Ag2O Particles Research Articles

Optimizing Titanium Carbide-Silver Oxide Nanostructures for Targeted Cancer Therapy: Synthesis, Functionalization, and In Vitro Evaluations.

Introduction Cancer remains a significant health challenge, and nanoparticles (NPs) are promising candidates for cancer treatment due to their unique physicochemical properties and ability to selectively target tumour cells. Two-dimensional (2D) nanomaterials, such as MXenes, have attracted interest due to their electronic structures, optical properties, catalytic abilities, and exceptional physicochemical attributes. MXenes are highly suitable for surface functionalization or modification, and their unique properties make them promising candidates for various applications in the biological field. Silver-based compounds have shown remarkable potential in biomedical fields, with silver oxide (Ag₂O) NPs finding applications in various domains. The fabrication of titanium carbide (Ti₃C₂)-Ag₂O heterostructures has been investigated for their anti-cancer properties by conducting cell viability assays on different cell lines. Aim To synthesize and characterize Ti₃C₂-Ag₂O, and to assess its in vitro anti-cancer activity. Materials and methods Ti₃C₂ synthesis begins by dissolving Ti₃AlC₂ powder in a 50% v/v hydrofluoric (HF) acid solution, allowing the aluminium to be etched away. This process should be conducted with continuous stirring for 24 to 48 hours at ambient temperature. Following this, filter the resulting suspension to eliminate aluminium particles and HF, and subsequently wash the Ti₃C₂ MXene with distilled water until a neutral pH is attained. The MXene should then be dispersed in ethanol, and sonication in deionized (DI) water or an alternative solvent should be employed to achieve exfoliation into monolayer or few-layer MXenes. To prepare Ag₂O NPs, dissolve silver nitrate (AgNO₃) in DI water to create a 0.1 M solution, and concurrently prepare a separate 0.1 M sodium hydroxide (NaOH) solution. Introduce the NaOH solution to the AgNO₃ while stirring until a precipitate is observed. The mixture should then be filtered, washed with distilled water, and the NPs dried at 60°C for 12 hours. To fabricate the MXene-Ag₂O composite, disperse the MXene nanoflakes in a solvent through sonication, incorporate the Ag₂O NPs, and stir the mixture for 24 hours. Finally, centrifuge the resultant mixture to isolate the composite, wash it with solvent, and dry it under vacuum conditions. Results The presence of Ag₂O particles on Ti₃C₂ nanosheets was observed, and the high crystallinity of the compound was confirmed through X-ray diffraction (XRD), energy-dispersive spectroscopy (EDS), and scanning electron microscopy (SEM) analyses. These tests verified that the compound was free of impurities and exhibited anti-cancer properties. Conclusion The synthesis of Ti₃C₂ MXenes and Ag₂O NPs was achieved and confirmed through structural characterization methods, including SEM, XRD, and EDS. SEM provided detailed insights into the morphology and distribution of the nanostructures, while XRD and EDS verified their phase purity and elemental composition. Functionalization strategies were employed to enhance the stability and bioactivity of the nanocomposites. In vitro evaluations demonstrated promising anti-cancer activity, indicating that the Ti₃C₂-Ag₂O composites effectively target and inhibit cancer cell growth.

Synthesis and Characterization of Chemically and Green-Synthesized Silver Oxide Particles for Evaluation of Antiviral and Anticancer Activity.

Silver oxide (Ag2O) particles are wonderful candidates due to their unique properties, and their use in a wide range of research, industrial and biomedical applications is rapidly increasing. This makes it fundamental to develop simple, environmentally friendly methods with possible scaling. Herein, sodium borohydride and Datura innoxia leaf extract were applied as chemical and biological stabilizing and reducing agents to develop Ag2O particles. The primary aim was to evaluate the anticancer and antiviral activity of Ag2O particles prepared via two methods. XRD, UV-visible and SEM analyses were used to examine the crystallite structure, optical properties and morphology, respectively. The resulting green-synthesized Ag2O particles exhibited small size, spherically agglomerated shape, and high anticancer and antiviral activities compared to chemically synthesized Ag2O particles. The MTT (3-(4,5-dimethylthiazol-2-yl)-2,5 diphenyltetrazolium-bromide) assay of green-synthesized Ag2O particles showed high anticancer activity against MCF-7 cells with IC50 = 17.908 µg/mL compared to chemically synthesized Ag2O particles with IC50 = 23.856 µg/mL. The antiviral activity of green-synthesized Ag2O particles and chemically synthesized Ag2O particles was also evaluated by a plaque-forming assay, and green-synthesized Ag2O particles showed higher antiviral ability with IC50 = 0.618 µg/mL as compared to chemically synthesized Ag2O particles with IC50 = 6.129 µg/mL. We propose the use of green-synthesized Ag2O particles in cancer treatment and drug delivery.

