Electrode Separation Distance Research Articles

Continuous caustic aqueous phase electrochemical reforming (CAPER) of ethanol for producing compressed hydrogen

Caustic Aqueous Phase Electrochemical Reforming (CAPER) of ethanol produces pure compressed H2 at lower voltages, temperatures, and energy requirements than conventional electrolysis, while capturing carbonaceous products. The CAPER flow reactor consists of stainless steel endplates, stainless steel current collectors, and a Teflon flow field. The electrodes are prepared using commercial palladium nanoparticles on carbon support for the anode and platinum nanoparticles on carbon support for the cathode. The catalyst metal loading was 1 mg cm–2 on a 10 cm2 carbon cloth for both electrodes. Our CAPER reactor produces pure H2 at 80 bar and 80 °C applying voltages at ≤0.5 V. The only gas-phase product detected was H2 and any carbonaceous products were contained in the liquid phase. The H2 was produced with 97 ± 4% faradaic efficiency. Operating at smaller electrode separation distances (4 mm) and 80 °C increased the current density. The highest lower heating value efficiency achieved was 28% at a flow rate of 0.05 mL min–1 and an applied voltage of 0.5 V. The compressed H2 was produced at ≤20 kWh kg–1, which is much lower than electrolysis systems that require upwards of 50 kWh kg–1.

Microfluidic Flow-By reactors minimize energy requirements of electrochemical water treatment without adding supporting electrolytes

While electrode material advances show how electrochemical processes can degrade wide range of environmental pollutants, less research exists on how to lower energy requirements for electrolysis through innovation in reactor geometry that control mass transfer. Microfluidic devices with high electrode surface area to solution volume ratios offer unique insights since they can minimize mass transfer limitations in electrochemical reactors and decrease the energy requirements. Shortening interelectrode distances hold promise to overcome charge transfer limitations, which otherwise requires electrolytes addition for low conductivity drinking waters. To examine the interconnected effects of electrode separation distances and solute concentrations on mass transport and energy efficiency, electrochemical treatment using a model water pollutant (nitrite ion) was evaluated in a flow-by microelectromechanical system (MEMS) reactor where the electrodes were ∼ 40 µm apart in microfluidic reactors. The performance was compared to conventional completely-mixed batch reactors with interelectrode distance of 1 cm. The microfluidic reactors showed decrease of electrical energy per order (EE/O) in one order of magnitude with the ability to degrade contaminants with concentrations as low as 5 mg/L without increasing the energy consumption with the absence of supporting electrolytes. This paper presents a promising approach to study and ultimately develop cost-effective electrochemical technologies by optimizing electrode separation distances, instead of increasing salinity which is often required to achieve sufficient conductivity in water but is counter producing low-salt potable drinking water.

Mechanically Tuned Thermopower of Single‐Molecule Junctions

AbstractIn this paper, the tuning of the thermopower with single‐molecule junctions of fullerene (C60), 4,4′‐bipyridine (BPY), and p‐phenylenediamine (PPD) using scanning tunneling microscopy (STM)‐based break junction technique is demonstrated. Single‐molecule junctions are prepared in a nanogap between a Au‐STM tip and a Au(111) electrode. Upon applying a temperature difference across the junction, a thermoelectric voltage is generated across it. By mechanically controlling the tip–electrode separation distance, the thermoelectric voltage of the junction is tuned. The absolute value of the thermopower decreases with decreasing tip–electrode separation distance for BPY and PPD, while it increases for C60. Atomistic simulations of the junction illustrate how this arises from shifts in the conduction orbital energies induced by the mechanical compression of the junctions.

Operando Monitoring of Local pH Value Changes at the Carbon Electrode Surface in Neutral Sulfate-Based Aqueous Electrochemical Capacitors.

