Ag Electrodes Research Articles

“Electrochemical reduction of HMF to synthesize added value compounds using CuAg electrodes”

In biorefining, Green electrochemistry offers an intelligent approach to produce valuable chemicals that are not derived from fossil fuels. In this study, we demonstrate the electrochemical reduction of 5-hydroxymethylfurfural (HMF), a biomass-derived compound, into 2,5-bis-hydroxymethylfuran (BHMF), which serves as a fundamental component in the polymer industry. This reaction was performed using Cu and Ag electrodes, but a better performance was obtained by combining the properties of the two metals in Ag decorated Cu foils. Additionally, by means of Impedance Spectroscopy IS we could uncover that the incorporation of Ag onto Cu electrodes not only increases the active area of the electrodes but also improves both the HMF adsorption on Cu and the catalytic properties of Ag. This synergistic effect leads to a more efficient reduction of HMF. Nonetheless, the diffusion of reactive species imposes a constraint on the increase in current. Finally, the observed inverted hysteresis in the cyclic voltammetry is attributed to variations in the amount of HMF adsorbed on the electrode surface during the forward and reverse directions of the cyclic voltammetry. Unlike other systems such as solar cells, where this effect is linked to the presence of a low frequency inductive behavior which, in this case, plays a negligible role.

Wearable and Wavelength-Tunable Near-Infrared Organic Light-Emitting Diodes for Biomedical Applications.

Near-infrared organic light-emitting diodes (NIR OLEDs) have significant potential for wearable phototherapeutic applications because of the unique properties of the OLEDs, including their free-form electronics and the excellent biomedical effects of NIR emission. In spite of their tremendous promise, given that the majority of NIR OLEDs in previous research have relied on the utilization of an intrinsically brittle indium tin oxide (ITO) electrode, their practicality in the field of wearable electronics is inherently constrained. Here, we report wearable and wavelength-tunable NIR OLEDs that employ a high-performance NIR emitter and an innovative architecture by replacing the ITO with a silver (Ag) electrode. The NIR OLEDs permit wavelength tuning of emissions from 700 to 800 nm and afford stable operation even under repeated bending conditions. The NIR OLEDs provide a lowered device temperature of 37.5 °C even during continuous operation under several emission intensities. In vitro experiments were performed with freshly fabricated NIR OLEDs. The outcomes were evaluated against experimental results performed using the same procedure utilizing blue, green, and red OLEDs. When exposed to NIR light irradiation, the promoting effect of cell proliferation surpassed the proliferative responses observed under the influence of visible light irradiation. The proliferation effect of human hair follicle dermal papilla cells is clearly related to the irradiation wavelength and time, thus underscoring the potential of wavelength-tunable NIR OLEDs for efficacious phototherapy. This work will open novel avenues for wearable NIR OLEDs in the field of biomedical application.

Fabrication of lead-free perovskite MASnBrI2 nanocrystals-embedded polymer composites for flexible strain sensors

In this work, the flexible piezoresistive films were synthesized through in-situ dispersing perovskite MASnBrI2 nanocrystals (NCs) into the elastic thermoplastic polyurethanes (TPU) substrate. Then, the flexible piezoresistive sensors were fabricated by sandwiching the NCs/TPU nanocomposite layer between interdigitated Ag electrodes. The piezoresistive behavior was attributed to the perovskite NCs which were distributed uniformly inside the TPU film. Specifically, it manifests as the change in electron cloud density of perovskite NCs under a pressure. The sensor made with a NCs/TPU composite membrane shows a pressure sensitivity of 0.796 kPa−1 over a wide linear range of 0∼0.7 kPa, an ultralow detect limitation of 0.2 Pa, a rapid response/recover time of 400 ms/370 ms and a good bending ability (90°). Additionally, the strain sensor also shows excellent performance in detecting the respiratory airflow, wrist pulse and finger joint curvature. We believe that this work might open up new opportunities for flexible strain sensors in the areas such as health monitoring, human-computer interaction, and smart electronic wearables.

Insight into the Role of Entropy in Promoting Electrochemical CO2 Reduction by Imidazolium Cations.

