Bare Ag Research Articles

Boosting the bifunctional catalytic activity of Co3O4 on silver and nickel substrates for the alkaline oxygen evolution and reduction reactions

Developing an efficient bifunctional catalyst for oxygen reduction (ORR) and evolution reactions (OER) is a crucial step for the wide commercialization of alkaline water electrolyzers. However, a proper assessment and comparison of various catalysts is still challenging due to the different catalyst substrates and loadings. In this work, Co3O4 spinel nanoparticles (NPs) were investigated as a bifunctional catalyst at different substrates of glassy carbon or Ag bulk substrate or Ni particles and with different loadings. For Co3O4 (800 µg cm-2)/Ag electrode, not only the overpotential for ORR was 50 mV lower than the bare Ag electrode, but also the OER overpotential was 40 mV lower than the sole Co3O4. Besides, less than 1% peroxide intermediate was detected during ORR using the rotating ring disc electrode (RRDE) method, suggesting a 4-electron O2 reduction. Tafel slopes of 70 and 60 mV dec‑1 at Co3O4/Ag were obtained for ORR and OER, respectively. The improved bifunctional activity could be attributed to a synergistic effect between Co3O4 and the Ag support. For the loading effect, it is revealed that the number of accessible sites of Ag surface decreases with increasing the Co3O4 loading, as evaluated from lead-underpotential deposition measurements. Interestingly, after running ORR/OER cycles, the surface area increased by 4–6 times. This surface roughening was also confirmed by SEM and EDX. The study was extended to Co3O4+Ni mixed catalyst to validate the effect of the support on this induced synergism. Hence, this work provides a simple route for designing potential effective catalytic interfaces and contributes to unravelling the influence of the substrate and loading on the catalyst activity for water electrolyzers.

Advanced Prussian Blue Cathodes for Rechargeable Li-Ion Batteries

Taking advantage of fact that the surface electrons of metallic nanoparticles (NPs) can be effectively released even at a low voltage bias, we demonstrate an improvement in the electrochemical performance of nanosized Prussian Blue (PB)-based secondary batteries through the incorporation of bare Ag or Ni NPs in the vicinity of the working PB NPs. It is found that the capacity for electrochemical energy storage of the 17 nm PB-based battery is significantly higher than the capacity of 10 nm PB-based, 35 nm PB-based or 46 nm PB-based batteries. There is a critical PB size for the highest electrochemical energy storage efficiency. The full specific capacity CF of the 17 nm PB-based battery stabilized to 62 mAh/g after 130 charge–discharge cycles at a working current of IW = 0.03 mA. The addition of 14 mass percent of Ag NPs in the vicinity of the PB NPs gave rise to a 32% increase in the stabilized CF. A 42% increase in the stabilized CF could be obtained with the addition of 14 mass percent of Ag NPs on the working electrode of the 35 nm PB-based battery. An enhancement in CF was also found for electrodes incorporating bare Ni NPs but the effect was smaller.

Bio-surfactant mediated sustainable exfoliation of MoS2 and in-situ preparation of Ag@MoS2 nanocomposites for photocatalysis under sunlight in aqueous medium

Exfoliation of MoS2 has been performed in the aqueous solution of bio-based surfactant choline deoxycholate, ([Cho][Doc]), employing low-energy bath sonication. The ability of [Cho]+ to reduce the Ag+ under sunlight accompanied by the templating effect of [Doc]− has been exploited to decorate the exfoliated MoS2 in a single step. The dimensions as well as the extent of adherence of Ag NPs to MoS2 in Ag@MoS2 nanocomposites (NCs) have been controlled by adjusting the concentration of [Cho][Doc]. The prepared NCs have been characterized by UV–vis spectroscopy, atomic force microscopy (AFM), dynamic light scattering (DLS), zeta-potential measurements (ζ-potential), X-ray diffraction (XRD), Raman spectroscopy, X-ray photon spectroscopy (XPS), transmission (TEM) and high-resolution transmission electron microscopy (HR-TEM). The NCs have shown enhancement in photocatalytic activity compared to bare Ag NPs under sunlight in an aqueous medium. It has been observed that the Schottky junction between metallic Ag NPs and semiconductor MoS2 in NCs shows efficient charge separation by generating a continuum-charged region resulting in increased catalytic activity of NCs. The present work is expected to serve as a platform for preparing photocatalytic NCs sustainably employing various other 2D materials.

