Sonochemistry fabrication of Er2Sn2O7 nanoparticles with advanced photocatalytic performance of their carbonic nanocomposites

The insufficiency of clean water sources has become a perilous tension for the future of the world that one of the eco-friendly and cost-effective solutions is the photocatalytic process for removal of artificial dyes and poisonous organic impurities. In the current research, a simple sonochemistry process was accomplished to gain Er₂Sn₂O₇ (ESO) nanoparticles with progressive photo-catalytic proficiency. Various surfactants of cationic Cetyl Trimethyl Ammonium Bromide (CTAB), anionic Sodium dodecyl sulfate (SDS) and polymeric polyethylene glycol 6000 (PEG 6000) were utilized to the creation of pure Er₂Sn₂O₇ nanoparticles. The figure and dimension of products were studied by various characterization procedures of spectroscopic and microscopic. The photo-degradation performances of the pure Er₂Sn₂O₇ nanoparticles prepared in different conditions were tested to remove of diverse synthetic dyes. Carbon-based nanocomposites of graphitic carbon nitrides (g-C₃N₄), graphene quantum dots (GQDs) and graphene oxide (GO) present enhanced photocatalytic activities. The outcome of the catalyst size, type of dye, kind of carbon structure and scavenger kind was labeled on modifying ability of Er–Sn–O nano-catalyst task. Optimized Er₂Sn₂O₇/g-C₃N₄ nanocomposites have an efficiency of 93.9% for degradation of acid red dye that OH radicals support photo-degradation of contamination.     

Enhanced photocatalytic activity of Sr7Mn7O19.62-Dy2O3 nanocomposite synthesized via a green method

The removal of pollutants existing in industrial wastewater is one of the worldwide main challenging issues owing to the increasing demands for clean water supplies. The purpose of this study is to investigate the feasibility of new synthesized Sr₇Mn₇O_19.62-Dy₂O₃ nanocomposites for the removal of organic dyes through photo-degradation mechanism from the wastewater. In this regard, for the first time, Sr₇Mn₇O_19.62-Dy₂O₃ nanocomposites synthesized by the sol-gel combustion method using the different green capping agents and final product characterized via X-ray powder diffraction (XRD), Fourier-transformed infrared spectroscopy (FT-IR), Scanning electron microscopy (SEM), Transmission electron microscopy (TEM), Energy-dispersive X-ray spectroscopy (EDS), vibrating sample magnetometer (VSM), and Ultraviolet (UV)-visible spectroscopy. Furthermore, the photocatalytic activity Sr₇Mn₇O_19.62-Dy₂O₃ nanocomposite investigated in the presence of various parameters such as dye type, the effect of pH, and different values of the green capping agents. The results showed that the best photocatalytic activity and hence the removal of pollutants for the proposed nanocomposite (bandgap ?3.25 eV) achieved using Ficus Carica as green capping agent and calcination temperature of 900 °C in the presence of Eriochorme black T dye (photo-degradation of %94.52). This study conclusively shows the potential regarding the development of Sr₇Mn₇O_19.62-Dy₂O₃ as a novel and effective nanocomposite for wastewater treatment.     

Gd3Fe5O12/MgAl-LDH nanocomposites: Sonochemical synthesis,optimization and electrochemical hydrogen storage studies

The development of an eco-friendly and pollution-free hydrogen storage cell power system has received considerable research attention in recent years. Several prominent developments in energy storage mechanisms have been made during the last decade, influencing innovation, exploration, and the probable path for improving energy storage knowledge. We propose a hydrogen energy storage system based on novel electrode materials and electrochemical methods. A series of nanocomposites based on MgAl-LDH and Gd₃Fe₅O₁₂ garnet were designed as active materials. Ultrasonic radiation was used for the synthesis of Gd₃Fe₅O₁₂/MgAl-LDH nanocomposites. Structures of Gd₃Fe₅O₁₂ without any impurities were achieved by sonication power of 90 W/cm² while the synthetic sample without sonication power led to the synthesis of Gd₃Fe₅O₁₂ in the presence of GdFeO₃ phase. The hydrogen storage capacity for pristine MgAl-LDH and Gd₃Fe₅O₁₂ was measured at 213 and 388 mAhg⁻¹ after 15 cycles, respectively. Then, capacity for Gd₃Fe₅O₁₂/MgAl-LDH nanocomposites increased to 316 mAhg⁻¹ at current of 1 mA in 15th cycles. Newly developed electrode materials such as Gd₃Fe₅O₁₂/MgAl-LDH with mechanisms such as spillover, redox and physical adsorption are excellent candidates for energy storage power systems.     

