon-based ASC device. This novel strategy might provide a new perspective for transition metal sulfide/rare earth metal oxide composite in the electrochemical energy storage field.

Flower-like metal oxide composite as an efficient sulfur host for stable and high-capacity lithium-sulfur batteries

The major factors of the sulfur host are the high sulfur loading, ability to relieve the volume change, inhibition of the shuttle effect and electric conductivity for lithium-sulfur (Li–S) batteries. To improve the electrochemical performance of Li–S batteries in terms of specific capacity and steady cycling, a significant amount of time and effort has been paid to investigate in the search for new hosts. Because of their capability to prevent the shuttle effect and control the deposition of lithium sulfides, metal oxide materials have been the subject of substantial research and development in relation to their application as sulfur hosts in Li–S batteries. In this study, an advanced type of lithium-sulfur battery called a NiO–ZnO composite was used as a suitable sulfur host (NiO–ZnO/S). A high initial reversible capacity of 1326 mAh g−1 was achieved in NiO–ZnO/S at 0.1C, and the sulfur loading was 73.8 ​wt%. In addition, a great improvement in cycling stability in NiO–ZnO/S (77.6% capacity retention was maintained after 400 cycles at 0.2C) and rate performance (662 mAh g−1 at 5C) were achieved, benefiting from the strategy of anchor function from metal oxide composite (strong adsorption via physical and chemical interactions) and the unique flower-like structure of NiO–ZnO (relief of the volume change).

Investigation on aquathermolysis desulfurization by cutting off C-S bond in thiophene over Fe-Zr-Al catalyst facilitated by surfactants

ABSTRACT This study aimed to apply aquathermolysis technology to remove thiophene sulfur in vacuum residue to obtain qualified petroleum coke products based on a well-designed Fe-Zr-Al catalyst. A coprecipitation method was first developed to synthesize Fe-Zr-Al composite metal oxide catalyst. The thiophene model oil was selected as the reaction system to investigate the process conditions. By adding surfactants into the reaction system to strengthen the mass transfer process of oil–water two-phase, the desulfurization rate of aquathermolysis was improved. It was shown in this study that under the conditions of oil–water ratio of 3:7, temperature of 280°C, pressure of 4 MPa and reaction duration of 60 h, the desulfurization rate could reach 44.39%. The further introduction of 2.4% Sorbitan oleate into the above reaction system could significantly enhance the desulfurization rate to 60.20%. Under the action of Fe2O3 lattice oxygen, thiophene was oxidized and C-S bond was broken, so as to achieve the purpose of desulfurization. The decomposition of water generated active oxygen to continuously replenish lattice oxygen of Fe2O3. The current founding can provide a new way for the effective desulfurization of vacuum residue to produce qualified petroleum coke products.

Biodegradable food packaging and film: a short review

Food packaging plays an important role in maintaining the quality of packaged food from any chemical, physical and environmental damage. Conventionally, plastic material is used in the food industry because of its large availability and excellent mechanical performance at low cost. However, the usage of plastic packaging in huge amounts creates environmental and health issues. The preparation methods of the biodegradable packaging or films have been reviewed. The properties of the packaging are varied depending on the ingredients of the films. The mechanical properties such as tensile strength of the biodegradable films can be improved by additive cellulose fibre or metal oxide composition. Metal oxide composition is added to the production of the film as reinforcement. The increase in metal oxide composition indicates the tendency to increase tensile strength. However, a decrease in elongation at break is observed as the percentage of modified cellulose increases. The addition of a natural bioactive compound such as antioxidant, antimicrobial and water vapour permeability also enhance the functionality of the film and provides intelligent communication with the consumer. The review provided information for readers to choose a suitable preparation method for biodegradable films. The article also offers data on materials selection based on the comparison of the film properties. Biodegradable packaging approach to mitigate the management of plastic waste which serves as an urgent crisis recently and supports in moving towards a sustainable environment.

Fe3O4–CuO@Lignite activated coke activated persulfate advanced treatment of phenolic wastewater from coal chemical industry

In this study, lignite activated coke (LAC) was used as the carrier for the first time, Fe3O4–CuO composite metal oxide was used as the main active material, and the nano-scale magnetic supported composite metal oxide Fe3O4–CuO@LAC catalyst was synthesized for the first time, which can effectively activate the active oxygen in peroxodisulfate (PS). XRD, FTIR, BET, SEM, XPS and other analysis results showed that there was particulate matter with spherical structure on the surface of the active coke, and its diffraction peaks matched well with the characteristic peaks of Fe3O4 and CuO, and it was a mesoporous structure with a specific surface area of 619.090 m2 g−1. By optimizing the experimental conditions, the results showed that more than 92% of hydroquinone can be removed under the conditions of hydroquinone concentration of 50 mg/L, pH = 5, adding 0.1 g/L catalyst and 3 mmol/L PS. EPR and quenching experiments proved that there were four reactive oxygen species in the reaction system ·OH, SO4−·, O2−· and 1O2. According to the degradation products of hydroquinone detected by LC-MS, the possible degradation path was deduced which laid a foundation for solving the problem of difficult treatment of phenol-containing wastewater in coal chemical industry.