The operando monitoring of pH during the charging and discharging of an electrochemical capacitor in an aqueous neutral salt solution is presented. Proper knowledge of transient and limiting pH values allows for a better understanding of the phenomena that take place during capacitor operation. It also enables the proper assignment of the reaction potentials responsible for water decomposition. It is shown that the pH inside the capacitor is strongly potential-dependent and different for individual electrodes; therefore, the values of the evolution potentials of hydrogen and oxygen cannot be precisely calculated based only on the initial pH of the electrolyte. The operando measurements indicate that the pH at the positive electrode reaches 4, while at the negative electrode, it is 8.5, which in theory could shift the theoretical operating voltage well beyond 1.23 V. On the other hand, high voltage cannot be easily maintained since the electrolyte of both electrode vicinities is subjected to mixing. Operando gas monitoring measurements show that the evolution of electrolysis byproducts occurs even below the theoretical decomposition voltage. These reactions are important in maintaining a voltage-advantaged pH difference within the cell. At the same time, the electrochemical quartz crystal microbalance (EQCM) measurements indicated that the ions governing the pH (OH–) that initially accumulated in the vicinity of the positive electrode enter the carbon porosity, losing their pH-governing abilities. pH fluctuations in the cell are important and play a vital role in the description of its performance during the cyclability at a given voltage. This is especially noticeable in cell floating at 1.3 V, where the pH difference between electrodes is the highest (6 units). The increase of the electrode separation distance acts similarly to the introduction of a semipermeable membrane toward the increase of the capacitor cycle life. During floating at 1.6 V, where the pH difference is not as high anymore (4 units), the influence of separation in terms of electrode stability, although present, is less notable.

Electrocoagulation As an Alternative Drinking Water Treatment to Decrease Calcium and Manganese from Groundwater: Ecuadorian Case Study

Only 37.2% of the rural population of the municipality of San Cristobal in the canton of Paute-Azuay received drinking water according to the population census carried out in 2010. Paute has 2794 inhabitants and this number is expected to grow to 3406 by 2041. Water analysis results published by the local authorities of Paute reported a high concentration of Ca2+ hardness, e.g. 442±32 mg/L of CaCO3 and a concentration of manganese of 0.97 mg/L in the groundwater catchment source. These results far exceed the concentrations suggested by the World Health Organization (WHO) for drinking water as hardness and Mn can affect the water distribution systems and the people health. Since levels under 100 mg/L of calcium hardness induce corrosion of the steel pipes of the plumbing systems, a concentration of Ca2+ ranging from 100 to 200 mg/L is recommended. On the other hand, levels of Ca2+ higher than 200 mg/L may cause scaling in the drinking water distribution systems. It is regulated that the level of Mn must be <0.4 mg/L due to the fact that this element can affect the nervous system.The aim of this work is to test the electrocoagulation process as an alternative water treatment to evaluate the removal of Ca2+ and Mn in water to design the reactor, considering technical, environmental, and socioeconomic criteria. The electrocoagulation process was performed under galvanostatic conditions in a single compartment electrochemical cell using a two-electrode setting (carbon steel) and filled with 150 mL of water coming from the sedimentation stage of the treatment plant. The experiments were performed under different current densities, pH, operating and sedimentation times using a batch process. The concentration of Ca2+ was measured by EDTA titrimetric method before and after the electrocoagulation process. In order to enhance the removal of Ca2+,Ca(OH)2 was added. Similarly, unstable parameters such as total dissolved solids, electrical conductivity, and pH were measured to assess their influence before and after the electrocoagulation process. In addition, chemical oxygen demand (COD) was measured to evaluate if additional chemicals are generated during the process. To estimate the amount of sludge generated, sedimentable solids were measured using the Imhoff cone. These results were used to design the electrocoagulation reactor. The experimental results showed that higher efficiencies are achieved in basic water (pH~8), using an applied current density of 9.56 mA/cm2 and operating and sedimentation time of 60 and 20 min respectively. Under these conditions, the efficiency of Ca2+ removal was 59.3%. It was observed that the sedimentation process did not strongly influence the efficiency of the process. The addition of 100 μL of Ca(OH)2 at 20% increases the Ca2 removal efficiency to 85% and the Mn removal efficiency was 97% under the same conditions.The electrical energy demand was calculated to be 1.13 kWh/m3, this energy consumption is associated with the dimensions for a tank with a flow rate of 11 m3/h. The dosage of Ca(OH)2 was calculated to ebe 0.13 Kg/m3 which is not linked to the reactor dimensions. No alteration in the COD concentration was registered and the generation of sludge was 2.2 times lower than the amount generated using a conventional flocculation process. Once the optimum conditions were obtained, the dimensions of the reactor were established, the diameter of the electrocoagulation reactor is 3.36 m which is 9 times of the electrode diameter, while the height of the reactor is 2 times the height of the electrode, e.g. 1.25 m. The electrode separation distance must not be longer than 0.35 times the diameter of the reactor. Electrocoagulation is a more sustainable process since it produces the coagulant in-situ with low production of sludge mostly biodegradable. In this study the removal of Ca2+ and Mn was optimized obtaining efficiencies >85% where the addition of Ca(OH)2 enhances the electrocoagulation process. The low energy consumption in the electrocoagulation reduces the operational costs of this treatment alternative.