Li2MnO3/LiMnBO3/MnFe2O4 ternary nanocomposites: Pechini synthesis,characterization and photocatalytic performance

Li₂MnO₃/LiMnBO₃/MnFe₂O₄ ternary nanocomposites were synthesized via modified pechini sol-gel approach employing the mixture of metal cations, boric acid, ethylene glycol and ethylene diamine tetra acetic acid gelating agent. Shape and size of nanocomposites was controlled by changing molar ratio of metal ions, ethylene glycol and gelating agent. In order to confirmation of crystalline and structural features of products, analyses of X-ray diffraction, Fourier transform infrared and energy dispersive X-ray were carried out. Scanning electron microscopy and transmission electron microscopy images were taken for morphology investigation of nanostructure products. Band-gap of ternary nanocomposites calculated by UV–Vis data is 2.6 eV. Magnetic property of Li₂MnO₃/LiMnBO₃/MnFe₂O₄ ternary nanocomposites investigated through vibrating sample magnetometer presents ferromagnetic behavior. Moreover, photocatalytic activity of Li₂MnO₃/LiMnBO₃/MnFe₂O₄ and Li₂MnO₃/LiMnBO₃ nanocomposites was investigated in aqueous solution via UV and visible light for degradation acid red 88 dye. Some effective parameters such as dye concentration, irradiation and nanocomposite type were evaluated for optimum removal of water pollutant dye.     

Improvement of electrochemical behavior of Sn2Fe/C nanocomposite anode with Al2O3 addition for lithium-ion batteries

Sn₂Fe/Al₂O₃/C nanocomposites are synthesized using a high-energy, mechanical milling method with thermally synthesized Sn₂Fe, Al₂O₃ and carbon (Super P) powders. The effect of Al₂O₃ addition on the microstructure of the Sn₂Fe/Al₂O₃/C nanocomposites is examined. The electrochemical characteristics of the material as an anode in lithium-ion batteries are also evaluated. High-resolution transmission electron microscopy shows that the crystallite size of active Sn₂Fe in the Sn₂Fe/Al₂O₃/C nanocomposite is smaller than that of the Sn₂Fe/C nanocomposite without Al₂O₃. A decrease in the initial irreversible capacity and enhanced cycle performance of the Sn₂Fe/Al₂O₃/C nanocomposite electrode are observed.     

Green synthesis of DyBa2Fe3O7.988/DyFeO3 nanocomposites using almond extract with dual eco-friendly applications: Photocatalytic and antibacterial activities

For the first time, photocatalytical and antibacterial activities of DyBa₂Fe₃O_7.988/DyFeO₃ (Dy-Ba-Fe-O) nanocomposites as eco-friendly applications of this compound was studied in the same time. Since the applications of this compound are eco-friendly, ultrasound technique was chosen as the synthesis method. Achieving the pure product with good crystallinity with the lowest energy consumption can be considered as one of the advantages of this work. Using the almond core extract as a natural reagent was another reason for consideration this method as a green process. Band gap of this nanocomposite was estimated about 2.6 eV that showed this product can be used as a visible-active photocatalyst. Rhodamin-B dye as an organic pollutant model using the as-prepared nanocomposite was degraded about 72% that was a considerable result under visible irradiation. Elimination of microorganisms was studied by disc diffusion to recognize the sensitivity of bacterial (Staphylococcus aureus, Bacillus subtilis, E. coli, K. pneumonia and P. aeruginosa) strains the manufactured. The results confirmed that DyBa₂Fe₃O_7.988/DyFeO₃ (DBFeO) nanocomposites can be used as an antibacterial agent because of the manifested strong antibacterial ability upon Gram-negative pathogens such as K. pneumonia and E. coli. The properties of this product were characterized by different analyses including SEM, XRD, EDS, FT-IR, DRS and TEM.     