Catalytic upgrading of ethanol to higher alcohols over ordered mesoporous Cu-La-Al composite metal oxides

Ordered mesoporous Cu-La-Al composite metal oxides were first synthesized via an evaporation induced self-assembly method and applied in upgrading of ethanol to higher alcohols. The Cu-La-Al composite metal oxide with optimal molar ratio of Cu/La/Al (4/2.6/100) exhibited selectivity and yield to higher alcohols up to 72.2% and 37.7%, respectively. What's more remarkable was that the catalyst exhibited ultra-high stability during 500 h on-stream evaluation. Various characterization techniques including N2 adsorption-desorption, XRD, TEM, TPR, XPS, UV–vis, 27Al NMR, NH3-TPD and CO2-TPD revealed that the synergy of a large amount of octahedrally coordinated Cu2+ and acid-base sites on the surface of Cu-La-Al composite metal oxides was responsible for the excellent catalytic activity and selectivity while the superior stability of the catalyst could be largely attributed to presence of the highly stable CuAl2O4 active phase besides the embedding effect of CuAl2O4 and La2O3 into skeleton of the composite oxides.

Recent Advances of Chlorinated Volatile Organic Compounds' Oxidation Catalyzed by Multiple Catalysts: Reasonable Adjustment of Acidity and Redox Properties.

The severe hazard of chlorinated volatile organic compounds (CVOCs) to human health and the natural environment makes their abatement technology a key topic of global environmental research. Due to the existence of Cl, the byproducts of CVOCs in the catalytic combustion process are complex and toxic, and the possible generation of dioxin becomes a potential risk to the environment. Well-qualified CVOC catalysts should process favorable low-temperature catalytic oxidation ability, excellent selectivity, and good resistance to poisoning, which are governed by the reasonable adjustment of acidity and redox properties. This review overviews the application of different types of multicomponent catalysts, that is, supported noble metal catalysts, transition metal oxide/zeolite catalysts, composite transition metal oxide catalysts, and acid-modified catalysts, for CVOC degradation from the perspective of balance between acidity and redox properties. This review also highlights the synergistic degradation of CVOCs and NOx from the perspective of acidity and redox properties. We expect this work to inspire and guide researchers from both the academic and industrial communities and help pave the way for breakthroughs in fundamental research and industrial applications in this field.

Research Progress of a Composite Metal Oxide Catalyst for VOC Degradation

Volatile organic compounds (VOCs) are atmospheric pollutants that have been of concern for researchers in recent years because they are toxic, difficult to remove, and widely sourced and easily cause damage to the environment and human body. Most scholars use low-temperature plasma biological treatment, catalytic oxidation, adsorption, condensation, and recovery techniques to treat then effectively. Among them, catalytic oxidation technology has the advantages of a high catalytic efficiency, low energy consumption, high safety factor, high treatment efficiency, and less secondary pollution; it is currently widely used for VOC degradation technology. In this paper, the catalytic oxidation technology for the degradation of multiple types of VOCs as well as the development of a single metal oxide catalyst have been briefly introduced. We also focus on the research progress of composite metal oxide catalysts for the removal of VOCs by comparing and analyzing the metal component ratio, preparation method, and types of precursors and the catalysts' influence on the catalytic performance. In addition, the reason for catalyst deactivation and a correlation between the chemical state of the catalyst and the electron distribution are discussed. Development of a composite metal oxide catalyst for the catalytic oxidation of VOCs has been proposed.

The composite of Zr-doped TiO2 and MOF-derived metal oxide for oxidative removal of formaldehyde at the room temperature

Formaldehyde (HCHO) is a common organic pollutant, and it is necessary to prepare an efficient catalyst to degrade it. Metal oxides, especially TiO2, have received widespread attention in the field of HCHO degradation. In this paper, a Zr based MOF UiO-66 was added in the process of Zr doping TiO2 to enhance the ultraviolet light absorption capacity of the catalyst. Then the supported Ag by photoreduction was used to further improve the dispersibility and visible light absorption capacity of the catalyst. When 1000 mg UiO-66 is added, [email protected]–TiO2–1000U6 shows the best degradation rate of 83.4%, and has good stability. Through a series of characterizations, it was found that the ZrO2 nanoparticles derived from UiO-66 were uniformly distributed on the flake TiO2, and the visible light absorption capacity of the catalyst was significantly improved. This work provides a certain reference value for the application of MOF and its derivatives in the field of HCHO degradation.