Synthesis of silver oxide nanoparticles using aqueous leaf extracts of Viscum orientale Willd, Coleus amboinicus Lour and evaluation of their antibacterial activity

The objective of this study was to develop a straightforward biological synthesis of silver oxide nanoparticles (Ag2O NPs) using aqueous leaf extract of Viscum orientale Willd and Coleus amboinicus Lour as a good lowering and capping agent . The UV–visible bands observed at 499 and 451 nm was confirmed the creation of nanosized Ag2O particles making use of Viscum orientale Willd and Coleus amboinicus Lour plants. The formation of Ag2O stretching frequency was confirmed by FTIR spectral studies. Scanning electron microscopy and EDAX analysis displayed Ag2O nanoparticles have been pure and spherical shaped and had been the variety of length from 35±2 nm for (Ag2O NPs) by the usage of Viscum orientale Willd and 32±2 nm for (Ag2O NPs) Coleus amboinicus Lour vice-versa. The fashioned nanoparticles have been cubic in association and face-centered cubic in form, consistent with X-ray diffraction studies. The shaped green kind Ag2O NPs confirmed ambitious antibacterial against each gram possitive and gram negative bacteria.

Facile colorimetric sensor using oxidase-like activity of octahedral Ag2O particles for highly selective detection of Pb(II) in water

Pb(II) is a prevalent heavy metal ion classified as a 2B carcinogen. Excessive intake of Pb(II) in the human body can damage the central nervous system, kidneys, liver, and immune system, leading to permanent brain damage, anemia, and cancer. Colorimetry can be applied to rapidly determine Pb(II) residues, but there are still many challenges in the accuracy and sensitivity of detection. Based on the inhibitory impact of Pb(II) on the oxidase-like activity of octahedral silver oxide (Ag2O), a colorimetric sensor with smartphone-assisted analysis for the Pb(II) detection was first developed. Herein, it has been found that Pb(II) can adsorb onto the surface of octahedral Ag2O, hindering the production of O2− in the reaction system. This ultimately results in the suppression of oxidase-like activity, leading to a lighter purple appearance of the colorimetric reaction solution. The sensor exhibits a high degree of sensitivity and a limit of detection (LOD) for Pb(II) was calculated as 2.2 μg L−1. Hence, the developed colorimetric sensor with high sensitivity, excellent specificity, and high tolerance to sodium ions is hopeful to have practical applications in Pb(II) detection in environmental water samples. Moreover, the sensor will provide a novel strategy for heavy metal ion detection and other substances.

Effect of pH on mussel shells-originated HAP supported Ag catalysts for catalytic combustion of VOCs

Volatile organic compounds (VOCs) triggered serious air pollution and mussel shell caused the marine environmental issues. Herein, hydroxyapatite (HAP) using mussel shells as calcium source was prepared by hydrothermal method with different pH (pH = 6, 8, 10, 11) controls to support Ag catalyst for removal of VOCs. It was found that the amount of skeletal hydroxyl species and textual properties of HAP were controlled by pH effectively, and the increase of hydroxyl groups in the framework resulted in forming smaller-sized Ag2O particles. When pH was 8, the Ag/HAP-BpH=8 catalyst exhibited 100 % conversion of ethyl acetate and toluene at 260 °C and 300 °C, respectively. Silver species were more likely existed on the surface of HAP-BpH=8 to form large-size Ag particles (6.4 nm) and more Ag2O species. The lower ratio of Ag0/Ag+ were crucial for improving the VOCs oxidation activity at lower temperatures. This work applied waste mussel shells to prepare high value-added Ag/hydroxyapatite catalysts and to promote VOCs catalytic oxidation.