DC AFCI 성능평가를 위한 UL1699B 표준에 따른 시험설비 구축

This paper deals with the implementation of test facility for DC AFCI(Arc fault circuit interrupter) series arc detection performance evaluation based on UL1699B standard. The implemented test facility consists of DC source, decoupling network, line impedance, inverter and arc generator. The developed electric arc generator enables precise control for spacing between the arc electrodes. Implemented test facility complies with a single full string model presented on UL1699B. Mode 1 to Mode 4 are presented as test modes. The test conditions of inverter voltage, current, minimum arc current conditions, electrode separation speed and distance are satisfied by implemented test facility when arcing occurred in all test modes. Also the series arc detection performance evaluation result of DC AFCI under the mode 1 condition is presented. The implemented test facility is expected to be applied to the series arc detection performance evaluation of DC AFCI under all test mode conditions.

Characterization of Atmospheric-Pressure DC-Glow Discharge in Contact with Liquid with a Miniature Argon Flow

Atmospheric pressure dc glow discharges in contact with liquid with a miniature argon flow were created between a needle cathode and an electrolyte anode (NaCl solution) in the open air. The effect of argon flow in stabilizing the obtained discharge was explored. Electric characterization of the discharge was studied for electrode separation range from 1 to 12 mm at atmospheric pressure. The electrical characterization of the discharge revealed that the obtained Paschen curve showed a bi-straight line for the relation between the gas breakdown voltage and the product of the gas pressure 𝑝 with the electrode separation distance 𝑑. The current-voltage characteristics of the discharge revealed that the discharge was operated in the normal glow mode. Optical characterization of the discharge showed that the discharge was strongly non-equilibrium, which is suitable for electrochemistry applications such as synthesizing magnetic nanoparticles from the iron electrode. Proposed chemical reaction routes for different electrochemical applications of DC glow discharge in contact with the liquid electrode were discussed.

POTENCIAL ELÉCTRICO ENTRE ELECTRODOS PLANOS NO PARALELOS – SIMULACIÓN DE UNA CELDA UTILIZADA CON TOMATE

The equipotential lines of the field generated by the cell used in dielectric measurements of whole fruit tomato are plotted. This cell consists of two inclined electrodes, at inverse potentials, and is an adaptation made in the Dielectric Laboratory of the cell used by Varlan-Sansen. To obtain the graphs, the Laplace equation was solved by finite differences and a program in Fortran language was written, which performs the calculations by numerical iteration. The field generated by the cell at different electrode separation distances was analyzed.