The electroreduction of CO2 plays an important role in achieving a net-zero carbon economy. Imidazolium cations can be used to enhance the rate of CO2 reduction reactions, but the origin of this promotion remains poorly understood. In this work, we show that in the presence of 1-ethyl-3-methylimidazolium (EMIM+), CO2 reduction on Ag electrodes occurs with an apparent activation energy near zero, while the applied potential influences the rate through the pre-exponential factor. Our findings suggest that the CO2 reduction rate is controlled by the initial state entropy, which depends on the applied potential through the organization of cations at the electrochemical interface. Further characterization shows that the C2-proton of EMIM+ is consumed during the reaction, leading to the collapse of the cation organization and a decrease in the catalytic performance. Our results have important implications for understanding the effect of potential on reaction rates, as they indicate that the common picture based on vibrational activation of electron transfer reactions is insufficient for describing the impact of potential in complex systems, such as CO2 reduction in the presence of imidazolium cations.

Maskless fabrication of quasi-omnidirectional V-groove solar cells using an alkaline solution-based method

Silicon passivated emitter and rear contact (PERC) solar cells with V-groove texture were fabricated using maskless alkaline solution etching with in-house developed additive. Compared with the traditional pyramid texture, the V-groove texture possesses superior effective minority carrier lifetime, enhanced p–n junction quality and better applied filling factor (FF). In addition, a V-groove texture can greatly reduce the shading area and edge damage of front Ag electrodes when the V-groove direction is parallel to the gridline electrodes. Due to these factors, the V-groove solar cells have a higher efficiency (21.78%) than pyramid solar cells (21.62%). Interestingly, external quantum efficiency (EQE) and reflectance of the V-groove solar cells exhibit a slight decrease when the incident light angle (θ) is increased from 0° to 75°, which confirms the excellent quasi omnidirectionality of the V-groove solar cells. The proposed V-groove solar cell design shows a 2.84% relative enhancement of energy output over traditional pyramid solar cells.

Self-Powered Photodetector Based on Ag/CH3NH3PbI3/C Asymmetric Dual-Terminal Device.

CH3NH3PbI3 is capable of exhibiting a superior photoresponse to visible light, but its self-powered devices are typically formed through p-n junctions. In this study, we fabricated a Ag/CH3NH3PbI3/C dual-terminal asymmetric electrode device using a single CH3NH3PbI3 perovskite micro/nanowire, enabling both the photoresponse and self-powered characteristics of CH3NH3PbI3 to visible light. Compared with traditional p-n junction devices, this simple device demonstrates enhanced interface photovoltaic effects by optimizing the combination of the Ag electrode with CH3NH3PbI3, resulting in superior self-powered characteristics. Under low bias voltage, the device achieves a significant on/off ratio of 103, with superior sensitivity and responsivity as well as a maximum rectification ratio of about 12. The photogenerated voltage and current reach approximately 0.8 V and 2 nA, respectively. This simple, compact, and self-powered asymmetric device exhibits great potential for applications in self-powered optoelectronics and wearable devices. This research provides a promising approach for recognizing and utilizing surface state effects in single nanoscale structures.

CATALASE AND PEROXIDASE BIOMIMETIC SENSOR BASED ON Ag-ELECTRODE

Research has been carried out on the development of a biomimetic sensor of the catalase and peroxidase type to determine trace amounts of peroxide hydrogen and low concentrations of ethyl alcohol in an aqueous solution. By potentiometric research, the physicochemical feature of the catalase and peroxidase biomimetic sensor was studied, the transducer of which was Ag. Rapid and accurate determination of hydrogen peroxide is very important, but no less important side of this issue is associated with the determination of trace amounts of C2H5OH in aqueous media of various origins. The need to develop express methods for determining the concentration of C2H5OH in aqueous solutions follows from the requirements for the quality of wine and alcohol products. As you know, the taste and drinking qualities of the product depend on the ratio of methyl and ethyl alcohols. In this work, biomimetic sensors of the catalase and peroxidase types based on an Ag electrode were developed for determining trace amounts of hydrogen peroxide and ethanol. Biomimetic sensors of the catalase and peroxidase types based on an Ag electrode have been developed for the determination of microquantities of hydrogen peroxide and ethyl alcohol. The applicability of a biomimetic sensor for determining trace concentrations of hydrogen peroxide, as well as for determining microquantities of ethyl alcohol in an aqueous solution with a low detection limit, high sensitivity, wide recognition range, high stability, and repeated use, is shown. The developed and synthesized biomimetic sensor of the catalase and peroxidase types based on TPhPFe3+/Al2O3/Ag have high sensitivity, stability, and do not lose their activity for a long time

A Biochemical Corrosion Monitoring Sensor with a Silver/Carbon Comb Structure for the Detection of Living Escherichia coli.