Harmonizing Plasmonic and Photonic Effects to Boost Photocatalytic H2 Production over 550 mmol ⋅ h−1 ⋅ gcat−1

AbstractIntegrating plasmonic nanoparticles with photonic crystals holds immense potential to enhance green hydrogen photosynthesis by amplifying localized electromagnetic field through generating surface plasmons and slow photons. Current plasmonic photonic designs primarily employ semiconductor‐based structural backbone deposited with plasmonic nanoparticles. However, the competition between various optical phenomena in these ensembles hinders effective field enhancement rather than facilitating it. This limitation creates a formidable performance bottleneck that retards hydrogen evolution. Herein, we enhance plasmonic catalysis for efficient hydrogen evolution by effectively harmonizing plasmonic and photonic effects. This is achieved by using inert SiO2 opal as a non‐photoabsorbing photonic framework. By aligning the excitation wavelengths of surface plasmons and slow photons, our optimized plasmonic photonic crystals demonstrates a remarkable H2 evolution rate of 560 mmol h−1 gAg−1, surpassing bare plasmonic Ag nanoparticles by >106‐fold and other high‐performance photocatalytic designs by 280‐fold. Mechanistic studies highlight the pivotal role of the non‐photoabsorbing photonic backbone in facilitating effective light confinement through the photonic effect. This in turn boosts the plasmonic field for enhanced photocatalytic H2 evolution, even without needing additional co‐catalysts. Our work offers valuable insights for future design of electromagnetically hot plasmonic catalysts to achieve efficient light‐to‐chemical transformations in diverse energy, chemical, and environmental applications.

Harmonizing Plasmonic and Photonic Effects to Boost Photocatalytic H2 Production over 550 mmol ⋅ h-1 ⋅ gcat -1.

Integrating plasmonic nanoparticles with photonic crystals holds immense potential to enhance green hydrogen photosynthesis by amplifying localized electromagnetic field through generating surface plasmons and slow photons. Current plasmonic photonic designs primarily employ semiconductor-based structural backbone deposited with plasmonic nanoparticles. However, the competition between various optical phenomena in these ensembles hinders effective field enhancement rather than facilitating it. This limitation creates a formidable performance bottleneck that retards hydrogen evolution. Herein, we enhance plasmonic catalysis for efficient hydrogen evolution by effectively harmonizing plasmonic and photonic effects. This is achieved by using inert SiO2 opal as a non-photoabsorbing photonic framework. By aligning the excitation wavelengths of surface plasmons and slow photons, our optimized plasmonic photonic crystals demonstrates a remarkable H2 evolution rate of 560 mmol h-1 gAg -1, surpassing bare plasmonic Ag nanoparticles by >106-fold and other high-performance photocatalytic designs by 280-fold. Mechanistic studies highlight the pivotal role of the non-photoabsorbing photonic backbone in facilitating effective light confinement through the photonic effect. This in turn boosts the plasmonic field for enhanced photocatalytic H2 evolution, even without needing additional co-catalysts. Our work offers valuable insights for future design of electromagnetically hot plasmonic catalysts to achieve efficient light-to-chemical transformations in diverse energy, chemical, and environmental applications.