CuFe2O4/SnO2 nanocomposites as anodes for Li-ion batteries

Ultrafine powders of nanocrystalline CuFe₂O₄ and CuFe₂O₄/10 wt.% SnO₂ nanocomposites are prepared by a urea–nitrate combustion method. Phase pure and highly crystalline CuFe₂O₄ (tetragonal structure) and CuFe₂O₄/SnO₂ (cubic structure) are obtained after sintering at 1100 °C. The average particle size is 10–20 and 20–30 nm, respectively. Both the nanoferrite anodes have an excellent specific capacity of greater than 800 mAh g⁻¹ versus Li metal. It is concluded that SnO₂ doping improves the coulombic efficiency of copper ferrite anodes from 65 to 99.5% via an enhanced structural stability.     

SnO2 nanoparticles@polypyrrole nanowires composite as anode materials for rechargeable lithium-ion batteries

The SnO₂@polypyrrole (PPy) nanocomposites have been synthesized by a one-pot oxidative chemical polymerization method. The structure, composition, and morphology of the as-prepared SnO₂@PPy nanocomposites are characterized by XRD, FTIR, TG, SEM, and TEM. Electrochemical investigations show that the obtained SnO₂@PPy nanocomposites exhibit high discharge/charge capacities and favorable cycling when they are employed as anode materials for rechargeable lithium-ion batteries. For the SnO₂@PPy nanocomposite with 79 wt% SnO₂, the electrode reaction kinetics is demonstrated to be controlled by the diffusion of Li⁺ ions in the nanocomposite. The calculated diffusion coefficiency of lithium ions in the SnO₂@PPy nanocomposite with 79 wt% SnO₂ is 6.7 × 10⁻⁸ cm² s⁻¹, while the lithium-alloying activation energy at 0.5 V is 47.3 kJ mol⁻¹, which is obviously lower than that for the bare SnO₂. The enhanced electrode performance with the SnO₂@PPy nanocomposite is proposed to derive from the advantageous nanostructures that allow better structural flexibility, shorter diffusion length, and easier interaction with lithium.     

Synthesis and characterization of MWCNT impregnated with different loadings of SnO2 nanoparticles for hydrogen storage applications

Multi-walled carbon nanotubes (MWCNTs) loaded with different wt % of tin oxide (MWCNT: SnO₂) nanocomposites have been synthesized by impregnation method and their hydrogen uptake capacity is investigated. The hydrogen storage capacity of MWCNT: SnO₂ (3 wt %), MWCNT: SnO₂ (5 wt %), MWCNT: SnO₂ (7 wt %) and MWCNT: SnO₂ (9 wt %) composites is found to be 2.03, 1.95, 0.94 and 1.59 wt % respectively. The enhanced hydrogen storage capacity is due to SnOC bond formation and summative adsorption of hydrogen by MWCNT and SnO₂ nanoparticles. Moreover, physical/chemical properties of composites are examined by Fourier transform infrared spectroscopy, scanning electron microscopy, energy dispersive X-ray spectroscopy, and X-ray diffraction, thermogravimetric and Raman analyses. Hydrogen adsorption and desorption behavior of the composites are analyzed using Raman and thermogravimetric analyses. The stored hydrogen is desorbed in the temperature range of 183 ?C-536 °C.     

Hetero intimate interface CN/Fe–SnO2 micro flowers towards superior photocatalytic applications

In this report, novel Fe doped SnO₂/g-C₃N₄ hetero intimate interface (CN/Fe–SnO₂) micro flowers were prepared successfully using the optimized amounts of g-C₃N₄ and Fe–SnO₂ as precursor material and DMSO-DD water (1:10) mixture exploit as a solvent by the conventional hydrothermal way. The physiochemical features of developed nanomaterials were characterized by various analytical methods. It was found that the crystalline structure of SnO₂ was maintained even after doping of iron, as disclosed by XRD, and also signifies the distortion of g-C₃N₄ after the hydrothermal method. According to XRD results, the crystal system of pure SnO₂ proved as tetragonal. Instead of small ionic radius Sn⁴⁺, high ionic radius Fe²⁺ was substituted, the volume of the unit cell was slightly developed and the XRD pattern also becomes wide because of the strain impact. From FESEM and HRTEM results, we can observe flower-like g-C₃N₄ nanosheets tightly sandwiched with Fe doped SnO₂ (CN/Fe–SnO₂). Morphology plays a crucial role because its layered structure provides more active sites and light-harvesting capability due to multiple internal reflections and interface charge separations. Moreover, the Fe doping overhauls the energy band structure and affords the Z-scheme electron conduction mechanism of CN/Fe–SnO₂ heterojunction. The prepared CN/Fe–SnO₂ micro flowers are more desirable for application in photocatalytic water splitting hydrogen production and Methylene blue (MB) dye degradation, through this nanocomposite we have achieved 933μmole/2 h hydrogen production and 97% of Methylene blue (MB) dye degradation.     