For the detection and monitoring of live bacteria, we propose a biochemical corrosion monitoring (BCM) sensor that measures galvanic current by using a Ag/C sensor comprising silver and carbon comb electrodes. The deposition of an Escherichia coli suspension containing an LB liquid medium on the Ag/C sensor increased the galvanic current. The time required for the current to reach 20 nA is defined as T20. T20 tends to decrease as the initial number of E. coli in the E. coli solution increases. A linear relationship was obtained between the logarithm of the E. coli count and T20 in a bacterial count range of 1-108 cfu/mL under culture conditions in which the growth rate of the bacteria was constant. Hence, the number of live E. coli could be determined from T20. Ag2S precipitation was observed on the surface of the Ag electrode of the Ag/C sensor, where an increase in the current was observed. This generation of galvanic current was attributed to the reaction between a small amount of free H2S metabolized by E. coli in the bacterial solution during its growth process and Ag-the sensor anode. The Ag/C sensor can detect a free H2S concentration of 0.041 μM in the E. coli solution. This novel biochemical sensor can monitor the growth behavior of living organisms without damaging them.

Silver nanoparticles catalyzed electrochemical hydrodechlorination of dichloromethane to methane in N,N-Dimethylformamide using water as hydrogen donor

Silver nanoparticles (Ag NPs) were modified on Ag electrode in situ using the electrochemical redox method. The electrochemical hydrodechlorination (EHDC) performance of Ag NPs in N,N-Dimethylformamide (DMF) for a representative chlorinated volatile organic compound, dichloromethane (DCM), was studied. The results revealed that a large number of Ag NPs (∼7 nm) were successfully deposited on the surface of Ag electrode. Be benefit to Nano effect, Ag NPs exhibited higher EHDC catalytic activity than bulk Ag and inhibited H2 evolution. Under the catalysis of Ag NPs, the dechlorination of two Cl atoms on DCM was changed from synchronous dechlorination to asynchronous dechlorination. The EHDC efficiency of DCM in the three DMFs ranked from high to low as follows: weakly alkaline > Neutral > Weakly acidic. DCM at concentrations of 10–150 mM can be hydrodechlorinated to methane with ≥90% yield and ≥35% current efficiency.

Effects of different interface on the stability of hybrid heterojunction solar cells

With the rapid increase in efficiency of organic-inorganic hybrid solar cells of Si-poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate) (PEDOT:PSS), their poor stability has become an important factor limiting its further development. Here, we demonstrate that the moisture in the air is the main cause for the performance degradation of the hybrid heterojunction solar cells (HHSCs) and innovatively discovered the effect of the Ag electrodes on the degradation of HHSCs. When exposed to air, the growth of the thin oxide layer on the interface of n-Si/PEDOT:PSS and the formation of silver sulfide (Ag2S) on the Ag/PEDOT:PSS interface together caused the increase in the series resistance (Rs) of the HHSCs. The increase in Rs decreases the fill factor (FF) of the HHSCs and thus leads to the degradation of the cell performance.

Improvement of Performance of Cu2ZnSn(S, Se)4 Solar Cells by Low‐Temperature Annealing of B‐Doped CdS

It is known that high carrier recombination at the p–n junction interface and low carrier separation ability (CSA) are two main problems resulting in low power conversion efficiency (PCE) of the Cu2ZnSn(S,Se)4 (CZTSSe) solar cell. To resolve these problems, one CZTSSe solar cell is prepared through substituting B‐doped CdS for CdS in a solar cell with the conventional structure of Ag/ITO/ZnO/CdS/CZTSSe/Mo/SLG and annealing B‐doped CdS/CZTSSe/Mo/SLG prior to deposition of ZnO, ITO, and Ag electrode. By optimizing the B doping content in the CdS and annealing temperature and time of the B‐doped CdS/CZTSSe, lattice mismatch between CdS and CZTSSe is decreased and width of depletion region is increased, leading to reduction in interfacial recombination, enhancement in CSA and intensity of incident light passing through the B‐doped CdS, and so increase in PCE from 7.89% of CZTSSe solar cell using CdS as buffer layer to 10.62%. A mechanism of the increment of the PCE induced by B doping and annealing is suggested. This work proposes a method of increasing PCE of CZTSSe solar cell and advances a deeper understanding of the mechanisms behind various parameters in CZTSSe solar cells through theoretical analysis and calculations.