Improved photocatalytic activity of graphene oxide modified Ag-TiO2 for degradation of piroxicam-20 and dehydrogenation of methanol under light irradiation

BackgroundGraphene oxide (GO), an atomic sheet structure made of sp2-bonded carbon atoms with superior optoelectronic, and catalytic properties, has attracted much interest. Incorporating a carbon-rich material, onto metal-loaded TiO2 is reported to increase the photocatalytic properties of resultant composites. MethodsThis research aimed at the deposition of different amounts (1–5 wt.%) of GO using the ultrasonication method on bare TiO2 and Ag (3 wt.%)-TiO2 (AT3) and studied their influence on piroxicam-20 degradation under visible light and methanol dehydrogenation under UV light. The prepared composites' structural, optical, and morphological properties were characterized using XRD, DRS, HR-TEM, FE-SEM, and XPS. Significant findingsHRTEM analysis confirmed the existence of GO layers and spherical-shaped Ag nanoparticles deposited over the TiO2 surface. GO(5 wt.%)@Ag(3 wt.%)-TiO2 (G5@AT3) displayed better photodegradation efficiency (78 %) (k = 0.0082 min−1) under 120 min, and GO(1 wt.%)@Ag(3 wt.%)-TiO2 (G1@AT3) composite produced higher amount (427 mmol) of H2 from photocatalytic dehydrogenation of CH3OH under 5 h relative to TiO2 (2 mmol), AT3 (166 mmol) and GO(5 wt.%)@TiO2 composite (GT5) (11 mmol). HRMS analysis was performed to identify the piroxicam-20 degradation intermediates. Thus, this research provides a proactive strategy highlighting the cooperative effect of Ag and GO loading to improve the photocatalytic efficiency of TiO2 photocatalyst using both UV–visible light irradiation.

Highly transparent and low resistance BaSnO3/Ag nanowire composite thin films

Highly transparent and low resistance composite thin films with a bilayer structure composed of barium stannate (BSO) and silver nanowires (Ag NWs) are manufactured on polycarbonate (PC) substrates. The Ag NW networks are embedded into the BSO thin films prepared by magnetron sputtering. The BSO/Ag NW composites possess low sheet resistance of 9.1 Ω/sq. and high transmittance of 84.7 % at four spin-coating cycles, these are superior to that of bare Ag NWs and flexible ITO films. The mechanisms of improved transmittance and conductivity of BSO/Ag NW composites are proposed. The resistance remains mostly intact after beading tests at curvature radius of 3.0 mm and taping tests with 30 cycles, indicating the excellent flexibility and adhesiveness. More importantly, the BSO/Ag NW composites possess excellent oxidation resistance, thermal and chemical stabilities. These results suggest that BSO/Ag NW composites can be utilized for the fabrication of flexible electronics.

Selective Thermal and Photocatalytic Decomposition of Aqueous Hydrazine to Produce H2 over Ag-Modified TiO2 Nanomaterial.

An Ag-modified TiO2 nanomaterial was prepared by a one-pot synthesis method using tetra butyl titanate, silver nitrate, and sodium hydroxide in water at 473 K for 3 h. X-ray diffraction, scanning electron microscopy, and transmission electron microscopy were used to determine the structure and morphology of the synthesized Ag-modified TiO2 nanomaterial. The diffuse reflectance UV-visible and photoluminescence spectroscopy results revealed that metallic Ag nanoparticles decreased the optical band gap and photoluminescence intensity of the TiO2. In addition, the Raman peak intensity and absorbance were increased after Ag modification onto TiO2. The photocatalytic efficiency of the synthesized samples was tested for decomposition of aqueous hydrazine solution under visible light irradiation. The photocatalytic efficiency of Ag-modified TiO2 nanomaterials was higher than that of bare TiO2 and Ag metal NPs due to the synergistic effect between the Ag metal and TiO2 structures. In addition, the surface plasmon resonance (SPR) electron transfer from Ag metal particles to the conduction band of TiO2 is responsible for superior activity of TiO2-Ag catalyst. The Ag-modified TiO2 nanomaterials offered a 100% H2 selectivity within 30 min of reaction time and an apparent rate constant of 0.018 min-1 with an activation energy of 34.4 kJ/mol under visible light radiation.