Assessment of triboelectricity in colossal-surface-area-lanthanum oxide nanocrystals synthesized via low-temperature hydrothermal process

Triboelectric nanogenerators (TENGs) have marked their applications in various fields, most importantly, in medical devices. The electrical output of the TENGs mainly concentrated on parameters such as electrode separation distance, applied mechanical pressure, surface charge density, and overlapping surface area. The surface area of the active layer in TENGs plays a crucial role. Given this, the present contribution is the first report on the utilization of lanthanum oxide (La2O3) as an active material with a large surface area (~ 72.33 m2/g) in TENGs. The nanocrystals of La2O3 have been successfully embedded into TENGs architecture through a high-quality screen-printed film with a Teflon-counter surface. The in-house test-rig of TENGs resulted in an output open-circuit voltage of 120 V and a short-circuit current of 23.7 μA. Further, the maximum power density is 7.125 W/m2 at an external load resistance of 30 MΩ. These results suggest that La2O3 is a suitable contender in various self-powered devices.

Multiphysics simulation of phase field interface development and geomechanical deformation in radio frequency heating of oil shale

A novel multiphysics finite element framework, developed to numerically model in-situ pyrolysis of oil shale by radio frequency heating in a two-dimensional (2D) domain, is extended to include deformation analysis of the target formation and adjacent regions as a result of dielectric heating. This framework is constructed by explicitly coupling equations describing thermal, phase field front tracking, mechanical deformation and electromagnetics (TPME) to track the conversion of high yield oil shale to liquid oil. The finite element method is used to model heat generation by the conversion of electromagnetic energy in the formation then the solid-liquid conversion interface is tracked by the Allen-Cahn phase field method. The objective of this work is to analyze the evolution of the conversion interface and the subsequent mechanical deformation of the target formation by evaluating disparate geologic model descriptions to capture the anticipated subsurface behavior. These geologic models possess variations in complexity so that the appropriate level of detail in the geological model description can be assessed for further TPME simulation studies of radio frequency heating. The evaluated geologic models include those which are comprised of: heterogeneous or homogeneous high yield kerogen-rich properties in addition to the inclusion or omission of under- and overburden surrounding the target formation at varying electrode separation distances and applied electromagnetic frequencies. Parameterization of the numerical model was performed following characteristics of the Green River oil shale. Results show the variation in conversion interface of solid kerogen to liquid oil by way of interface arrival times at domain boundaries as well as the extent of formation deformation under the disparate geological model descriptions. Based on these results oil shale conversion timelines are compared and highlight the need to include mechanical deformation analysis of the target formation, including a kerogen-poor under- and overburden, in the numerical modeling of radio frequency heating as a process of oil shale in-situ pyrolysis.

Experimental studies on cold fusion nuclear reaction process using different electrodes

The present work focus on introducing different electrodes and electrolytes to trigger the cold fusion nuclear reaction process and thereby validating the feasibility and reproducibility of the reaction rate and excess heat density produced. Single cell calorimetric method has been used for the experiment. The reaction rate and excess enthalpy generation was found to be depending on certain parameters and these parameters, when controlled accurately, can ignite the fusion process with considerably high steam generation. A maximum temperature of 120 °C is observed from the experiment with tungsten as cathode, stainless steel as anode and 10 g KOH as electrolytic solution. NaOH and Na2CO3 as electrolytes, tabulated a peak temperature of 110 °C and 103 °C respectively. The present work could be a base to conduct experiments by varying the electrode materials, separation distance, electrolytic solution and voltage density.

Diversity of neurogenic smooth muscle electrical rhythmicity in mouse proximal colon.