Influences of Metal Electrodes on Stability of Non‐Fullerene Acceptor‐Based Organic Photovoltaics

AbstractUnderstanding chemical degradation at the interface between different layers in an organic photovoltaic device (OPV) is crucial to improving the long‐term stability of OPVs. Herein, molecular‐level insights are provided into the impact of different metal top electrodes on the interfacial morphology and stability of photoactive layers in PM6:Y6 bulk‐heterojunction (BHJ) OPVs. OPVs with an aluminum (Al) top electrode exhibit inferior stability compared to silver (Ag) electrode devices upon thermal annealing, whereby thermal stress induces the diffusion of both Al and Ag atoms to the PM6:Y6 BHJ layer. The diffused Al atoms cause surface recombination at the interface between the photoactive layer and an interlayer. Specifically, X‐ray photoelectron spectroscopy suggests the different local chemical environments of PM6 and Y6 moieties in PM6:Y6/Al‐contact devices. These results are corroborated by solid‐state nuclear magnetic resonance and electron paramagnetic resonance spectroscopy measurements, indicating the formation of ionic and organo‐metallic‐like species at the sub‐layers of the PM6:Y6 BHJ morphology, which are estimated to be less than 5 wt% of the PM6:Y6/Al blend. By comparison, the Ag atoms do not adversely affect PM6:Y6 BHJ morphology and the associated device physics. The investigation of reactive electrode‐BHJ interfaces by multiscale characterization techniques and device physics is expected to provide guidance to future interfacial engineering strategies to develop stable and efficient OPVs.

Sintering behavior, structural evolution, and dielectric properties of Li2+MgTiO4F microwave dielectric ceramics

Herein, the sintering behavior, structural evolution, microstructure, and dielectric properties of Li2+xMgTiO4Fx (0 ≤ x ≤ 5) ceramics were investigated. At x ≤ 0.75, Li2+xMgTiO4Fx ceramics formed a continuous solid solution with a cubic rock salt structure. Subsequently, a composite ceramic of Li2+xMgTiO4Fx and LiF was formed. It was found that the maximum mass percentage of LiF required to fully form a solid solution was between 11% and 13%. The Li2.75MgTiO4F0.75 exhibited the best dielectric properties: εr = 16.52, Q × f = 123,574 GHz, and τf = −18.11 ppm/°C. The substitution of F- for O2- resulted in a lower sintering temperature of 875 °C, which slightly suppressed the volatilization of Li, and thus optimized the dielectric properties. The decrease in lattice vibration damping behavior and the increase in electron cloud density resulted in lower dielectric losses. The reduction in molecular polarization rate led to a reduction in εr, and the increase in bond energy optimized τf. Good chemical compatibility with Ag electrode was demonstrated, indicating that Li2+xMgTiO4Fx ceramics have unlimited potential for LTCC applications.

Tailoring Ag Electron Donating Ability for Organohalide Reduction: A Bilayer Electrode Design.

Electrochemical reduction of organohalides provides a green approach in the reduction of environmental pollutants, the synthesis of new organic molecules, and many other applications. The presence of a catalytic electrode can make the process more energetically efficient. Ag is known to be a very good electrode for the reduction of a wide range of organohalides. Herein, we examine the elementary adsorption and reaction steps that occur on Ag and the changes that result from changes in the Ag-coated metal, strain in Ag, solvent, and substrate geometry. The results are used to develop an electrode design strategy that can possibly be used to further increase the catalytic activity of pure Ag electrodes. We have shown how epitaxially depositing one to three layers of Ag on catalytically inert or less active support metal can increase the surface electron donating ability, thus increasing the adsorption of organic halide and the catalytic activity. Many factors, such as molecular geometry, lattice mismatches, work function, and solvents, contribute to the adsorption of organic halide molecules over the bilayer electrode surface. To isolate and rank these factors, we examined three model organic halides, namely, halothane, bromobenzene (BrBz), and benzyl bromide (BzBr) adsorption on Ag/metal (metal = Au, Bi, Pt, and Ti) bilayer electrodes in both vacuum and acetonitrile (ACN) solvent. The different metal supports offer a range of lattice mismatches and work function differences with Ag. Our calculations show that the surface of Ag becomes more electron donating and accessible to adsorption when it forms a bilayer with Ti as it has a lower work function and almost zero lattice mismatch with Ag. We believe this study will help to increase the electron donating ability of the Ag surface by choosing the right metal support, which in turn can improve the catalytic activity of the working electrode.

