As-synthesized Ag Research Articles

Synergistic effect of noble metal doping and composite formation to boost the electrochemical properties of vanadium pentoxide

Herein, a hydrothermal method was used for the synthesis of V2O5 nanowires (NWs) and Ag-doped V2O5. The prepared doped material was intercalated in MXene for the preparation of an Ag-doped V2O5/MXene nanocomposite using a facile ultrasonication method. For structural and morphological confirmation, X-ray diffraction (XRD), Scanning electron microscopy (SEM), and Fourier transform infrared (FT-IR) spectroscopy were used. Additionally, for electrochemical measurements, cyclic voltammetry (CV), cyclic-charge discharge (CCD), and electrochemical impedance spectroscopy (EIS) were performed. To avoid the restacking of Al-etched layers of MXene, Ag–V2O5 nanowires were intercalated. This strategy ultimately increases the conductive channels, which helps in boosting the electrochemical properties of Ag–V2O5 nanowires. To fabricate electrodes, indium tin oxide (ITO) was used as a substrate. As prepared, the Ag-doped V2O5/MXene@ITO electrode showed a significant increase in the specific capacity. For the Ag-doped V2O5/MXene@ITO electrode, the calculated specific capacitance was 875 F/g (at 1 A/g) using galvanostatic charge-discharge (GCD) data. Also, it lost 6.1% of capacitance after the 3000th cycle. Results suggest that as-synthesized Ag–V2O5/MXene nanocomposite is a potential electrode material for energy storage.

Oak gum mediated green synthesis of silver nanoparticles under ultrasonic conditions: Characterization and evaluation of its antioxidant and anti-lung cancer effects

Herein, we represent the bio-synthesis of silver nanoparticles (Ag NPs) employing Oak gum as the green template, an efficient natural and non-toxic reductant and stabilizer based on its phytochemicals by using ultrasonic irradiation. The characterization of as-synthesized Ag NPs was performed through Fourier transformed infrared spectroscopy (FT-IR), scanning electron microscopy (SEM), transmission electron microscopy (TEM), energy dispersive X-ray spectroscopy (EDS), elemental mapping, UV–Vis and X-ray diffraction (XRD). After the characterization, the synthesized Ag NPs/O. Gum was engaged in biological assays like study of anti-oxidant properties by DPPH mediated free radical scavenging test using MeOH and BHT as reference molecules. Thereafter, on having a significant IC 50 value in radical scavenging assay, we extended the bio-application of the desired nanocomposite in anticancer study of A549, Calu6 and H358 human lung cell lines in-vitro through MTT assay. They had very low cell viability and high anti-human lung cancer activities dose-dependently against the cell lines without any cytotoxicity on the normal cell line (MRC-5). The IC 50 of Ag NPs/O. Gum was found 161.25, 289.26 and 235.29 µg/mL against A549, Calu6 and H358 cell lines, respectively. Maybe significant anti-human lung cancer potentials of Ag NPs/O. Gum against common lung cancer cell lines are related to their antioxidant activities. So, these results suggest that synthesized Ag NPs/O. Gum as a chemotherapeutic nanomaterial have a suitable anticancer activity against lung cell lines.

Green Synthesis of Silver Nanoparticles Using Juniperus procera Extract: Their Characterization, and Biological Activity