From Self-Affine Ag to Mounded Ag@Ag2O Core–Shell Nanoplasmonic Surfaces By Sonochemistry

A controllable ultrasound-assisted synthetic approach has been developed that allows deposition of elemental silver and core–shell Ag@Ag2O nanoparticles, close-packed in thin-film form on glass substrates, suitable for a wide range of applications. Ultrasonic irradiation modifies the reaction mechanism, allowing precise control over the composition of the nanoparticles and their packing in the form of thin films. The crystal radii of the synthesized materials fall within the nano range (∼9 nm in the case of bare Ag, 5 nm for the Ag core, and 9 nm for the Ag2O shell in the case of Ag@Ag2O films). Nanostructured Ag films exhibit self-affine, while the films built up by Ag@Ag2O core–shell nanocrystals exhibit a mounded morphology. The interface width and the mean roughness are significantly smaller for sonochemically synthesized surfaces. The observed trends in the localized surface plasmon resonance (LSPR) absorptions in the case of bare Ag plasmonic surfaces are dominated by the particle size, inhomogeneous broadening induced by the size dispersion of the nanoparticles, interparticle plasmon coupling, and nanocrystal–substrate interaction. The notable red shift of the LSPR absorption maximum in the case of films built up by Ag@Ag2O core–shell nanoparticles is governed by the influence of the dielectric shell.

Comparative analysis of Ag NPs functionalized with olive leaf extract and oleuropein and toxicity in human trophoblast cells and peripheral blood lymphocytes.

Dry olive leaf extract (DOLE) and its active component oleuropein (OLE) were applied as reducing and stabilizing agents to prepare colloidal 20-25 nm silver nanoparticles (Ag NPs). The Ag NPs were characterized using transmission electron microscopy, X-ray diffraction analysis, and absorption spectroscopy. The cytotoxic actions of coated Ag NPs, and their inorganic and organic components, were examined against trophoblast cells and human peripheral blood lymphocytes (PBLs), Gram-positive, Gram-negative bacteria, and yeast. The genotoxic potential was evaluated in PBLs in vitro with the comet assay. Ag/DOLE and Ag/OLE induced cytotoxic effects in both types of cells after 24 h exposure when silver concentrations were 0.025-0.2 mM. However, the most pronounced cytotoxicity exhibits Ag/OLE. Both colloids also caused reduced ROS production in both cell types at 0.1 mM and 0.2 mM, while bare Ag NPs did not alter ROS levels at any of the conditions. Functionalized Ag/DOLE and Ag/OLE did not show genotoxic effects in PBLs, while bare AgNPs increased DNA damage significantly only at 0.2 mM. Regarding the antimicrobial effects, the Ag/OLE had MIC values for all evaluated microorganisms from 0.0625 to less than 0.0312 mM. Also, the antimicrobial effect of Ag/DOLE was significantly higher on Gram-negative bacteria and yeast than on Gram-positive bacteria. Obtained results indicate that Ag/OLE induced the most pronounced biological effects, beneficial for its application as an antimicrobial agent, but with potential risks from exposure to high concentrations that could induce cytotoxicity in healthy human cells.

