Facile synthesis of Ag/AgX (X = Cl, Br) with enhanced visible-light-induced photocatalytic activity by ultrasonic spray pyrolysis method

Photocatalytic degradation of 2,4-dichlorophenol using nanomaterials silver halide catalysts

In this study, the photocatalytic activity of nanomaterials Ag/AgX (X = Cl, Br, I) is reported. Highly efficient silver halide (Ag/AgX where X = Cl, Br, I) photocatalysts were synthesized through a hydrothermal method. The samples were characterized using a range of techniques such as X-ray diffraction (XRD), scanning electron microscopy (SEM), and Brunauer-Emmett-Teller (BET) to check their structural, morphology, textural and optical properties. In addition, the photocatalytic activity of photocatalysts was evaluated through the degradation of 2,4-dichlorophenol (2,4-DCP) under UV and visible light irradiation. XRD analysis confirmed the presence of a single-phase structure (pure phase) in the synthesized photocatalysts. SEM micrographs showed agglomeration with a non-uniform distribution of particles, which is a characteristic of surfactant-free precipitation reactions in aqueous media. The Ag/AgBr photocatalyst exhibited the best degradation efficiency, resulting in 83.37% and 89.39% photodegradation after 5 h of UV and visible light irradiation, respectively. The effect of catalyst loading, initial solution pH, and 2,4-DCP concentration was investigated for the best-performing Ag/AgBr photocatalyst. The degradation kinetics were best described by the pseudo-first-order Langmuir-Hinshelwood model. The photocatalytic capacity of Ag/AgBr decreased by 50% after five reuse cycles. SEM images revealed heightened levels of photodegradation on the catalyst surface. The study proved the feasibility of using simple synthesis methods to produce visible light active photocatalysts capable of degrading refractory phenolic pollutants in aqueous systems.

Calcium alginate gels-functionalized polyurethane foam decorated with silver nanoparticles as an antibacterial agent for point-of-use water disinfection

This paper reports the preparation of calcium alginate gels-functionalized PUF decorated with AgNPs (CA/PUF@Ag) by in situ reduction of Ag⁺ ions to form AgNPs with weakly reducing glycerol in CA/PUF composite. The water-adsorbing capacity, chemical structure, crystalline nature, elemental composition and morphologies of the composite were characterized. The Ag release behavior of CA/PUF@Ag was investigated. The inhibition zone test, time-dependent co-culture assay, test tube test, and antibacterial filtration experiment with Escherichia coli as an indicator of bacterial contamination were conducted to explore the antimicrobial efficacy. Results indicated that the CA/PUF@Ag prepared at 0.25 % w/v of SA could absorb more water with a higher swelling ratio of 8.0 g/g than that of PUF@Ag (6.0 g/g), which was subsequently squeezed by minimal pressure stimuli. The CA/PUF@Ag had a larger initial AgNPs loading amount (8.48 mg/g), lower Ag release concentration (44.35 μg/L) and lower Ag release rate (0.27 %) after 14 days tests than those of PUF@Ag (7.93 mg/g, 80.87 μg/L and 0.60 % respectively). The CA/PUF@Ag was highly reusable because bacterial cells in the squeezed water recovered from the composite were completely inactivated over five cycles of operation, and exhibited good antibacterial efficacy as an antibacterial filter in a flow test.

Photoinduced Absorption Spectroscopy of Photoelectrocatalytic Methylene Blue Oxidation on Titania and Hematite: The Thermodynamic and Kinetic Impacts on Reaction Pathways

Photoelectrochemical oxidation of methylene blue is investigated, with particular focus on the difference in kinetics and thermodynamics of decoloration and mineralization employing photoinduced absorption spectroscopy. Hematite and titania photoanodes are used for the comparison of both reactions, which is determined to be associated with the depth of the valence band (3.2 vs 2.5 V for titania and hematite, respectively). Methylene blue is mineralized by the titania photoanode, however it is only oxidized to small fragments by hematite. Such difference is related to the valence band potential that provides the thermodynamic driving force for photogenerated holes in both materials. In addition, the kinetic competition of water oxidation is found to occur on titania by controlling the pH of the electrolyte. In the pH 14 electrolyte, mineralization of methylene blue is suppressed due to the faster and dominant kinetics of water oxidation, in contrast to the complete mineralization in the near neutral electrolyte where water oxidation kinetics are modest. These results clearly address the importance considering both thermodynamic and kinetic challenges of methylene blue oxidation, which has been thought to be an easy molecule to oxidize, as the model reaction in the application of photo(electro)catalysis using metal oxides.