The mechanisms underlying electrical rhythmicity in smooth muscle of the proximal colon are incompletely understood. Our aim was to identify patterns of electrical rhythmicity in smooth muscle of the proximal region of isolated whole mouse colon and characterize their mechanisms of origin. Two independent extracellular recording electrodes were used to record the patterns of electrical activity in smooth muscle of the proximal region of whole isolated mouse colon. Cross-correlation analysis was used to quantify spatial coordination of these electrical activities over increasing electrode separation distances. Four distinct neurogenic patterns of electrical rhythmicity were identified in smooth muscle of the proximal colon, three of which have not been identified and consisted of bursts of rhythmic action potentials at 1-2 Hz that were abolished by hexamethonium. These neurogenic patterns of electrical rhythmicity in smooth muscle were spatially and temporally synchronized over large separation distances (≥2 mm rosto-caudal axis). Myogenic slow waves could be recorded from the same preparations, but they showed poor spatial and temporal coordination over even short distances (≤1 mm rostro-caudal axis). It is not commonly thought that electrical rhythmicity in gastrointestinal smooth muscle is dependent upon the enteric nervous system. Here, we identified neurogenic patterns of electrical rhythmicity in smooth muscle of the proximal region of isolated mouse colon, which are dependent on synaptic transmission in the enteric nervous system. If the whole colon is studied in vitro, recordings can preserve novel neurogenic patterns of electrical rhythmicity in smooth muscle.NEW & NOTEWORTHY Previously, it has not often been thought that electrical rhythmicity in smooth muscle of the gastrointestinal tract is dependent upon the enteric nervous system. We identified patterns of electrical rhythmicity in smooth muscle of the mouse proximal colon that were abolished by hexamethonium and involved the temporal synchronization of smooth muscle membrane potential over large spatial fields. We reveal different patterns of electrical rhythmicity in colonic smooth muscle that are dependent on the ENS.

The impact of cathode surface roughness and multiple breakdown events on microscale gas breakdown at atmospheric pressure

Gas breakdown is typically driven by Townsend avalanche and predicted mathematically by Paschen’s law (PL). Gas breakdown deviates from PL at microscale due to field emission, which depends critically on electrode condition; however, understanding of the impact of initial electrode surface roughness and multiple breakdown events on breakdown voltage is incomplete. This paper assesses the variation of breakdown voltage for a pin-to-plate electrode setup in air at atmospheric pressure for gap distances of 1 ± 0.5 μm, 5 ± 0.5 μm, and 10 ± 0.5 μm with different surface roughnesses. Breakdown voltage generally increases with increasing gap distance and decreasing surface roughness for a single breakdown event; however, the breakdown voltage after ten breakdown events does not depend on initial gap distance. Atomic force microscopy and optical microscopy show that multiple discharges create circular craters on the flat cathode up to 40 μm deep, with more pronounced craters created at smaller gap sizes and greater cathode surface roughness. The resulting effective gap distances (deff, the sum of cathode placement distance and crater depth) for subsequent breakdown events are similar to those of the initially larger gap distances. Moreover, deff becomes sufficiently large to exceed the Meek criterion for streamer formation, indicating a potential for breakdown mechanisms to change from field emission to Townsend avalanche to streamer formation for a single electrode separation distance. The resulting impact of this change in the breakdown mechanism could have significant implications for ensuring consistent microdevice operation.

Effect of poling orientation on piezoelectric materials operating in longitudinal mode

This study puts forward the consequence of poling direction on piezoelectric materials operating in longitudinal (d33) mode. It has been mathematically presented that piezoelectric strain coefficients get altered due to poling direction. Further, this concept was developed theoretically to investigate the effect of poling angle on sensing and actuation capabilities of the piezoelectric materials particularly operating in d33 mode. To demonstrate the effect, a cantilever based interdigitated electrode configuration has been considered with different materials including 0.3BaTiO3-0.7NaNbO3 (BT-NNb), K0.475Na0.475Li0.05(Nb0.92Ta0.05Sb0.03) (KNLNTS), Pb(Mg1/3Nb2/3)O3–PbTiO3 (PMN-PT) and Pb[ZrxTi1-x] (PZT-5A) . In addition to poling direction, the effect of electrode width and electrode separation distance was also investigated. Upon poling tuning, enhanced was displayed only by BT-NNb and PMN-PT due to large difference between magnitudes of piezoelectric strain coefficients. On the other hand, in terms of sensing and actuation substantial increment was observed these two materials while the performance of PZT-5A deteriorated with increasing poling angle. An increment of 4400% and 87% was observed in BT-NNb and PMN-PT respectively in actuation while sensing performance increased by ∼2460% and ∼210% for BT-NNb and PMN-PT respectively.