Effect of Sm substitution for Gd on the electrical conductivity of fluorite-type Gd2Zr2O7

Gd_2−xSm_xZr₂O₇ (x = 0, 0.2, 0.6, 1.0, 1.4, 1.8, 2.0) ceramic powders synthesized with the chemical-coprecipitation and calcination method were pressureless-sintered at 1873 K for 10 h in air. The electrical conductivity of Gd_2−xSm_xZr₂O₇ ceramics was investigated by complex impedance spectroscopy over a frequency range of 0.01 Hz to 15 MHz. Gd_2−xSm_xZr₂O₇ is an oxide-ion conductor in the oxygen partial pressure range from 1.0 × 10⁻¹⁵ to 1.0 atm and in the temperature range of 623–873 K. The measured electrical conductivity obeys the Arrhenius relation. The activation energy and pre-exponential factor for grain-interior conductivity gradually decrease with increasing Sm content. The grain-interior conductivity varies with the Sm substitution for Gd, and reaches the maximum at the equal molar of Sm³⁺ and Gd³⁺ in Gd_2−xSm_xZr₂O₇ ceramics. A significant increase in the grain-interior conductivity is obtained by isovalent rare-earth element like Sm substitution for Gd in the temperature range of 623–873 K.     

Solar photocatalytic degradation of a reactive azo dye in TiO2-suspension

The photocatalytic decolourisation and degradation of an azo dye reactive orange 4 (RO4) in aqueous solution with TiO₂-P25 (Degussa) as photocatalyst in slurry form have been investigated using solarlight. There is a significant difference in adsorption of dye on TiO₂ surface with the change in solution pH. The effect of various photocatalysts such as TiO₂-P25, TiO₂ (anatase), ZnO, CdS, Fe₂O₃, SnO₂ on the decolourisation and degradation has been studied. The order of reactivity of photocatalysts is TiO₂-P25>ZnO>TiO₂ (anatase). CdS, Fe₂O₃ and SnO₂ have negligible activity on RO4 decolourisation and degradation. The effects of various parameters such as catalyst loading, pH and initial concentration of the dye on decolourisation and degradation have been determined. The degradation was strongly enhanced in the presence of electron acceptors such as H₂O₂, (NH₄)₂S₂O₈ and KBrO₃. The effects of dye-assisting chemicals such as Na₂CO₃, NaCl have been carried out. Addition of these chemicals inhibits the removal rate. The photodecolourisation and degradation kinetics are discussed in terms of Langmuir–Hinshelwood kinetic model.     

Efficient sensitization of nanocrystalline TiO2 films with cyanine and merocyanine organic dyes

Various kinds of cyanine and merocyanine organic dyes having short anchoring groups as sensitizers on nanocrystalline TiO₂ electrodes were investigated to promote the short-circuit photocurrent (J_sc) and the solar light-to-power conversion efficiency (η_sun). The J_sc and η_sun improved when the three different three dyes (yellow and red cyanine dyes, and blue squarylium cyanine dye) were adsorbed simultaneously on a TiO₂ electrode, as compared with the J_sc and η_sun of the TiO₂ electrodes adsorbed by each single dye. The maximum η_sun was 3.1% (AM-1.5, 100 mW/cm²). The J_sc and η_sun were influenced by the solvents for the dye adsorption on the TiO₂ electrode, and the efficiencies were improved by the addition of some cholic acids into the dye solution for adsorption. The electron transfer and/or the energy transfer from the red cyanine dye to the blue cyanine dye was observed on a SiO₂ film using emission spectroscopy, suggesting a strong interaction between two dyes. The J-like aggregates of the blue cyanine dyes hardly showed sensitization efficiency.     