Ag@AgCl nanoparticles grafted on carbon nanofiber: an efficient visible light plasmonic photocatalyst via bandgap reduction

A novel silver@silver chloride/carbon nanofiber (Ag@AgCl/CNF) hybrid was synthesized by electrospinning, heat treament, and subsequentin situchemical oxidation strategy. The synthesized materials were characterized using x-ray diffraction, Fourier-transform infrared, UV-Vis diffuse reflectance spectroscopy, scanning electron microscopy, and energy dispersive x-ray. The experimental results reveal that the electrospun AgNO₃/PAN was carbonized and reduced to Ag/CNF, the Ag/CNF was then partly oxidized to form Ag@AgCl/CNF in which Ag@AgCl nanoparticles (ca. 10-20 nm in diameter) were uniformly bounded to CNFs (ca. 165 nm in diameter). The obtained Ag@AgCl/CNF was employed for Na₂S₂O₈activation under visible light irradiation to treat Rhodamine B (RhB). A remarkable RhB removal of ca. 94.68% was achieved under optimal conditions, and the influence of various parameters on removal efficiency was studied. Quenching experiments revealed that HO•, SO₄^•-,¹O₂, and O₂^•-were major reactive oxygen species, in which O₂^•-played a pivotal role in RhB degradation. A possible mechanistic route for RhB degradation was proposed.

Phyto-mediated synthesis of nanoparticles and their applications on hydrogen generation on NaBH4, biological activities and photodegradation on azo dyes: Development of machine learning model

This work reports the synthesis of the silver-platinum bimetallic nanoparticles (N@Pt-Ag BNPs) reduced by an ethanolic extract of black seed (Nigella sativa, N) using the green synthesis method, these nanoparticles show a great antibacterial, anticancer, and catalytic activity. The characterization of physicochemical properties of Ag-Pt BNP was carried out using UV-visible spectroscopy (Uv-vis), Fourier-transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), and Transmission electron microscope (TEM) analysis. The structural morphology shows that the N@Pt-Ag BNPs are spherical particles with a diameter of 5.6 nm. The cytotoxic effects of N@Pt-Ag BNPs were examined by MTT test in human breast cancer, human colon cancer, human pancreatic cancer, L929-Murine fibroblast cells. N@Pt-Ag BNPs have been observed to be much more effective in breast cancer cell lines. The cytotoxic effect of N@Pt-Ag BNPs against healthy L929-murine fibroblast cell lines was not observed. Also, high antibacterial activity on each of the bacteria Escherichia coli (E. coli), Bacillus subtilis (B. subtilis), Methicillin-resistant Staphylococcus aureus (MRSA), Staphylococcus aureus (S. aureus), where we note that most strains of E. coli and S. aureus were damaged with a 73% percentage, 67% bacterial inhibition respectively. The results of the catalytic activities of N@Pt-Ag BNPs were obtained by performing the hydrolysis experiments of sodium borohydride (NaBH₄). According to the results obtained, TOF, enthalpy, entropy, and activation energy, values were found to be 2497.14 h^-1, 13.52 kJ/mol, -137.47 J/mol.K, 16.02 kJ/mol, respectively. N@Pt-Ag BNPs were found to be highly effective catalysts for hydrogen production which this was also confirmed by the machine learning model. The photocatalytic activity of N@Pt-Ag BNPs was tested against methylene blue (MB) dye and the highest activity was found as 80%.

Enhanced photocatalytic performance of ZnO/AgCl composites prepared by high-energy mechanical ball milling

ZnO/AgCl composites prepared by high-energy ball milling showed excellent photocatalytic activity for RhB degradation and 1,4-DHP dehydrogenation under visible-light irradiation.

Positively charged silver improve carbon dioxide electroreduction reaction performance by introducing phosphate

For noble metal catalysts such as Au and Ag, the weak adsorption of intermediates is an important factor in limiting the efficiency of CO₂ electroreduction. Positively charged metals, which can lower the energy barriers of intermediate reactions, greatly facilitate the rapid conversion of CO₂ molecules. In this work, a simple in situ synthesis method was utilized to form an Ag₃PO₄ oxide layer on the surface of Ag foil, and the oxidation state of silver retained after pre-reduction. The Ag₃PO₄/Ag catalyst not only increased the electrochemical surface area, but also enhanced the adsorption of intermediates to the active sites, resulting in the catalytic selectivity of 94.4% for the electroreduction of CO₂ to CO. DFT calculations show that through internal electron regulation, PO₄^3- can stabilize the positive state of Ag, thus increasing the Ag-O bond energy, which is conducive to the reduction of the reaction energy barrier and the improvement of catalytic stability.