Control of microbial agents by functionalization of commercial air filters with metal oxide particles

According to the World Health Organization, low-quality air results in 3.2 million premature annual deaths of which 21 % are attributed to respiratory infections. The recent coronavirus (COVID-19) pandemic, responsible for millions of deaths worldwide, has highlighted the issue of airborne pathogens on human health. Air filtration is an established method to ensure good indoor air quality, being effective at capturing airborne particles and dust, as well as pathogens, and preventing diseases such as asthma. Nevertheless, with usage, water from air humidity, dust, and dirt, including fungi and bacteria spores, can accumulate on filters creating ideal conditions for the propagation of microorganisms. Thus, the filter can become a secondary source for airborne pathogens. In this work, antiviral and antibacterial filters were prepared by spray coating Ag2O, CuO, and ZnO particles into commercially available air filters. The reliability of the filters was tested through particle release in air, through a scanning mobility particle sizer, and filtration performance was measured against an aerosol of iron nanoparticles in nitrogen gas produced through a spark discharge generator. Additionally, the biosafety of the filters was measured in vitro through cytotoxicity tests against L-929 mouse fibroblast cells. Antibacterial activity was measured in vitro against two clinically relevant pathogens: Streptococcus pneumoniae and Pseudomonas aeruginosa and the anti-viral performance was measured against human respiratory syncytial virus. In general, the results have shown that spray coating is a reliable solution, with no detectable cytotoxicity effects or particle release in the air. After functionalization, both Ag2O and CuO compounds have been shown to have total antiviral activity (over 99 %), while only Ag2O presented a clear antibacterial action. In conclusion, spray coating as post-manufacturing functionalization of air filters can be an efficient and low-cost solution against airborne pathogens.

Non-magnetic regenerator material of silver oxide for 4 K cryocoolers

In regenerative cryocoolers, magnetic specific heat is often utilized for heat regeneration at cryogenic temperature, such as below 20 K. Magnetic regenerator materials of rare earth compound which have sufficient specific heat enabled cryocooler to reach below 4 K. However, the magnetic noise emitted from the magnetic materials during the refrigeration cycle affects the performance of noise-sensitive devices. In this study, we propose a non-magnetic regenerator material having “optical phonon degree of freedom” even at cryogenic temperatures, in which silver oxide (Ag2O) is selected. Ag2O decomposes at temperature above 410 K in ambient atmosphere, whereas we succeeded in fabricating a sintered Ag2O bulk and small particles of the size of 0.5 mm with high-density more than 90%. Specific heat measurement down to 100 mK was performed for the sintered bulk sample of Ag2O. Below 10 K, a non-Debye behavior was observed, suggesting the contribution from optical phonon modes. Calculation of the phonon density of state (phDOS) performed by the Evolution Strategy algorithm in addition to the first-principles calculation reveals that phDOS has several distinct peaks at low energies, and the low-energy optical phonons contribute to the non-Debye behavior. The low temperature specific heat of Ag2O enhanced by the optical phonons is larger than conventional non-magnetic regenerator materials when compared in terms of specific heat per volume. Moreover, the calculation of cooling performance of cryocooler using Ag2O particles is found to be reached below 4.2 K. This study shows that non-magnetic material with low temperature specific heat enhanced by optical phonon mode can be used as a regenerator material for regenerative cryocoolers.

Fabrication of a Ag2O/SiO2/Ta2O5 nanocomposite coating for orthopaedic applications: Anticorrosion, photocatalytical and antimicrobial activities