Plant extract-based green synthesis of metal nanoparticles (NPs) has become a popular approach in the field of nanotechnology. In this present investigation, silver nanoparticles were prepared by an efficient and facile approach using Juniperus procera extract as a bioreducing and stabilizing agent. The as-synthesized silver nanoparticles (JP-AgNPs) were characterized by several characterization techniques such as UV–Vis, XRD, FT-IR, HR-TEM, and EDX analysis. The XRD analysis evidently confirms that the as-synthesized Ag nanoparticles (NPs) from Juniperus procera plant extract (JP-AgNPs) are crystalline in nature. FT-IR analysis confirms that the plant extract plays a dual role as a bioreducing and capping agent, while HR-TEM revealed the spherical morphology of as-synthesized JP-AgNPs with the size of ~23 nm. Furthermore, the synthesized JP-AgNPs were evaluated for antibacterial properties against several bacterial and fungal strains such as Staphylococcus aureus (ATCC 12228), Escherichia coli (ATCC 25922), Pseudomonas aeruginosa (ATCC 27853), Proteus mirabilis (ATCC 4753), Cryptococcus neoformans (ATCC 16620), and Candida albicans (ATCC 885-653). The JP-AgNPs displayed an efficient mean zone of inhibition (MZI) at 50.00 µL for bacterial associated with fungal pathogens than the plant extract. Mainly, MZI values against microbial pathogens were as follows; E. coli (17.17 ± 0.72 mm), P. mirabilis (14.80 ± 0.17 mm), and C. albicans (14.30 ± 0.60 mm), whereas JP-AgNPs showed moderate activity against P. aeruginosa (11.50 ± 0.29 mm) and C. neoformans (9.83 ± 0.44 mm). Notably, the tested JP-AgNPs have displayed almost similar antimicrobial activities with that of standard antimicrobial drugs, such as streptomycin and nystatin. The enhanced antimicrobial activity of JP-AgNPs can be ascribed to the quality of resultant NPs including, uniform size, shape, and aqueous colloidal stability of nanoparticles.

Enhanced Thermoelectric Properties of Cu2SnSe3-Based Materials with Ag2Se Addition.

In this work, (Ag, In)-co-doped Cu2SnSe3-based compounds are prepared using a self-propagating high-temperature synthesis process. Ag2Se and as-synthesized (Ag, In)-co-doped Cu2SnSe3-based powders are mixed in a proportion according to the formula of Cu1.85Ag0.15Sn0.91In0.09Se3/x Ag2Se (x = 0, 3, 4, and 5%), which is followed by a subsequent plasma-activated sintering (PAS) to obtain consolidated composite bulks. A sandwich experiment is designed to reveal the evolution of the microstructure and phase composition of the composite samples during the PAS process. We investigate the reaction mechanism between Ag2Se and Cu2SnSe3-based matrix as well as the influence of Ag2Se on the phase composition, microstructure, and thermoelectric transport properties of the composites. Ag2Se addition is proven to be effective to improve Ag solubility in the Cu1.85Ag0.15Sn0.91In0.09Se3 matrix and introduce a CuSe secondary phase and an Ag-rich phase at grain boundaries. The electrical conductivity of Cu1.85Ag0.15Sn0.91In0.09Se3/x Ag2Se (x = 0, 3, 4, and 5%) composites decreases while the Seebeck coefficient increases with increasing Ag2Se addition, resulting in an optimized power factor. Moreover, benefiting from the collective phonon scattering at various defects induced by Ag2Se addition, the composite samples exhibit significantly suppressed lattice thermal conductivity, which reaches as low as 0.11 W m-1 K-1 at 700 K for the x = 5% sample. A peak figure-of-merit (ZT) of 1.26 at 750 K and an average ZT of 0.75 at 300-800 K are obtained for Cu1.85Ag0.15Sn0.91In0.09Se3/5% Ag2Se. This work provides an efficient way to improve average ZT values of Cu2SnSe3-based compounds for promising power generation at intermediate temperatures.

Decoration of graphene sheets with silver nanoparticles and their characterization

Graphene has been an emerging area of research since last decade. This fantastic material promises a wide variety of applications starting from electronics to biomedical fields. The properties of graphene can be enhanced by conjugating it with various other elements. The present work describes about the deposition of silver nano-particles via chemical synthesis onto in-house synthesized graphene nanosheets. It can be pointed out that application of infrared accelerates the synthesis process. Few layered graphene nanosheets (FLGNs) has been synthesized through electrochemical exfoliation technique. The colloidal graphene solution stabilized by citrate ions helps in the chemical reduction of AgNO3, which is essential in the formation of a nano-sized silver particulate layer (Ag NPs) over the graphene sheets. The presence of Ag NPs over the as-synthesized graphene was established by XRD, UV–VIS, FE-SEM and STM studies. The change in colloidal stability for the as-synthesized graphene and Ag NPs coated graphene was explained by the dynamic light scattering studies. The electronic characteristics of graphene coated Ag NPs was studied by scanning tunneling spectroscopy (STS) technique. The STS studies revealed that graphene with various numbers of coupled layers is responsible for the variations in the density of states (DOS) pattern. For Ag NPs-FLGNs, the spatial variations in the DOS spectra can be correlated to the size effects of the Ag NPs over the FLGNs. The local density of states (LDOS) spectra originates from the quantized electronic structure of the Ag NPs–FLGs system.