Large-area electrode design for vertical electrical impedance scanning of concrete bridge decks.

Vertical electrical impedance (VEI) testing is a method that was developed specifically for quantifying the level of protection against chloride ingress in concrete bridge decks. A significant operational difficulty associated with VEI testing has been establishing the required rebar tap as a ground reference. As described in this work, the use of a large-area electrode (LAE) can potentially remove the need for a rebar tap and therefore significantly simplify and accelerate the VEI testing process. The specific objective of the research was to develop both theoretical and practical guidance for the design of an LAE for VEI testing. To investigate several variables that can affect the accuracy of VEI measurements obtained using an LAE connection, including various combinations of deck cover and water resistivity values, electrode separation distance, counter electrode (CE) effective area, and area ratio between the LAE and the CE, an analytical model (AM) and a finite-element model (FEM) were developed and validated with laboratory and field experiments. From the results of the AM and FEM simulations and the results of the laboratory and field experiments, LAE design considerations were developed for each of these variables that should allow proper implementation of a VEI measurement system using an LAE connection.

A review and comparative assessment of direct ammonia fuel cells

In this study, we present a comparative assessment of direct ammonia fuel cells and a discussion of these from various perspectives by considering the effective criteria. The effect of electrolyte and electrode materials, electrolyte thicknesses and operating temperatures on the performance of direct ammonia fuel cells are studied and discussed comparatively for evaluation purposes. A comparison of which cell types and configurations provide the optimum performance is conducted by utilizing the experimental results reported in the literature. The results of this study are expedient to provide important inferences about the performances of direct ammonia fuel cells. Ammonia fed oxygen ion conducting Samarium doped ceria electrolyte based solid oxide fuel cells have comparatively the highest peak power density of 1190 mW/cm2 when operated at 650 °C with a 10 µm thick electrolyte. Direct ammonia proton conducting electrolyte based solid oxide fuel cells have lower cell performance than oxygen ion conducting fuel cells due to the dilution of hydrogen at the anode by undecomposed ammonia as well as formed nitrogen gas. The operating temperature of the fuel cell and electrolyte thickness affect the cell performance considerably. A 200 °C increase in operating temperature increases the peak power density by nearly three to four times for ammonia fed solid oxide fuel cells. The molten alkaline electrolyte based fuel cells can be a promising technology. Further research is required for these type of fuel cells to investigate their performance with low electrode separation distance and more conductive alkaline electrolytes.

Investigation of the in-plane and out-of-plane electrical properties of metallic nanoparticles in dielectric matrix thin films elaborated by atomic layer deposition

Pt nanoparticles in a Al2O3 dielectric matrix thin films are elaborated by means of atomic layer deposition. These nanostructured thin films are integrated in vertical and planar test structures in order to assess both their in-plane and out-of-plane electrical properties. A shadow edge evaporation process is used to develop planar devices with electrode separation distances in the range of 30 nm. Both vertical and planar test structures show a Poole–Frenkel conduction mechanism. Low trap energy levels (<0.1 eV) are identified for the two test structures which indicates that the Pt islands themselves are not acting as traps in the PF mechanism. Furthermore, a more than three order of magnitude current density difference is observed between the two geometries. This electrical anisotropy is attributed to a large electron mobility difference in the in-plane and out-of-plane directions which can be related to different trap distributions in both directions.

Improving the mass transport of copper-complex redox mediators in dye-sensitized solar cells by reducing the inter-electrode distance.