With the considerable growth of the world's elderly population, there is an urgent need to develop bone implants with multifunctional surfaces, including high wear/corrosion resistance, favorable biocompatibility and excellent self-sterilization characteristics. Here, a Ag2O/SiO2/Ta2O5 nanocomposite coating was deposited on a Ti–6Al–4V substrate by double-cathode glow discharge technology. The mechanical characteristics, microstructure, biological corrosion resistance, biocompatibility, visible light catalytic activity and antibacterial properties of the nanocomposite coating were comprehensively evaluated. The Ag2O/SiO2/Ta2O5 coating was composed of crystalline Ta2O5 and Ag2O particles embedded in amorphous SiO2, and showed significantly improved surface hardness relative to the substrate. Further, this coating significantly reduced the corrosion damage from Ringer's solution to the substrate and was conducive to the spreading, adhesion and proliferation of MC3T3-E1 cells. Through investigation of the coating's photocatalytic activity, it was found that the nanocomposite coating solved the limitation that commercial Ta2O5 could not be induced by visible light. Further DFT calculations revealed the orbital occupation of the density of states of the Ag2O/SiO2/Ta2O5 heterojunction and the transfer path of the photogenerated electron-hole pairs. This finding was validated by investigation of antibacterial behaviour under the conditions of dark and visible light. It was shown that the antibacterial rate for the Ag2O/SiO2/Ta2O5 nanocomposite coating against Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus) under visible-light is close to 100%, which is higher than the single antibacterial rate for Ag+ ions under dark conditions. Thus, the multifunctional Ag2O/SiO2/Ta2O5 nanocomposite coating is expected to become an attractive alternative for the surface modification of the next generation of bone implants.

Facile colorimetric smartphone-based biosensor for rapid detection of organophosphorus pesticides residues in environment using the aptamer-enhanced oxidase activity of octahedral Ag2O particles

The long-term and excessive use of organophosphorus pesticides (OPs) leads to hazardous residues in the environment, which threatens human health to a considerable extent. Colorimetric methods can quickly and readily identify pesticide residue, but they still have various challenges in accuracy and stability. Herein, a smartphone-assisted and non-enzymatic colorimetric biosensor was constructed for rapid monitoring of multiple OPs based on the enhanced effect of aptamer on the catalytic ability of octahedral Ag2O. It was demonstrated that the aptamer sequence could enhance the affinity of colloidal Ag2O to chromogenic substrates, and accelerate the generation of oxygen radicals such as superoxide radical (·O2−) and singlet oxygen (1O2) from dissolved oxygen, thereby significantly increasing the oxidase activity of octahedral Ag2O. The color change of the solution can be easily converted to the corresponding RGB values by a smartphone for quantitative and rapid detection of multiple OPs. Hence, the smartphone-based and visual biosensor of multiple OPs was acquired with limit of detection of 10 μg L−1, 28 μg L−1 and 40 μg L−1 for isocarbophos, profenofos and omethoate, respectively. The colorimetric biosensor also exhibited good recoveries in several environmental and biological samples, showing that it may have broad application prospects for detecting OPs residues.

Incorporation of magnesium phosphate into magnesium oxide on Mg[sbnd]Ag alloy through plasma electrolytic oxidation

The application of MgAg alloy for the fabrication of orthopedic implant requires its enhanced corrosion resistance, desired biocompatibility and bactericidal capability without cytotoxicity. Herein, to achieve those purposes, a novel plasma electrolytic oxidation (PEO) treatment was proposed. The PEO coating with a bimodal pore size distribution could form on MgAg alloy surface to enhance its corrosion resistance. Further, the incorporation of magnesium phosphate in the PEO coating may also benefit its biocompatibility. Finally, Ag within the alloy could be gradually oxidized to form incorporated Ag+ and nano-sized Ag2O particles in the coating, which potentially optimize the ionic release kinetics of Ag for a desired antibacterial capability without cytotoxicity. Hence, the present work offers a novel PEO method to improve the corrosion resistance and biological response of MgAg alloy, which enlightens the application of antibacterial Mg alloy in the field of biomedical devices.

A novel colorimetric strategy for rapid detection of dimethoate residue in vegetables based on enhancing oxidase-mimicking catalytic activity of cube-shape Ag2O particles

Although many colorimetric methods have been established for pesticide analysis, most of them rely on inhibiting catalytic activities of natural enzymes or nanozyme, easily leading to false positives in results of pesticide detection. Herein, a simple, stable, and rapid colorimetric method was firstly proposed to detect pesticide residues in vegetables based on enhancing the oxidase-mimicking activity of cube-shape Ag2O. The experiments, including fluorescence probe, electrochemistry, free radical tracking and enzymatic kinetics, confirmed that dimethoate could promote electron transfer from Ag2O to dissolved oxygen and accelerate the release of·O2- radicals as well as 1O2, facilitating the catalytic oxidation of the chromogenic substrate. The colorimetric method exhibited satisfactory sensitivity with the limit of detection as low as 14 μg·L−1. Moreover, such method showed excellent selectivity against other competitive pesticides, and achieved good recovery in several typical vegetables, which indicate that such strategy has a bright application prospect in the field of pesticide detection in food.