SnO2 promoted carrier separation in superior thin g-C3N4 nanosheets for enhanced photocatalytic degradation and H2 generation

The construction of heterostructures is an efficient approach to improve the photocatalystic performance of semiconductors. In this paper, SnO₂-g-C₃N₄ (SnO₂–CN) nanocomposites were created via thermal polymerization using SnO₂ nanoparticles and layered g-C₃N₄ nanosheets. A mechano-chemical pre-reaction and the second thermal polymerization of bulk g-C₃N₄ play important roles for the formation of SnO₂/g-C₃N₄ heterostructures with improved interface nature. The heterostructures with an optimized SnO₂ weight ratio of 10% was obtained by adjusting parameters for enhanced photocatalytic reactions in visible light region. Hydrogen generation and the degradation of rhodamine B (Rh B) were tested to characterize the photocatalytic performance of the SnO₂–CN nanocomposites. The degradation of a 20 mg/L Rh B solution was finished within 15 min, in which the degradation rate was about twice compared with superior thin g-C₃N₄ nanosheets prepared by a two-step polymerization procedure. The SnO₂–CN nanocomposite with 10% SnO₂ revealed a H₂ generation rate of 2569.5 μmol g⁻¹L⁻¹. The enhanced photocatalytic performance is ascribed to a type II heterostructure formed and improved interface properties between g-C₃N₄ and SnO₂. In addition, the improved conductivity of SnO₂ promoted the photogenerated carrier separation and transfer. The result provided a new idea for the construction of g-C₃N₄ heterostructures with improved interface characterization and the improvement of photocatalytic properties.     

Synthesis of carbon coated Fe3O4/SnO2 composite beads and their application as anodes for lithium ion batteries

Abstract

Two metal oxide materials, namely, Fe₃O₄ and SnO₂, were combined into one specially designed nanostructure for lithium ion battery application. Hollow and porous Fe₃O₄ beads with an average size of ～700 nm were first synthesised through a one-step solvothermal route, followed by the decoration of SnO₂ nanoparticles via a hydrothermal method. A thin carbon layer was coated to further enhance the overall electrochemical performances. Under the current density of 100 mA g^?1, the first reversible capacity of such composite beads reached 834·7 mA h g^?1. While being tested at a higher current density of 500 mA g^?1, carbon coated Fe₃O₄/SnO₂ delivered steady reversible capacities with 569·5 mA h g^?1 at two hundredth cycle. Such performances were attributed to the high theoretical capacities of the metal oxides, desired morphology in nanoscale, carbon coating layer and the synergistic effect between Fe₃O₄ and SnO₂.     

Sol-gel auto-combustion synthesis of a novel chitosan/Ho2Ti2O7 nanocomposite and its characterization for photocatalytic degradation of organic pollutant in wastewater under visible illumination

In the last few years, the release of toxic contaminants into the ecosystem has expanded dramatically. Hence, multiple photocatalysts have been improved for the elimination of toxic contamination. The manufacture of photocatalysts based on nanostructures is a promising strategy to improve photocatalytic potential. In this regard, Ho₂Ti₂O₇ and chitosan-coated Ho₂Ti₂O₇ nanocomposites have been manufactured through a facile auto-combustion and co-precipitation route. Diverse factors, including calcination temperature, type of precursor of titanium, solvent, and types of fuels, can affect the structure, purity, morphology, and particle size of samples. Ho₂Ti₂O₇ nanostructures are a good candidate for photocatalytic evolution owing to their adequate bandgap (2.5 eV) in the visible region. This is the first study of the photocatalytic efficacy of Ho₂Ti₂O₇ and chitosan-coated Ho₂Ti₂O₇ nanocomposites. Their photocatalytic performance was explored over several dyes as pollutants, including malachite green, methyl violet, eriochrome black T, methylene blue, acid red 198, methyl orange, and thymol blue under visible radiation. Besides, diverse parameters, such as Ho₂Ti₂O₇ contents, dye levels, were studied on the efficiency of the reaction. The results demonstrated that the maximum efficiency of Ho₂Ti₂O₇ and its chitosan-coated was perceived over malachite green with degradation percentages of 95.7 and 79.9%, respectively. Ho₂Ti₂O₇ nanostructures were highly stable due to their recyclability test and kept their photocatalytic potential over five cycles. The decrease in photocatalytic efficiency in the 5th period is 7.1%.     