Formation of SiO2-Encapsulated Ag Nanoparticles on SiO2 Nanofibers and Their Application as Robust, Flexible Pressure Sensor Working under High Temperatures

Lightweight, flexible pressure sensors working under high temperatures have intrigued great research interest owing to their potential in firefighting, aerospace technology, and automotive and petroleum industries. Here, we propose a strategy to prepare SiO2 shell-coated Ag nanoparticles on SiO2 nanofiber membranes (SNFs), which prohibit nanoparticle migration and fusion. The reduction treatment of the nanofiber membrane promotes the in situ reduction of AgNO3 into Ag seeds, which further grow as Ag nanoparticles in the following wet-chemical treatment. Then, a protective silica layer is fabricated on the Ag nanoparticles, which effectively prevents the nanoparticles’ migration and fusion; we propose that metal–support interaction (MSI) may help to form the silica coatings on the Ag nanoparticles. The as-formed Ag nanoparticles with a SiO2 coating layer are sinter-resistant and show much higher thermal stability than bare Ag nanoparticles on the nanofibers. The as-assembled pressure sensors using these SNFs as active materials can continuously work at 350 °C without performance decay. After annealing the SNF at 600 °C for 2 h, the SNF can still maintain its performance as a pressure sensor. The high-sensitivity, high-temperature-resistant, and robust SNF may provide a platform for unconventional pressure sensor construction. The strategies used in this study may bring insights into both the design and application of these sinter-resistant nanostructures.

Conformal and Transparent Al2O3 Passivation Coating via Atomic Layer Deposition for High Aspect Ratio Ag Network Electrodes

We demonstrated conformal Al2O3 passivation via atomic layer deposition (ALD) of a flexible Ag network electrode possessing a high aspect ratio. The Ag network electrode passivated by the ALD-grown Al2O3 film demonstrated constant optical transmittance and mechanical flexibility relative to the bare Ag network electrode. Owing to the conformal deposition of the Al2O3 layer on the high aspect ratio Ag network electrode, the electrode exhibited more favorable stability than its bare Ag-network counterpart. To demonstrate the feasibility of Al2O3 passivation via ALD on a flexible Ag network, the performances of flexible and transparent thin-film heaters (TFHs) with both a bare Ag network and that passivated by ALD-grown Al2O3 were compared. The performance of Al2O3/Ag network-based TFHs was minimally altered even after harsh environmental tests at 85% relative humidity and a temperature of 85 °C, while the performance of bare electrode-based TFHs significantly deteriorated. The improved stability and reliability of the Al2O3/Ag network-based TFHs indicate that the ALD-grown Al2O3 film effectively prevents the introduction of moisture and impurities into the Ag network with a high aspect ratio. The improvement in the stability of the Ag network through Al2O3 passivation implies that the ALD-grown Al2O3 film represents a promising transparent and flexible thin film passivation material for high quality Ag network electrodes with high aspect ratios.

Studies of surface plasmon resonance effect on different metallic layers of silver (Ag) and copper (Cu) with molybdenum trioxide (MoO3) for formaldehyde sensor

This paper reports the implementation of surface plasmon resonance in optical fiber sensor for formaldehyde detection. The studies involve comparison effects of different metallic layer of silver (Ag) and copper (Cu) to enhance evanescence wave in optical fiber sensor (OFS). We integrate the MoO3 materials due to its natural advantage where it can be used as high-activity metal oxide catalyst. The sensor will be focusing on sensing formaldehyde which is an environmental pollutant and is considered hazardous if more than 0.1 ppm is inhaled. MoO3 contributes to the sensitivity enhancement and improvement of the oxidation resistance on the metal films. The independent variables are the different metal films namely Ag and Cu at 40 nm thickness obtained from previous work. Formaldehyde sensing using bare Cu film, bare Ag film and the combination of Cu/Ag-MoO3 is compared via transmission-wavelength graphs to check if there is sensitivity enhancement in the Cu/Ag-MoO3 combination. Ag-MoO3 displays a better red shift with formaldehyde, by 10 nm at a resonant wavelength of 350 nm where Cu shows highest responsive metallic layer in formaldehyde detection.