Single droplet 3D printing of electrically conductive resin using high aspect ratio silver nanowires

The incorporation of silver nanowires (Ag NWs) in digital light processing (DLP) 3D printing enables the fast production of electrically conductive composites. The polyvinylpyrrolidone (PVP)-free polyol synthesized Ag NWs, in particular, exhibits high aspect ratio and requires less time in both synthesis and post processing as opposed to the conventional hydrothermal method. In this study, Ag NWs were synthesized in less than 30 min using the PVP-free polyol method. Long and thin pentagonal Ag NWs synthesized at 170 °C had the highest aspect ratio of around 1000 among the three temperatures examined. The as-synthesized Ag NWs were mixed directly with the liquid thermoplastic polyurethane (TPU) resin to produce electrically conductive resin. The optimum Ag NW loading was determined based on their printability and electrical performance. In order to achieve high precision and material utilization efficiency, a modified 3D printing process was proposed to fabricate a controllable 3D structure with single droplet of electrically conductive resin. A 3D printed structure with 1.3 wt% Ag NWs loading exhibited the highest electrical conductivity of 14 mS/cm. Additionally, the curing speed of the electrically conductive resin was enhanced by 450% with the introduction of 10 phr of photoinitiator. The 3D printed structure with the optimized electrically conductive resin formulation was able to light up an LED with 3.5 V applied and the IV characteristic revealed that the printed structure exhibited conductivity in the range of conductive materials (R = 13.7 kΩ). • High aspect ratio silver nanowires were successfully synthesized under 30 min via a PVP free polyol method. • An electrically conductive 3D printing resin was formulated with high aspect ratio silver nanowires as the nanofillers. • The modified 3D printing process greatly improved the utilization efficiency of the electrically conductive resin.

Ultrasound assisted synthesis of silver titanate for the differential pulse voltammetric determination of antibiotic drug metronidazole

Highly electroactive transition metal oxides have been received great potential in antibiotic drug electrochemical sensors due to excellent features including ease of preparation, a large number of active sites, good conductivity , high stability, and selectivity . In this work, the perovskite-type silver titanate (Ag 2 TiO 3 ) was synthesized by ultrasound-assisted coprecipitation method. The structural and morphology were examined using typical analytical techniques such as X-ray diffraction (XRD) Fourier transform infrared spectroscopy (FT-IR), Raman spectrometry , field-emission scanning electron microscope (FE-SEM), transmission electron microscope (TEM), and X-ray photoelectron spectroscopy (XPS) analyzes confirmed the purity and the chemical composition of as-prepared Ag 2 TiO 3 . The Brunauer−Emmett−Teller analysis (BET) of as-synthesized Ag 2 TiO 3 displayed a specific surface area of 48.485 m 2 g −1 resulted in improved charge transfer resistance (R ct ) of 695 Ω. The cyclic voltammetry (CV) analysis revealed the superior electrochemical performance of Ag 2 TiO 3 than other electrodes towards metronidazole (MTZ) detection. Under optimized differential pulse voltammetric (DPV) studies, the modified electrode exhibits a wide linear range of 0.1–104.3 μM with the lowest detection limit of 0.011 μM and a sensitivity of 0.371 μA μM −1 cm −2 . Furthermore, the fabricated sensor displayed excellent cyclic stability, reproducibility, repeatability, and noticeable selectivity in potentially effective interfering compounds for the detection of MTZ. The constructed electrode delivered good sensitivity to MTZ in urine and tablet with acceptable recoveries. Schematic diagram of as-synthesized Ag 2 TiO 3 towards electrochemical sensing of MTZ. • Perovskite-type Ag 2 TiO 3 was prepared by a simple ultrasonication method. • The as-synthesized Ag 2 TiO 3 modified electrode was optimized for the loading catalyst, pH, scan rate, peak current, and peak potential at the electrochemical determination of MTZ. • The fabricated sensor shows an extensive linear response from 0.1 to 104.3 μM with a low detection limit of 0.011 μM. • MTZ was successfully applied in real samples with good sensitivity and appropriate results.