Evaluation of synergistic effect from Ag-AgCl1/3Br1/3I1/3 composite on photocatalytic degradation the oil field pollutants

A series of Ag/AgX (X = Cl, Br, I; X = Cl, Br, or X = Cl, I, or X = Br, I; X = Cl, Br, and I) composite photocatalysts were synthesized via a facile photoreduction. The several characterization methods of X-ray diffraction (XRD), energy dispersive X-ray spectrometry (EDS) mapping and X-ray photoelectron spectroscopy (XPS) were characterized the samples. Through evaluation the photocatalytic activity of degradation rhodamine, methyl orange, and phenol, Ag-AgCl_1/3Br_1/3I_1/3 exhibited the superior selective photocatalytic activities than other photocatalysts. The reason for improved photocatalytic property of Ag-AgCl_1/3Br_1/3I_1/3 was attributed to the multifarious halogen atoms with the synergistic effect and the surface plasmon resonance (SPR) effect of Ag⁰. Furthermore, the recycle experiments were conducted to reveal the stability and reusability, the trapping experiments confirmed the active species of Ag-AgCl_1/3Br_1/3I_1/3.

In situ synthesis of Ag3PO4/C3N5Z-scheme heterojunctions with enhanced visible-light-responsive photocatalytic performance for antibiotics removal

Environmental pollution caused by antibiotics-containing wastewater has attracted increasing attention. Considering the superior photocatalytic performance and the issue of photo-corrosion over silver-based photocatalysts, it is desirable to construct silver-based photocatalysts with high photostability. Herein, a serious of Ag₃PO₄/C₃N₅ nanocomposites with Z-scheme band alignment were rationally designed and fabricated for tetracycline hydrochloride (TCH) removal. A variety of characterizations were employed to systematically study the phase structure, morphology and microstructure, optical properties, surface chemical states, and photocatalytic performance of the as-fabricated photocatalysts. The as-prepared Ag₃PO₄/C₃N₅ nanocomposites exhibited superior photocatalytic activity and photochemical stability than a single component toward TCH removal, meanwhile, the photocatalytic performance was not increased with the increasing amount of Ag₃PO₄. The possible photocatalytic mechanism (Z-scheme mechanism) was investigated and verified. The Z-scheme heterojunctions formed between Ag₃PO₄ and C₃N₅ is the main reason for the enhanced photocatalytic activities.

Sonochemical catalysis as a unique strategy for the fabrication of nano-/micro-structured inorganics

Ultrasound-assisted approaches, as an important trend in material synthesis, have emerged for designing and creating nano-/micro-structures. This review simply presents the basic principles of ultrasound irradiation including acoustic cavitation, sonochemical effects, physical and/or mechanical effects, and on the basis of the latest progress, it newly summarizes sonochemical catalysis for the fabrication of nano-structured or micro-structured inorganic materials such as metals, alloys, metal compounds, non-metal materials, and inorganic composites, where the theories or mechanisms of catalytic synthetic routes, and the morphologies, structures, sizes, properties and applications of products are described in detail. In the review, a few technological potentials and probable challenges of sonochemical catalysis are also highlighted for the future advance of synthesis methods. Therefore, sonochemical catalysis or ultrasound-assisted synthesis will serve as a unique strategy to reveal its great significance in material fabrication.

The Multiple Promotion Effects of Ammonium Phosphate-Modified Ag3PO4 on Photocatalytic Performance

Phosphate ( PO 4 3 - ) modification of semiconductor photocatalysts such as TiO₂, C₃N₄, BiVO₄, and etc. has been shown positive effect on the enhancement of photocatalytic performance. In the present study, we demonstrate a novel one-pot surface modification route on Ag₃PO₄ photocatalyst by ammonium phosphate [(NH₄)₃PO₄], which combines PO 4 3 - modification with ammonium ( NH 4 + ) etching to show multiple effects on the structural variation of Ag₃PO₄ samples. The modified Ag₃PO₄ photocatalysts exhibit much higher photocatalytic performance than bare Ag₃PO₄ for the degradation of organic dye solutions under visible light irradiation. It is indicated that the NH 4 + etching favors the surface transition from Ag₃PO₄ to metallic Ag nanoparticles, resulting in the fast capture of photogenerated electrons and the followed generation of O 2 · - radicals. The strongly adsorbed PO 4 3 - on the Ag₃PO₄ surfaces can further provide more negative electrostatic field, which improves the separation of photogenerated electron-hole pairs by inducing the holes to directly flow to the surface and then enhances the formation of reactive ·OH radicals. Furthermore, the photocatalytic performance of the modified Ag₃PO₄ photocatalysts can be optimized by monitoring the concentration of (NH₄)₃PO₄ that is 1 mM.

Fabrication of a three-dimensional visible-light-driven Ag–AgBr/TiO2/graphene aerogel composite for enhanced photocatalytic destruction of organic dyes and bacteria

The configuration of Ag–AgBr/TiO₂/GA integrated critical components of solar absorption and charge separation for environmental remediation and antibacterial treatment.