Boosting the electrochemical performance of Prussian-Blue-analogue based Li-ion rechargeable batteries by the addition of Ag or Ni nanoparticles into the cathode

The poor cyclability of Prussian-blue-analogue (PBA) based rechargeable Li-ion batteries places a limitation on their practical applications. Here, we demonstrate that the addition of bare Ag or Ni nanoparticles (NPs) into the vicinity of the nano-sized PBA particles can effectively improve the electrochemical performance of the batteries, leading toward a higher energy storage capacity. The addition of 14 mass-percent of 13.6 mm Ag NPs into the vicinity of the 120 nm K0.58Co[Co(CN)6] NPs gives rise to a 260 % increase in the stabilized full specific capacity CF, and the addition of 14 mass-percent of 12.4 nm Ni NPs gives rise to an 86 % increase of the stabilized CF. The addition of Ag or Ni NPs was also found to enhance the CF for the 80 nm Na0.46Co[Fe(CN)6]-based Li-ion batteries but the effect was smaller. It is the participations of the redox reactions of weakly bonded surface electrons on the Ag/Ni NPs that enhances the energy storage capacity of the battery.

One-step electrodeposition to fabricate superhydrophobic surfaces on flexible conductive films: Optimization of metallic compounds

Superhydrophobic surfaces were fabricated by a simple one-step electrodeposition technique to deposit three distinct micro/nano hierarchical structures of Ce, Mg, or Cu-based compounds on Ag films on a flexible polymer substrate. Scanning electron microscopy was used to examine the surface morphologies of obtained structures with different deposition. Compared with the bare Ag films, one-step electrodeposition process resulted in superhydrophobicity, including a water contact angle of 159.7° for Ce-modified surfaces, 157.0° for Mg-modified surfaces, and 153.8° for Cu-modified surfaces. Besides, these surfaces showed high thermal stability below 120 ℃, and good flexibility but low electrical conductivity. EDS and XPS results suggest the production of low surface energy materials that formed the superhydrophobic features on the Ag films. Besides, because of the formation of CeO2, Ce-SHS had better superhydrophobicity than Mg-SHS and Cu-SHS. In addition, the potentiodynamic polarization experiments showed that the electrodeposited superhydrophobic surfaces had lower Icorr, higher Ecorr and impedance values in NaCl solution, Na2SO4 solution and Simulated body fluid, and artificial sweat solution compared with the bare silver film, indicating that the electrodeposited protective film has good anti-corrosion properties. These results suggest that the one-step electrodeposition method is a promising strategy to fabricate conducting films with superhydrophobic surfaces for surface protection under various corrosive environments.

Electron Paramagnetic Resonance Quantifies Hot-Electron Transfer from Plasmonic Ag@SiO2 to Cr6+/Cr5+/Cr3+

Understanding the plasmon-mediated electron-transfer mechanisms from plasmonic nanostructures to redox-active metals is a technically challenging and still developing procedure. Electron paramagnetic resonance (EPR) spectroscopy is well established as a state-of-the-art tool to selectively detect the redox evolution of paramagnetic metals; however, its use in plasmon-driven charge-transfer processes has not been explored so far. Herein, we present a quantitative study on the mechanism of hot-electron transfer, from plasmonic Ag@SiO2 nanoaggregates, to drive sequential Cr6+ reduction toward Cr5+/Cr3+. Employing flame spray pyrolysis (FSP), core–shell Ag@SiO2 nanoaggregates were engineered with varying SiO2-shell thickness, in the range of 1–5 nm. Using EPR spectroscopy, the spin Hamiltonian parameters for the S = 1/2 {oxalate-Cr5+} and S = 3/2 {oxalate-Cr3+} systems at the Ag@SiO2/Cr interface are analyzed and used to quantitatively monitor the sequential electron-transfer steps during Cr6+ reduction. In the absence of the SiO2 shell, the oxidative path via the dark reduction of Cr6+ due to the oxidation of bare Ag was deducted accordingly. Importantly, we show that the SiO2 shell plays a key role in hot-electron transfer, as the 1 nm shell allows a predominant hot-electron transfer via a light-induced decrease of the activation barrier, suppressing the oxidative path and excluding photothermal effects.