Monomer driven growth of catalytically active AgAu plasmonic nanoalloys

Ag–Au alloy nanoparticles were effortlessly synthesized with the seed Ag nanoparticles acting as sacrificial template for the effective reduction of Au3+ ions to Au0 atoms, augmented in the presence of the monomer, NVP (N-vinyl pyrrolidone) assimilated in specific solvents. The conventional spherical morphology of the different Ag–Au alloy molar compositions confirmed using TEM corroborates their red-shifted optical absorption spectra along with the strain induced XRD patterns in accordance with Vegard's law. FTIR spectroscopy depicts clearly the solvation property of NVP and also its respective molecular interaction of individual metal and alloy nanostructures. The amine group of NVP despite its possible steric hindrance seems to coordinate well with monometallic Ag nanoparticles; while for bimetallic Ag–Au nanoparticles, the combined amine and carbonyl groups plays a major role in stabilizing the nanostructure. No evidence of oligomerization/polymerization is observed even after the formation of respective nanoparticles, representing the intriguing configuration of the monomer NVP, the behavior of which seems equivalent to that of its long chain polymer counterpart, PVP. The catalytic properties of the as-synthesized Ag–Au alloy nanoparticles were carefully analyzed in comparison with other polymer/surfactant coated alloy nanoparticles and their significance is established in a cohesive manner.

Bio-mimetic synthesis of catalytically active nano-silver using Bos taurus (A-2) urine

Herein we have synthesized silver nanoparticles (Ag NPs) using liquid metabolic waste of Bos taurus (A-2 type) urine. Various bio-molecules present in cow urine, are effectively used to reduce silver (Ag) ions into silver nanoparticles in one step. This is bio-inspired electron transfer to Ag ion for the formation of base Ag metal and is fairly prompt and facile. These nanoparticles act as a positive catalyst for various organic transformation reactions. The structural, morphological, and optical properties of the as-synthesized Ag NPs are widely characterized by X-ray diffraction spectroscopy, ultraviolet–visible spectroscopy, scanning electron microscope, Fourier transmission infra-red spectroscopy, and atomic force microscopy. The as-synthesized bio-mimetic Ag NPs show potential activity for several reduction reactions of nitro groups. The Ag NPs were also used for degradation of hazardous dyes such as Methylene blue and Crystal violet with good degradation rate constant.

Facile one-pot green synthesis of Ag–Fe bimetallic nanoparticles and their catalytic capability for 4-nitrophenol reduction

The synergy between two different metals provides a dramatic enhancement in the bimetallic nanoparticles' catalytic properties since bimetallization improves the properties associated with the presence of two individual metals. Therefore, herein, we reported the facile, seedless, one-pot green synthesis of Ag–Fe bimetallic nanoparticles via reduction process using phytochemicals present in the Salvia officinalis aqueous extract. During the Phyto-assisted nanofabrication of Ag–Fe nanoparticles, the reduction of Ag+ and Fe3+ metal ions to Ag–Fe NPs takes place according to their reduction potential. The UV–visible spectroscopic technique was initially used for the Ag–Fe nanoparticle formation in which the absorption band at 450 nm, 350 nm, and 352 nm were observed for AgNPs, FeNPs, and Ag–Fe nanoparticles, respectively. Transmission electron microscopy (TEM) and scanning electron microscopy (SEM) analysis were used to investigate the size and shape of biosynthesized Ag–Fe nanoparticles, and it was revealed that the as-synthesized Ag–Fe nanoparticles are nearly spherical with an average size of 30 nm. X-ray diffraction (XRD) study was carried out to analyze the purity of the Ag–Fe nanoparticles. Fourier transform infrared spectroscopy (FTIR) analysis was performed to confirm the role of reducing and capping/stabilizing agents in the synthesis of Ag–Fe bimetallic nanoparticles. The successful biosynthesis of Ag–Fe nanoparticles was also confirmed by X-ray energy-dispersive spectrometry (EDX) analysis. Thermogravimetric analysis (TGA) was used to investigate the decomposition pattern of the Ag–Fe bimetallic nanoparticles. The catalytic behavior of as-synthesized Ag–Fe nanoparticles was investigated for the catalytic degradation of 4-nitrophenol to 4-aminophenol. The observed results revealed that Ag–Fe nanoparticles showed an efficient reduction of 4-Nitrophenol (4-NP) to 4-Aminophemol (4-AP) after 45 min of treatment.