Lysine based dipeptides-molecular rectifiers with very high rectification ratio and their application towards designing logic gates

In this research paper, we have enquired the dipeptides (i.e., smallest peptides) consisting of oppositely charged amino acids namely, Lysine-Aspartic and Lysine-Glutamic, where l-Lysine is positively charged, and both L-Aspartic and L-Glutamic are negatively charged amino acids. The l-Glutamic acid has only one extra CH2 chain as compared with l-Aspartic acid. These two dipeptides are stringed to Au, Ag and Cu electrodes, to form molecular devices. Distinct parameters including conductance, Homo-Lumo gap, dipole moment, current-voltage characteristics are intrigued using NEGF-DFT technique. Au-Lysine-Aspartic-Au offers the negative differential resistance regime with the highest peak-to-valley current ratio of 28.79. Lysine-Aspartic with Cu electrodes and Lysine-Glutamic with Au electrodes offers the highest rectification ratio of 146.96 and 34.31 respectively, as compared with other electrodes. Lysine-Aspartic based dipeptides offer higher rectification ratio as compared with Lysine-Glutamic based dipeptides. Moreover, these two dipeptides offer opposite correlation between dipole moment, coupling strength and switching regimes. The reason behind rectification ratio and negative differential resistance is elaborated using transmission spectra, molecular projected self-Hamiltonian states and transmission pathway. The OR, AND and XOR logic gates are proposed using switching regimes of Au-Lysine-Aspartic-Au. We have also detected the thermal stability of one of the heterostructure using ab initio molecular dynamics simulation.

Bond characteristics, microstructure, and microwave dielectric properties of Bi2O3–ZnO–B2O3 glass-ceramics with Li2O substitution

The effect of Li2O substitution on the sintering behavior, lattice structure, microstructure, and microwave dielectric properties of ZnO–B2O3–Bi2O3 glass-ceramics was studied by various amounts of Li2O to substitute ZnO. The substitution of Li2O decreases the glass network connectivity and thus decreases the sintering temperature of the glass. In the sintered glass-ceramics, the substitution of 0.2 mol% Li2O leads to the most significant lattice activation resulting in the glass-ceramic exhibiting the smallest cell volume of Zn3B2O6 crystal and the microstructure with fine and uniform grains. The P–V-L theory is innovatively applied to glass-ceramic materials to characterize the variation in bond characteristics caused by lattice activation and it indicates that the 0.2 mol% Li2O substitution decreases the Zn–O bond ionicity and increases the lattice energy of the B–O bond, in the Zn3B2O6 crystalline phase. The refinement of microstructure and the optimization of bond characteristics improve the microwave dielectric properties of glass-ceramics. The glass-ceramic with 0.2 mol% Li2O substitution sintered at 620 °C for 5 h exhibits excellent microwave dielectric properties of εr ∼5.05, Q×f ∼15,383 GHz, τf ∼ −6 ppm/°C and good chemical compatibility with Ag or Al electrodes, which is a favorable candidate for application in ULTCC substrate materials.

Flexible Screen-Printed Amperometric Sensors Functionalized With Spray-Coated Carbon Nanotubes and Electrodeposited Cu Nanoclusters for Nitrate Detection