Development of visible light-driven SrTiO3 photocatalysts for the degradation of organic pollutants for waste-water treatment: Contrasting behavior of MB & MO dyes

Semiconductor photocatalysts were utilized widely for degrading organic pollutants in water using the advanced, environment-friendly, low-cost, and highly efficient photocatalysis technique. There are various complex energy-consuming techniques used for the refinement of wastewater. However, the photocatalysis process is the cleanest technique used for degrading organic pollutants in wastewater into the water; carbon dioxide, other small molecules, and inorganic pollutants were reduced or oxidized into harmless substances.SrTiO3 nanoparticles (NPs) synthesized by the chemical method are the topic of attention among researchers because of their physical, chemical & photocatalytic properties under sunlight for water purification applications. This paper dealt with the study of The photocatalytic properties of SrTiO3 and its composites under sunlight irradiation. Here, we evaluated the photodegradation of methyl orange (MO) and methylene blue (MB) pollutants using SrTiO3 as a photocatalyst for de-ionized (DI) water and hard water, respectively. Later on, the ex-situ decoration of Ag and Au nanoparticles (NPs) on SrTiO3 NPs results in enhancing the photocatalytic activity of SrTiO3. This article shows the abnormal behaviour of MO degradation compared to MB dye because there was no degradation of methyl orange for both bare SrTiO3 and Ag, Au@SrTiO3 nanocomposites. However, for bare-SrTiO3, the photocatalytic degradation of MB dye for de-ionized and hard water was accomplished in 210 min and 300 min, respectively. Here, SrTiO3 with MB dye shows enhanced photocatalytic activity for de-ionized water than hard water, and thus we determined the degradation of SrTiO3 nanocomposites with DI water only. While in the case of SrTiO3 nanocomposites, degradation occurred in 210min for Ag and 180 min for Au in DI water which signifies that Au a better co-catalyst for photodegradation. Although, degradation of MO in both DI water and hard water does not show any photocatalytic activity even in 6 and 7 h, respectively, for bare SrTiO3 and its nanocomposites. Therefore, it gives an idea about the different behaviour of dyes in photocatalytic degradation of DI and hard water using bare SrTiO3 and noble metal doped SrTiO3 as photocatalysts for water remediation applications.At a glimpse, this work focus on the photocatalytic removal of various water pollutants using the efficient noble metal (Au & Ag) doped SrTiO3 as a photocatalyst and discusses the properties of those materials and also discuss the prospects for the utilization of those photocatalysts in complex form for the wastewater treatment.

Sidechain‐Engineered N‐PDIs Processed from Ethyl Acetate as Effective Cathode Interlayers for Organic Solar Cells

Herein, series bay position‐substituted N‐annulated perylene diimide (N‐PDI) derivatives applied as the cathode interlayer (CIL) in bottom‐anode (conventional structure) organic solar cells (OSCs) are presented. Despite the fact that N‐PDIs show low solubility in common CIL‐processing solvents such as methanol (MeOH), the use of ethyl acetate (EtOAc) as a processing solvent allows for dissolution of N‐PDIs at sufficient concentrations to form homogeneous films on top of the organic photoactive layer. OSC devices fabricated in ambient conditions using the PM6:Y6 representative bulk heterojunction (BHJ) system show simultaneous enhancements in performance metrics, with power conversion efficiency (PCE) increasing from 8.5% for devices based on the bare Ag cathode to 12.5% with N‐PDI molecule as CIL. The improvement in performance with N‐PDI CILs can be attributed to a combination of smooth film morphology and high electron extraction capability of N‐PDIs. Solubility in EtOAc, appropriate highest occupied molecular orbital/lowest unoccupied molecular orbital energy levels, uniform film formation, and facilitation of electron transfer/collection make these N‐PDIs a promising family of CIL materials for efficient OSCs. Using EtOAc as an improved solvent over MeOH also opens the door for new CIL designs and to test materials that are not MeOH soluble.