Features of the formation of conductive films during thermal and laser sintering of silver nanoparticles stabilized by an ethoxylated carboxylic acid

Silver nanoparticles (Ag NPs) of ~ 6 nm in size were synthesized by the reduction of silver 2-[2-(2-methoxyethoxy)ethoxy]acetate by benzyl alcohol acting both as the solvent and as the reducer. The as-synthesized Ag NPs were dispersed in a mixture of nontoxic solvents with different boiling temperatures (butanol and propylene glycol ethers) to prepare ink. The ink was spin-coated on polyimide films and processed with thermal and laser sintering. After thermal sintering, the silver films have a non-uniform structure and contain many voids, causing their resistivity to be quite high (28 µΩ×cm). Laser sintering of the Ag NPs inks spin-coated on a polyimide film using a fiber laser operating at a wavelength of 1.064 µm in a pulse-periodic mode results in a uniform film structure, almost without voids, with a lower resistivity of 2.3 µΩ×cm. Laser sintering in this case is a promising method to fabricate conductive patterns on various substrates, including polymer flexible ones.

Synergistic effects of Ag-doped and morphology regulation of graphitic carbon nitride nanosheets for enhanced photocatalytic performance

In this study, a simple protocol for synthesizing silver doped and morphological regulation to improve the photocatalytic performance of g-C3N4 was reported. The as-synthesized single atom dispersed Ag doped graphitic carbon nitride nanosheets (Ag-CNNS) showed excellent performance for the degradation of 2-Mercaptobenzothiazole (MBT) and Rhodamine B (RhB) under visible light irradiation, mainly attributing to the synergistic effect of Ag doping and porous carbon nitride nanosheets (CNNS). On one hand, Ag doping promoted the capture and transfer of photogenerated electrons in g-C3N4. On the other hand, the presence of crimped nanosheets enabled g-C3N4 to have a larger specific surface area and shorten the charge diffusion distance from bulk to surface. Moreover, the increased photocurrent response proved that carriers had higher transport efficiency and interfacial catalytic reactivity. Cycle experiments confirmed that the 1% Ag-CNNS sample has good photocatalytic stability and reusability. Possible photocatalytic mechanism was proposed basing quenching experiment.

Photocatalytic activity enhancement for removal of dye molecules based on plasmonic Ag grafted TiO2 nanocubes under visible light driven

Introduction: Finding a novel photocatalyst for photocatalytic degradation operating in the wavelength range from UV to visible light has been considered a great potential for environmental remediation. Herein, TiO2 nanocubics (NCs) decorated Ag nanoparticles (NPs) with various concentrations were developed.
 Methods: The crystal structure, morphological and chemical characteristics of prepared photocatalysts were thoroughly analyzed by a series of main analyses (X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM), energy-dispersive X-ray spectroscopy (EDX), and UVVis spectra).
 Results: The results revealed that a significantly promoting visible-light photocatalytic behavior of TiO2NCs@Ag photocatalyst was observed. The photocatalytic methyl orange (MO) degradation of the as-synthesized Ag anchored TiO2NCs photocatalyst (85% and 62% under UV light and visible light, respectively) exhibited outstanding photocatalytic efficacy compared with pristine TiO2 NCs. The achieved results could be assigned to the synergistic effects between TiO2NCs and Ag- NPs, leading to enhanced charge carrier separation and improved absorption ability in visible-light response.
 Conclusion: This work facilitates designing and developing high-efficiency heterostructure photocatalysts for practical works related to environmental deterioration.