Enhanced bacterial inactivation by activated carbon modified with nano-sized silver oxides: Performance and mechanism

In this study, nano-sized silver oxides were loaded on activated carbon (nAg2O/AC) through a facile impregnation-calcination method for enhanced bacterial inactivation from drinking water, in which Escherichia coli (E. coli) was used as target bacteria. XRD and SEM characterization confirmed that nano-sized Ag2O particles (50–200 nm) were successfully prepared and uniformly distributed on the surfaces and pores of AC. Due to the structural reducing groups of AC, surface-bound Ag(I) was partially converted to Ag in the nAg2O matrix and the resulted Ag could sterilize E. coli directly. More importantly, surface-bound Ag could catalyze O2 and H2O to generate reactive oxygen species (ROS) for oxidation sterilization, thus significantly enhanced the inactivation efficiency from 0.8 log10 CFU/mL (nAg2O control) and 0.2 log10 CFU/mL (AC control) to 6.0 log10 CFU/mL in the nAg2O/AC system. The inactivation process was highly pH-dependent, and neutral pH was favorable for sterilization. A sterilization efficiency of 5.2 log10 CFU/mL could still be achieved after 5 running cycles, indicating stable sterilization performance of nAg2O/AC. In addition, the nAg2O/AC also exhibited excellent renewability since a sterilization efficiency of 5.8 log10 CFU/mL was obtained after nAg2O being stripped and reloaded on the AC. These results demonstrated that nAg2O-modified AC is an efficient material for sterilization in water treatment.

Preparation and physico-chemical studies of Ag2O nanoparticles using newly formed malonic acid and ZnCl2-based deep eutectic solvents

Among the many metallic nanoparticles used in biomedical applications, Silver oxide nanoparticles (Ag2O NPs) are the most important and fascinating nanoparticles, and they are particularly relevant in nanomedicine. To prepare Ag NPs, many methods have been employed; we chose the most typical chemical reduction method utilizing a reducing agent. In this investigation, deep eutectic solvents (Malonic acid with Glucose and Fructose, Zinc chloride with Glucose and Fructose) were used as a medium to prepare silver oxide (Ag2O) nanoparticles by the chemical reduction method, and hydrazine hydrate was used as a reducing agent in the presence of sodium hydroxide, a stabilizing agent. The capacity to synthesize a high number of NPs in a short time is one of the most significant advantages of this method. The product silver NPs were characterized using UV–Visible spectroscopy, Fourier-transform infrared spectroscopy (FTIR), Scanning Electron microscopy (SEM), powder X-ray diffraction (XRD) pattern and Energy-Dispersive X-ray Analysis (EDAX). It was observed that Ag2O nanoparticles were formed due to the high viscosity of DESs.The XRD proved that Ag2O nanoparticles were formed in deep eutectic solvents (DESs) of MA-GLU, MA-FRU, ZC-GLU, and ZC-FRU with the grain sizes of the particles -in the nano scale. Furthermore, the SEM analysis also supported that the morphology of the Ag2O particles is very clear at the nano scale and the EDAX analysis supported the purity of the Ag2O nanoparticles obtained in the DESs medium.

Removal of iodide from water using halloysite/Ag2O composites as efficient adsorbent

The efficient removal of iodide (I−) from water is challenging to accomplish because of the large size and low charge of I−. In this study, halloysite/Ag2O composites were prepared, characterized, and used to remove I− from water. The Ag2O nanoparticles primarily resided in the lumen of halloysite in the composites, whose amount and size can be readily controlled by adjusting the concentration of Ag+ during the preparation process. Moreover, there is rapid adsorption of I− by the composites, whose kinetics followed a pseudo-second-order model. With a solid/liquid ratio of 50 mg/20 mL and an initial pH of 7.5 ± 0.2, the maximum I− adsorption capacity of composites with an approximately 0.98% and 2.42% Ag2O content was 13.7 mg/g and 39.99 mg/g, which is 48 and 142 times higher than that of raw halloysite, respectively. Importantly, the composites exhibited high selective adsorption to I−, and their I− removal efficiency is barely affected by the presence of Cl−, Br−, or SO42−. The high adsorption capacity of the composite is driven by the small particle sizes of Ag2O due to the spatial confinement of the lumen of halloysite and the newly formed nanopores between Ag2O particles and the inner wall of halloysite. After capturing the radioactive I−, the composites are expected to constitute a low radiological hazard because of the shielding provided by the halloysite wall. Taken together, these results suggest the halloysite/Ag2O composites could be a promising adsorbent suitable for use in the efficient removal of radioactive I− from nuclear wastewater.