Cationic surfactant controlled synthesis of Ag2ZrO3 and Ag/Ag2ZrO3: An efficient visible light active photocatalysts

• Novel spherical Ag/Ag 2 ZrO 3 nanocomposite and Ag 2 ZrO 3 have been synthesized by a facile co-precipitation method. • The effect of surfactant cetyl trimethyl ammonium bromide has been investigated. • In-situ development of zero-valent silver on the surface of silver zirconate using strong bases (KOH and NaOH). • Enhanced photocatalytic activity can be attributed to the presence of zero-valent silver. Here we report the optimized route for the synthesis of zero valent silver loaded silver zirconate (Ag/Ag 2 ZrO 3 ) nanocomposite via a facile co-precipitation method for enhancing the visible light harvesting ability of silver zirconate (Ag 2 ZrO 3 ) by employing the surface plasmon resonance (SPR) effect of Ag 0 loaded on Ag 2 ZrO 3 and their photocatalytic efficiency has been investigated. The effect of the use of surfactant cetyl trimethyl ammonium bromide on the formation of both Ag/Ag 2 ZrO 3 nanocomposite and bare Ag 2 ZrO 3 has been studied. As-synthesized Ag/Ag 2 ZrO 3 and Ag 2 ZrO 3 have been further confirmed by using XRD, FESEM, HRTEM, and XPS analysis. The structural and morphological analysis of the Ag/Ag 2 ZrO 3 nanocomposite confirmed the existence of the metallic Ag in a mixed-phase on the surface of the Ag 2 ZrO 3 . The Ag/Ag 2 ZrO 3 nanocomposite exhibits almost 100% degradation of 6 ppm Methylene Blue dye in just 60 min (6.9E-2 min −1 ) in comparison to bare Ag 2 ZrO 3 . Furthermore, • OH is found to be the most reactive species responsible for the degradation of MB in case of Ag/Ag 2 ZrO 3 photocatalyst, while • O 2 − is pre dominant reactive species in the case of bare Ag 2 ZrO 3 . Both catalysts were found to be chemically stable with retention of photocatalytic efficiency even up to the six photocatalytic cycles.

Tuning Dehalogenative Coupling of Br2Py on Bimetallic Templates.

Considerable attention has been paid to on-surface Ullmann coupling during the past decade owing to the feasible synthesis of artificial nanostructures. While previous reports mainly concentrated on coupling reactions on single-metal-atom surfaces, herein we present the Ullmann coupling of 2,7-dibromopyrene (Br2Py) on bimetallic surfaces, Bi-Ag(111) and Bi-Au(111), respectively, with scanning tunneling microscopy (STM) and X-ray photoemission spectroscopy (XPS). On the Bi-decorated Ag(111), self-assembly of intact Br2Py is realized due to the reduced activity at the interface. Subsequent annealing promotes the dehalogenation of Br2Py on Bi-Ag(111), while Bi adatoms do not bring any visible influence on coupling reactions. Furthermore, post-deposition of Bi onto preassembled nanostructures on Ag(111) immediately initiates the Ullmann coupling by inducing more Ag adatoms available on the surface, while stepwise annealing afterward leads to complete polymerization and formation of covalent chains with lateral displacement compared to that on the bare Ag(111), probably due to the space hindrance and confinement. For Bi-Au(111) with the modified reconstruction, higher-temperature annealing is required to trigger Ullmann coupling compared to that on Au(111). The exception is that the C-C coupling reaction remains impervious to Bi adatoms, and recovery of the Bi-Au reconstruction is realized after intensive annealing. In principle, bimetallic surfaces herein present intriguing behavior toward the controllable Ullmann coupling, and this report might provide different insights into the comprehensive atomistic elucidation of reaction mechanisms as well as the design of a new platform to effectively regulate Ullmann coupling.