Quantifying Electrocatalytic Reduction of CO2 on Twin Boundaries

Summary A protocol relying on the use of silver nanostructures with well-defined dimensions and morphologies (e.g., nanocubes and nanowires) has been developed to differentiate and quantitatively determine the atom-specific activities of different surface atoms toward catalyzing electrochemical CO2 reduction reaction (CO2RR). The atom-specific activity of the twin-boundary edges (TBEs) is comparable to (or slightly higher than) that of the single-crystal edges (SCEs) formed from the crossing of two {100} surfaces, and it is on the order of ∼16 attoampere/atom (aA/atom) toward electrochemical CO2RR. This value is more than two orders higher than the atom-specific activity of the {100} surface atoms, i.e., ∼0.1 aA/atom. The high catalytic activity of the TBEs, which represent a class of commonly existing surface defects in stable metal nanostructures with face-centered cubic lattices, is consistent with the DFT calculations, in which the bridge-type binding configuration of COOH∗ at the TBEs stabilizes this intermediate to promote overall CO2RR.

Environmentally Benign and Large-Scale Synthesis of Monodisperse Oleate-Protected Silver Nanoparticles in Ethanol

An environmentally benign solvothermal process was introduced to synthesize monodisperse silver nanoparticles (Ag NPs). Silver nitrate (AgNO3) was reduced by ethanol which was also used for recyclable solvent. The as-synthesized Ag NPs were stabilized by oleate. Effects of reaction temperature, reaction time, AgNO3 concentration as well as molar ratio of sodium oleate and AgNO3 on the formation and surface plasmon resonance (SPR) were determined by means of UV–Vis spectrophotometer. TEM and XRD were used to characterize the size, morphology and crystalline structure of Ag NPs. The excessive AgNO3 over sodium oleate and high concentration of AgNO3 are favorable for the synthesis of monodisperse Ag NPs in large scale. The characteristic SPR absorption of Ag NPs centers at ca. 430 nm despite of reaction temperature, reaction time and even AgNO3 concentration. The nucleation and growth of Ag NPs completed in a very short period of time, showing the high efficiency of our synthetic route for the synthesis of uniform Ag NPs.

Boosting CO2 Conversion with Terminal Alkynes by Molecular Architecture of Graphene Oxide-Supported Ag Nanoparticles

Summary Carboxylation of terminal alkynes with CO2 via direct C–H bond activation is a highly appealing way to capture and convert CO2 but faces great challenges and difficulty. Here, we report an efficient catalyst that is prepared simply through introduction of p-tert-butylaniline into graphite oxide powders followed by localized growth of Ag nanoparticles (NPs). The bulky nature of p-tert-butylaniline facilitates the powder exfoliation, giving rise to mass production of uniform modified graphene oxide (tert-GO) nanosheets of 4 nm in thickness. Notably, Ag/tert-GO shows excellent catalytic activity for converting alkynes regardless of containing electron-donating or electron-withdrawing groups under mild reaction conditions. The synergy of the amide linkages on tert-GO nanosheets and the supported small-sized Ag NPs is recognized as the vital role in promoting adsorption of CO2 and subsequent conversion.

Proficient dye removal from water using biogenic silver nanoparticles prepared through solid-state synthetic route

An environmentally benign, one-pot and highly scalable method was presented to produce biogenic silver nanoparticles (Ag NPs) using the solid-state synthetic route. Four plant-derived candidate bio-reductants (i.e., Datura stramonium, Papaver orientale, Mentha piperita, and Cannabis sativa) were investigated to compare the efficiency of solid-state route and typical solution method. M. piperita was selected as the best plant resource to produce totally pure and uniform Ag NPs (average diameter of 15 nm) without any aggregation. The purity and size of biogenic Ag NPs, were tailored by adjusting the M. piperita leaf powder/silver nitrate weight ratio and temperature. The as-synthesized Ag NPs were effectively utilized as an eco-friendly nanoadsorbent in water remediation to remove a model dye (i.e., crystal violet). The key factors affecting on the sorption process (i.e., nanoadsorbent dosage, temperature, pH, dye initial concentration, and shaking time) were investigated. The pseudo-second-order kinetic model was well fitted to the sorption process and at the optimum sorption conditions, based on the Langmuir model, the adsorption capacity was found to be 704.7 mg/g. The current, cost effective and feasible method could be considered as an applicable strategy to produce green, reusable and proficient Ag NPs as nanoadsorbents for removal of dyes from contaminated water.