Controlled synthesis of Ag2O/g-C3N4 heterostructures using soft and hard templates for efficient and enhanced visible-light degradation of ciprofloxacin

Pluronic 31R1 surfactant and MCM-41 silica were used to fabricate mesoporous Ag2O/g-C3N4 heterostructures with improved surface areas. The fabricated mesoporous nanocomposite was used to photo oxidize ciprofloxacin. The TEM images of Ag2O/g-C3N4 indicated a uniform dispersion of spherical approximately 4-nm Ag2O nanoparticles on g-C3N4. The mesoporous 0.9% Ag2O@g-C3N4 heterostructure exhibited 100% efficiency in ciprofloxacin oxidation within 60 min when compared with the 25% efficiency in 120 min of pure mesoporous Ag2O and 10% efficiency in 120 min of pure g-C3N4. The highest ciprofloxacin oxidation efficiency achieved was 100%, which was four and ten times better than those of Ag2O and g-C3N4, respectively. This superior performance of the mesoporous Ag2O/g-C3N4 was attributed to the high dispersion of nano-sized mesoporous Ag2O particles on the g-C3N4 surface, narrow bandgap, and significantly high surface areas. The powerful interaction between Ag2O and g-C3N4 ensured robust durability of Ag2O/g-C3N4 heterostructures, which is evident in the fact that five recycling trials of the photocatalyst rendered a minimal loss of efficiency.

Effect of compression pressure on strength of low-temperature sinter bonding produced using silver formate

ABSTRACT Novel pressure-assisted sinter bonding at 200°C using silver (Ag) formate particles was performed in air using an Ag-finished die and substrate to achieve a reliable Ag bondline even at high temperatures. The Ag formate particles, prepared by immersing Ag2O particles for 3 min in a formic acid solution, indicated a pyrolysis reaction near 130°C, forming pure Ag and gases (carbon dioxide and hydrogen). With a paste prepared by mixing the Ag formate particles with α-terpineol, the bonding under 10 MPa exhibited an adequate shear strength of 270 MPa after 3 min. Moreover, a near-full-density structure was observed in the formed bondline after 10 min. Consequently, the compression pressure of 10 MPa resulted in significantly enhanced bondability with reduced void fraction in the formed Ag bondline.

Novel visible-driven Ag2O/Fe2O3/TiO2 nano sized hetero-structured photocatalyst: Synthesis, characterization and photo-degradation of tetracycline

Novel visible light respond Ag2O/Fe2O3/TiO2 nanocomposite was synthesized via impregnation assisted ultrasonic method. This nanocomposite showed impressive photocatalytic properties that can be used to remove the wide range of organic pollutants in order to wastewater treatment. Prepared nano photocatalyst was characterized using FE-SEM, EDX, XRD, DRS and PL analysis. FE-SEM images showed uniform spherical morphology with average particles size less than 16nm. Crystalline phases of synthesized nanocomposite observed through XRD analysis, including anatase, maghemite and Ag2O without any interfering substances. DRS results indicated that absorption spectra extended to visible-light region and effective separation of charge carriers was confirmed by PL spectra. Photocatalytic activity of prepared samples was investigated by tetracycline removal in contaminated water under visible light. The results showed high photo-degradation efficiency under visible light radiation about 90% in 90min. This result is attributed to synergic effect of Fe2O3 and Ag2O. Fe2O3 leads to narrow the band gap and decrease the charge carriers’ recombination, additionally, presence of Ag2O particles acts as a photosensitive component and formation of Ag-Ag2O structure causes the self-stability of photocatalyst.