In this work, we study the influence of the distance between electrodes on the performance of dye-sensitized solar cells based on TiO2 using the organic dye LEG4 and a Cu(dmp)2 redox couple (dmp = dimethyl phenantroline). The solar cells are characterized by a large open circuit voltage of up to 1.03 V, and an efficiency of 8.2% has been achieved for a 5.3 μm thick TiO2 film using an epoxy resin-based sealed cell configuration with a minimal separation between electrodes. Transient short-circuit photocurrent measurements up to an intensity of 3 Suns show a significant decay in photocurrent after an initial peak current upon switching on the light for larger distance, resulting in a lower steady state photocurrent. For the smaller distance cells, the steady state photocurrent is linear with light intensity up to 2 Suns. Charge extraction measurements under short-circuit conditions show that reducing the distance between electrodes increases the electron collection efficiency and thus, the attainable photocurrent. Recombination losses increase with larger electrode separation distance and higher light intensity due to mass transport limitation of the redox mediator. Electrochemical impedance measurements confirm the effect of electrode distance on the redox couple transport, showing an additional loop with increasing distance. For the configuration where the TiO2 film is in very close proximity to the PEDOT-covered counter electrode, inductive behavior is observed at low frequencies. The inductive behavior disappears with the incorporation of an insulating porous ZrO2 layer. The equivalent circuit for the solar cell has been expanded to include this effect.

Effects of Electrically Activated Silver–Titanium Implant System Design Parameters on Time-Kill Curves Against Staphylococcus aureus

Implant-associated infections pose serious threats to patients in terms of morbidity, mortality, and medical costs. This paper focuses on the quantitative assessment of the antimicrobial efficacy of a silver-based prophylactic system for orthopaedic implant applications. The implant system is configured to induce controlled local administration of silver ions via low intensity direct current activation (1–14 µA). We developed a broth-based in vitro testing model to evaluate the effects of important design parameters on the antimicrobial efficacy of the system over a 48-h interval. The time-kill curves obtained with various parameter levels were analyzed through a longitudinal model. Five parameters were investigated independently through one-way factorial experiments (n = 12) against Staphylococcus aureus. In phase 1 of the study, we investigated the effect of cathode material on system performance. We also determined the linear structure of the longitudinal model based on the Akaike information criterion by fitting the empirical data to multiple candidate model structures. The results show that substituting the silver cathode with titanium does not weaken the antimicrobial efficacy of the system (p = 0.9946). In phase 2, a detailed analysis with four design parameters was conducted using the silver–titanium configuration. The performance of the system was found to be independent of the electrode separation distance (p = 0.9926) and the pulsating current frequency (p = 0.9956). However, the anode surface area (p < 0.0001) and the current intensity (p < 0.0001) influenced the antimicrobial efficacy in an interactive manner. Overall, this study characterizes the in vitro antimicrobial efficacy of the proposed system and provides a reference of design parameters for future product engineering.

Influence of Molecular Orientation on Charge-Transfer Processes at Phthalocyanine/Metal Oxide Interfaces and Relationship to Organic Photovoltaic Performance

The effect of the molecular orientation distribution of the first monolayer of donor molecules at the hole-harvesting contact in an organic photovoltaic (OPV) on device efficiency was investigated. Two zinc phthalocyanine (ZnPc) phosphonic acids (PA) deposited on indium tin oxide (ITO) electrodes are compared: ZnPc(PA)4 contains PA linkers in all four quadrants, and ZnPcPA contains a PA linker in one quadrant. ZnPcPA monolayers exhibited a broad distribution of molecular orientations whereas ZnPc(PA)4 adsorption produced a monolayer with a narrower orientation distribution with the molecular plane more parallel to the ITO surface. We used potential-modulated attenuated total reflectance spectroelectrochemistry (PM-ATR) to characterize the charge-transfer kinetics of these films and show that the highest rate constants correspond to ZnPc subpopulations that are oriented more parallel to the ITO surface plane. For ZnPc(PA)4, rate constants exceeded 104 s–1 and are among the highest ever reported for a surface-confined redox couple, which is attributable to both its orientation and the small ZnPc–electrode separation distance. The performance of OPVs with ITO hole-harvesting contacts modified with ZnPc(PA)4 was comparable to that achieved with highly activated bare ITO contacts, whereas for ZnPcPA-modified contacts, the OPV performance was similar to that observed with (hole-blocking) alkyl-PA modifiers. These results demonstrate the synergism between molecular structure, energetics, and dynamics at interfaces in OPVs.