Synthesis of Nano-Flakes Ag•ZnO•Activated Carbon Composite from Rice Husk as A Photocatalyst under Solar Light

This study aimed to synthesize Ag•ZnO•Activated carbon (Ag•ZnO•AC ) composite from rice husk for degradation of dyes. The deposition of Ag and ZnO on AC led to decreasing the surface area and pore volume of Ag•ZnO•AC composite. In addition, when Ag and ZnO were dispersed on activated carbon, the Ag•ZnO flakes became denser and tighter, but the particle size of Ag became smaller from 5 to 7 nm. The photocatalytic ability of Ag•ZnO•AC composite was evaluated by degradation of Janus Green B (JGB) and compared with that of AC, ZnO, Ag•ZnO, and ZnO•AC samples. The effects of catalyst dosages, pH values, and initial dye concentrations on photocatalytic degradation were investigated in detail. The Ag•ZnO•AC composite had a high degradation efficiency of 100% in 60 min, showing the reaction rate of 0.120 min-1 and degradation capacity of 17.8 mg/g within 20 min. The photocatalytic performance of the Ag•ZnO•AC composite was also evaluated by cyclic test and the degradation of other persistent dyes such as Methylene Blue, Tartrazine, Congo Red, and organic compounds (Caffeine and Bisphenol A). Based on the experimental results, the possible destruction route of JGB by the as-synthesized Ag•ZnO•AC composite was suggested. Copyright © 2020 by Authors, Published by BCREC Group. This is an open access article under the CC BY-SA License (https://creativecommons.org/licenses/by-sa/4.0).

Controllable Electrochemical Synthesis of Ag Hierarchical Micro/Nanostructures with High SERS-Activity

We report a one-step electrochemical deposition technique to prepare three-dimensional (3D) Ag hierarchical micro/nanostructured film consisting of well-crystallized Ag nanosheets grown on an indium tin oxide (ITO) conductive substrate. The Ag hierarchical micro/nanostructures were fabricated in the mixed solution of AgNO3 and sodium citrate in a constant current system at room temperature. Through reduction of Ag[Formula: see text] electrodeposited on the surface of ITO substrate, nanoparticles were grown to form nanosheets which further combined into 3D sphere-like microstructures. The 3D Ag micro/nanostructures have many sharp edges and nanoscale gaps which can give rise to good Raman-enhanced effect. Due to localized surface plasmon resonance (LSPR) effects, these special Ag micro/nanostructures exhibited good Raman-enhanced performance. Using Rhodamine 6G (R6G) molecules as probe molecule, we studied the influence of excitation wavelength on Raman enhancement. The results showed that the 532[Formula: see text]nm excitation wavelength is the best to obtain the strongest Raman signal and to reduce the influence of other impurity peaks. Using the as-synthesized Ag hierarchical micro/nanostructures, we can detect the 10[Formula: see text][Formula: see text]mol/L R6G aqueous solution, exhibiting great Raman-enhanced effect.

Hierarchically 3D Porous Ag Nanostructures Derived from Silver Benzenethiolate Nanoboxes: Enabling CO2 Reduction with a Near-Unity Selectivity and Mass-Specific Current Density over 500 A/g.

Silver nanostructures with hierarchical porosities of multiple length scales have been synthesized through electrochemical reduction of silver benzenethiolate nanoboxes. The porous Ag nanostructures exhibit superior catalytic performance toward electrochemical reduction of CO2. The Faradaic efficiency of reducing CO2 to CO can be close to 100% at high cathodic potentials, benefiting from the readsorbed benzenethiolate ions on the Ag surface that can suppress the hydrogen evolution reaction (HER). Density functional theory calculations using the SCAN functional reveal that the disfavored H binding on the benzenethiolate-modified Ag surface is responsible for inhibiting the HER. The mass-specific activity of CO2 reduction can be over 500 A/g because the multiple-scale porosities maximize the diffusion of reactive species to and away from the Ag surface. The unique multiscale porosities and surface modification of the as-synthesized Ag nanostructures make them a class of promising catalysts for electrochemical reduction of CO2 in protic electrolytes to achieve maximum activity and selectivity.