Hydrogen-based sono-hybrid catalytic degradation and mitigation of industrially-originated dye-based pollutants

Hazardous pollutants in water bodies have increased global concern due to their considerable toxicity and threat to the environmental matrices. Conventional remediation approaches are futile for eliminating various toxic dyes and other related pollutants. Regulations compliances for wastewater expulsion have forced scientists to either introduce new methods or upgrade present technologies to attain operative deprivation and mineralization of pollutants. Advanced oxidation processes (AOPs) relying on the generation of highly reactive oxidizing radicals, like ^?O, and ^?OH are considered efficient to attain high mineralization of a large number of dye pollutants and many other organic contaminants. Compared to conventional AOPs, including photocatalysis, Fenton, photo-ferrioxalate, ozone/UV, ozonation, H₂O₂/UV, etc., sonolysis is a comparatively newer AOP that implicates the use of ultrasound irradiation for generating oxidizing radicals, leading to the degradation of recalcitrant dyes. Due to no chemical catalyst requirement and being executed at ambient pressure and temperature, ultrasound-assisted AOPs have become robust hybrid AOPs to degrade environmental contaminants. Ultrasound treatments to mitigate pollutants are important because of the cavitation phenomenon. This review focuses on the degradation of dyes through ultrasound-based advanced oxidation processes. Firstly, we have described the ecotoxicity and health hazards of dye pollutants, then different sono-based methods such as sono-hybrid Fenton (US + Fe⁺²/H₂O₂), Fenton like (Fe⁺³/H₂O₂) process, sono-hybrid photo-Fenton process (US + Fe²⁺/H₂O₂/UV system, sono-hybrid hydrogen peroxide (US + H₂O₂), sono-hybrid catalytic (photo/electro) processes have been examined in details for their efficacy for degradation of dyes in wastewater. Future perspectives of ultrasound-assisted AOPs for dyes removal have also been discussed.     

An excellent H2 production photoelectrode based on mixed valence Sn3O4 nanoflake arrays treated by H2O2 hydrothermal reaction

To design nanostructured photoelectrodes with unique morphology and suitable band structure is a crucial step for potential photoelectrochemical application. For above purpose, the compact Sn₃O₄ nanoflakes with the smooth surface have been directly grown on carbon paper substrate by a simple hydrothermal method. It is found that the molar ratio of Sn²⁺ and Sn⁴⁺ ions in Sn₃O₄ nanoflakes can be modulated by the subsequent H₂O₂-assisted hydrothermal treatment. The effect of different molar ratio on the energy band has been investigated systematically, together with the evolution of the surface morphology of nanoflakes. Finally, a highly efficient photoelectrode based on Sn₃O₄ nanoflake has been prepared by the H₂O₂-assisted hydrothermal process, which is of larger active surface area and suitable band structure, and therefore exhibits the excellent photocurrent response and photocatalytic performance for H₂ production. The photoelectrode based on Sn₃O₄ nanoflake displays enhanced photocurrent with 40 μA cm^?1 at a basis of 0 V and higher H₂ generation rate with 1.43 × 10⁴ μmol h^?1 g^?1, much better than those of the original sample. Such superior performance can be probably attributed to the combined effect of unique porous nanoflake-structured, higher active surface area and suitable band structure.     

Inducing a deep impurity level in Li2SnO3 by ionic Bi–O bonding to enhance light absorption in photocatalysis

Orbital engineering is an important strategy for modulating light absorption in photocatalysis. Here, Bi doping of the oxide photocatalyst Li₂SnO₃ to enhance light absorption was rationally designed by orbital engineering. Based on density functional theory, owing to the lower Bi 6s energy level compared with that of Sn 5s, a deep impurity energy level induced by ionic Bi–O bonds is generated in the middle band gap of Li₂SnO₃. The impurity energy level can facilitate the utilization efficiency of light absorption, leading to remarkably enhanced photocatalytic performance. For Li₂Sn_0.9Bi_0.1O₃, the photodegradation rate of tetracycline solution reached 76% within 30 min, which was approximately 2.6 times higher than that for Li₂SnO₃. A radical trapping experiment revealed that the holes (h⁺) play a dominant role in the elimination reaction. Finally, liquid chromatography–mass spectrometry was performed to monitor the photocatalytic process. This study lays a foundation for rational design of photocatalysts with excellent light absorption for photocatalysis.