In this work, we present a novel, sensitive, easy-to-fabricate, flexible amperometric sensor constituted by screen-printed silver (Ag) electrodes functionalized with a copper (Cu) film electrodeposited on top of a spray coated network of single-walled carbon nanotubes (SWCNTs). The Cu/SWCNTs/Ag electrode showed excellent catalytic activity towards the electro-reduction of nitrate ions at neutral pH with a significant increase in cathodic peak currents in comparison with the electrode without SWCNTs (Cu/Ag). The developed Cu/SWCNTs/Ag sensor showed a wide linear detection range from 0.5 μM to 6.0 mM (0.31 mg/l to 372.02 mg/l) with good sensitivity (18.39 μA/mM) and a calculated limit of detection (LOD) of 0.166 nM (10.29 μg/l). It also showed a good selectivity (maximum standard deviation (SD) was 3.25 μA) towards different interfering ions (Fe2+, Na+, Cu2+, SO42-, CH3COO-, Cl-, NO2- and HCO3-), as well as good reproducibility, mechanical durability, time and temperature stability. In real sample analysis (tap and river water), the sensor exhibited good agreement with the compared outcome of high-performance liquid chromatography (HPLC) measurements, proving to be a promising analytical tool for the detection of nitrate in water.

Solution Processed Semi-Transparent Organic Solar Cells Over 50% Visible Transmittance Enabled by Silver Nanowire Electrode with Sandwich Structure.

Photovoltaic windows with easy installation for the power supply of household appliances have long been a desire of energy researchers. However, due to the lack of top electrodes that offer both high transparency and low sheet resistance, the development of high-transparency photovoltaic windows for indoor lighting scenarios has lagged significantly behind photovoltaic windows where privacy issues are involved. Addressing this issue, this work develops a solution-processable transparent top electrode using sandwich structure silver nanowires, realizing high transparency in semi-transparent organic solar cells. The wettability and conducting properties of the electrode are improved by a modified hole-transport layer named HP. The semi-transparent solar cell exhibits good see-through properties at a high average visible transmittance of 50.8%, with power conversion efficiency of 7.34%, and light utilization efficiency of 3.73%, which is the highest without optical modulations. Moreover, flexible devices based on the above-mentioned architecture also show excellent mechanical tolerance compared with Ag electrode counterparts, which retains 94.5% of their original efficiency after 1500 bending cycles. This work provides a valuable approach for fabricating solution-processed high transparency organic solar cells, which is essential in future applications in building integrated photovoltaics.

Cobalt(II)-complex modified Ag electrode for efficient and selective electrochemical reduction of CO2 to CO

Electrochemical conversion of CO2 into CO, powered by renewable electricity, offers one means to address the need for the storage of intermittent renewable energy. However, it is challenging because the competing HER is hard to avoid, which significantly compromises the selectivity to CO and reduces the efficiency of CO2RR devices. This study reports a cooperative catalyst design of metal–molecule catalyst interfaces with the goal of high local concentration of CO2 and stabilizing the intermediate, which improves the electrosynthesis of CO. The strategy is implemented by functionalizing the silver surface with cobalt (II)-complexes to promote the selective electrolysis of CO2 to CO. We report a CO2-to-CO Faradaic efficiency of 98.5 % and a partial current density of 16.52 mA cm−2 at − 1.1 V vs. RHE. Mechanism studies reveal that the catalytic performance of the Ag/Co(bpy)32+ correlates with the metal–molecule interaction, which provide new opportunities for construction and design of high-efficient catalysts toward CO2 reduction.

Co-sputtered V2O5–TiN composite on Ag-network current collector for high-performance flexible transparent thin-film supercapacitors

Next-generation wearables require extremely capable electrochemical energy-storage devices that exhibit improved performance with high flexibility and transparency. Herein, we present a highly flexible and transparent electrochemical thin-film supercapacitor electrode fabricated by co-sputtering V2O5 and TiN on an Ag-network-based current collector. The electrodes' physical properties, optical properties, and structural morphologies are studied using X-ray diffraction, UV–visible spectroscopy, and scanning electron microscopy, respectively. A symmetric device is fabricated using V2O5 and TiN on an Ag network, and the TiN sputter power is varied to optimize the performance. The device performance of the co-sputtered electrodes at various composition ratios is studied. The optimized V2O5–TiN (200−40)/Ag electrode device with pseudocapacitive behavior delivers an excellent areal specific capacitance of 98.66 mF cm–2 at a current density of 4 mA cm–2 with a charge retention of 90.12 % after 6000 cycles. The V2O5–TiN (200−40)/Ag electrode device outperforms other reported electrodes, with an energy density and power density of 30.83 μWh cm–2 and 2999.67 μW cm–2, respectively, and excellent mechanical stability.