Silver-Modified Nano Mordenite for Carbonylation of Dimethyl Ether

Mordenite (H-MOR) catalysts were synthesized by a hydrothermal method, and silver-modified mordenite (Ag-MOR) catalysts were prepared by ion exchange with AgNO3 at different concentrations. The performance of these catalysts in the carbonylation of dimethyl ether (DME) to methyl acetate (MA) was also evaluated. The catalysts were characterized by Ar adsorption/desorption, XRD, ICP-AES, SEM, HRTEM, 27Al NMR, H2-TPR, NH3-TPD, Py-IR, and CO-TPD. According to the characterization results, Ag ion exchange sites were mainly located in the 8-membered ring (8-MR) channels of Ag-MOR; evenly dispersed Ag2O particles were also present. The acid site distribution was changed by the modification of Ag, and the amount of Brønsted acid sites increased in 8-MR and decreased in 12-MR. The CO adsorption performance of the catalyst significantly increased with the modification of Ag. These changes improved the conversion and selectivity of the carbonylation of DME. Over 4Ag-MOR in particular, DME conversion and MA selectivity reached 94% and 100%, respectively.

Synthesis of Ag2O Coated TiO2 Nanoparticles by Sonochemically Activated Methods for Enhanced Photocatalytic Activities

TiO2 nanoparticles were successfully synthesized by sol-hydrothermal (SH) method using sonochemically activated precursors. Sonochemical activation yields product bearing desirable crystallinity at relatively lower temperature in comparison with conventional SH method. Glycine was used as a mineralizer in the ultrasound activation process which suppress the formation of brookite phase (of TiO2) observed in the sonochemically activated sample. TiO2 sample synthesized in presence of Glycine [SA-SH(GLY)] was further modified by coating Ag2O nanoparticles by sonochemical (SD-Ag) and photochemical (PD–Ag) methods. The deposition by sonochemical method yields product with better crystallinity, high surface area and improved optical properties. Morphological investigations confirm the formation of rounded cube and cube shaped Ag2O particles in the sonochemical and photochemical methods respectively. Photoactivities of the catalysts were investigated in terms of degradation of methyl orange (MO) dye contaminated aquatic waste. Equilibrium of MO photo-degradation was achieved within about 90 min with removal efficiencies of 99.9, 67.1, and 44.4% for SD-Ag, PD–Ag, and SA-SH-(GLY) samples, respectively at 50 mg/L of MO dye concentration. The high photo-catalytic activity of SD-Ag sample was observed for MO photo-degradation, which is attributed to the improved properties like crystallinity, visible light absorption capacity and higher surface area. Advance route of sonochemical activation process for synthesis of Ag2O co-capped TiO2 nanocomplex for MO photo-degradation

Visible light driven photooxidation of imazapyr herbicide over highly efficient mesoporous Ag/Ag2O–TiO2 p-n heterojunction photocatalysts

This work explores the photoefficiency of mesoporous TiO2 photocatalysts modified with Ag0 and Ag2O in the photooxidation of imazapyr herbicide using visible light radiation. Ag/Ag2O–TiO2 photocatalysts with a variable Ag content (0.5–2.0 wt%) were synthesized through a sol-gel process. Their physicochemical properties were investigated by different techniques: N2 physisorption, XRD, HRTEM, FTIR, DRS UV–Vis, Raman, XPS, PL and photocurrent measurements. XRD and XPS showed the existence of both Ag2O and metallic Ag on TiO2 surfaces. UV–Vis spectra obtained for all Ag/Ag2O–TiO2 samples showed a shift in the absorption edge to the visible region and a decrease in the band gap energy (Eg) with respect to the pure TiO2. Photocatalysts with 1.5% and 2 wt % Ag loading showed total imazapyr destruction within 180 min upon visible light illumination. Both photocatalysts were found to degrade imazapyr herbicide 20.5 fold and 12.5 fold faster than the parent TiO2 and commercial Degussa P25, respectively. The high photoefficiency of the optimized Ag/Ag2O–TiO2 photocatalysts is explained by the combined effect of the presence of mesoporous anatase in the TiO2 matrix, creation of a p-n junction amongst the Ag2O nanoparticles and mesoporous TiO2 matrix, a low Eg and low recombination between photoinduced electrons and holes derived from the Ag2O–TiO2 p-n heterojunctions, and the presence of metallic Ag in the Ag2O particles, which promotes electron transfer in the p-n heterojunction.