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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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At least 325 records · Page 18
All sourcesNASA NTRSDOE OSTI
DOE OSTI2015

Multifunctional oxides for integrated manufacturing of efficient graphene electrodes for organic electronics

Using multi-functional oxide films, we report on the development of an integration strategy for scalable manufacturing of graphene-based transparent conducting electrodes (TCEs) for organic electronics. A number of fundamental and process challenges exists for efficient graphene-based TCEs, in particular, environmentally and thermally stable doping, interfacial band engineering for efficient charge injection/extraction, effective wetting, and process compatibility including masking and patterning. Here, we show that all of these challenges can be effectively addressed at once by coating graphene with a thin (>10 nm) metal oxide (MoO{sub 3} or WO{sub 3}) layer. We demonstrate graphene electrode patterning without the need for conventional lithography and thereby achieve organic light emitting diodes with efficiencies exceeding those of standard indium tin oxide reference devices.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
NASA NTRS1972

Two-axis leveling detector system

Electro-mechanical device for measuring tilt angles in order to establish level base without optical reference is described. Angular displacement is detected by movement of bubble in conducting fluid containing electrode network. Electrical signal causes compensation for small movements in horizontal and vertical planes.

Weiner, L.↗
DOE OSTI2016

Technique for the comparison of light spectra from natural and laboratory generated lightning current arcs

A technique was developed for the comparison of observed emission spectra from lightning current arcs generated through self-breakdown in air and the use of two types of initiation wire, aluminum bronze and nichrome, against previously published spectra of natural lightning events. A spectrograph system was used in which the wavelength of light emitted by the lightning arc was analyzed to derive elemental interactions. A lightning impulse of up to 100 kA was applied to a two hemispherical tungsten electrode configuration which allowed the effect of the lightning current and lightning arc length to be investigated. A natural lightning reference spectrum was reconstructed from literature, and generated lightning spectra were obtained from self-breakdown across a 14.0 mm air gap and triggered along initiation wires of length up to 72.4 mm. A comparison of the spectra showed that the generated lightning arc induced via self-breakdown produced a very similar spectrum to that of natural lightning, with the addition of only a few lines from the tungsten electrodes. A comparison of the results from the aluminum bronze initiation wire showed several more lines, whereas results from the nichrome initiation wire differed greatly across large parts of the spectrum. This work highlights the potential use for spectrographic techniques in the study of lightning interactions with surrounding media and materials, and in natural phenomena such as recently observed ball lightning.

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗
DOE OSTI2018

Iridium-Based Nanowires as Highly Active, Oxygen Evolution Reaction Electrocatalysts

Iridium-nickel (Ir-Ni) and iridium-cobalt (Ir-Co) nanowires have been synthesized by galvanic displacement and studied for their potential to increase the performance and durability of electrolysis systems. Performances of Ir-Ni and Ir-Co nanowires for the oxygen evolution reaction (OER) have been measured in rotating disk electrode half-cells and single-cell electrolyzers and compared with commercial baselines and literature references. The nanowire catalysts showed improved mass activity, by more than an order of magnitude compared with commercial Ir nanoparticles in half-cell tests. The nanowire catalysts also showed greatly improved durability, when acid-leached to remove excess Ni and Co. Both Ni and Co templates were found to have similarly positive impacts, although specific differences between the two systems are revealed. In single-cell electrolysis testing, nanowires exceeded the performance of Ir nanoparticles by 4-5 times, suggesting that significant reductions in catalyst loading are possible without compromising performance.

77 NANOSCIENCE AND NANOTECHNOLOGY↗
NASA NTRS2004

The Role of Plasma in Plasma Enhanced Chemical Vapour Deposition of Nanostructure Growth

Chemical vapour deposition (CVD) has become the preferred process for high yield growth of carbon nanotubes and nanofibres because of its ability to pattern growth through lithographic positioning of transition metal catalysts on substrates. Many potential applications of nanotubes such as field emitters [1] require not only patterned growth but also vertical alignment. Some degree of ali,ment in thermal CVD processes can be obtained when carbon nanotubes are grown closely together as a result of van der Waals interactions. The ali,onment however is marginal, and the van der Waals prerequisite makes growth of freestanding nanofibres with thermal CVD unrealizable. The application of electric fields as a means of ali,onment has been shown to overcome this limitation [2-5], and highly aligned nanostructures can be grown if electric fields on the order of 0.5 V/microns are employed. Plasma enhanced CVD in various configurations including dc, rf, microwave, inductive and electron cyclotron resonance has been pursued as a means of enabling alignment in the CVD process. However, the sheath fields for the non-dc sources are in general not sufficient for a high degree of ali,pment and an additional dc bias is usually applied to the growth substrate. This begs the question as to the actual role of the plasma. It is clear that the plasma itself is not required for aligned growth as references [3] and [4] employed fields through small applied voltages (3-20 V) across very small electrode spacings (10-100 microns) and thus avoided striking a discharge.

Hash, David B.↗
NASA NTRS2013

Dielectrophoresis-Based Particle Sensor Using Nanoelectrode Arrays

A method has been developed for concentrating, or partly separating, particles of a selected species from a liquid or gas containing these particles, and flowing in a channel. An example of this is to promote an accumulation (and thus concentration) of the selected particle (e.g., biological species such as E. coli, salmonella, anthrax, tobacco mosaic virus or herpes simplex, and non-biological materials such as nano- and microparticles, quantum dots, nanowires, nano - tubes, and other inorganic particles) adjacent to the first surface. Additionally, this method can also determine if the particle species is present in the liquid. This is accomplished by providing an insulating material in an interstitial volume between two or more adjacent nanostructure electrodes. It can also be accomplished by providing a functionalizing substance, located on a selected region of the insulating material surface, which promotes attachment of the selected species particles to the functionalized surface, and measuring a selected electrical property such as electrical impedance, conductance, or capacitance. A time-varying electrical field E, having a root-mean-square intensity of E(sup 2) rms, with a non-zero gradient in a direction transverse to the liquid or fluid flow direction, is produced by a nanostructure electrode array with a very high-magnitude gradient near exposed electrode tips. A dielectrophoretic force causes the selected particles to accumulate near the electrode tips, if the medium and selected particles have substantially different dielectric constants. An insulating material surrounds most of the nanostructure electrodes, and a region of the insulating material surface is functionalized to promote attachment of the selected particle species to the surface. An electrical property value Z(meas) is measured at the functionalized surface, and is compared with a reference value Z(ref) to determine if the selected species particles are attached to the functionalized surface. Some advantages of this innovation are that an array of nanostructure electrodes can provide an electric field intensity gradient that is one or more orders of magnitude greater than the corresponding gradient provided by a conventional microelectrode arrangement, and that, as a result of the high-magnitude field intensity gradients, a nanostructure concentrator can trap particles from high-speed microfluidic flows. This is critical for applications where the entire analysis must be performed in a few minutes

Li, Jun↗
DOE OSTI2015

A Dual Stage Sodium Thermo-Electro-Chemical Converter

The need for reliable and distributable energy sources is evident given the current forecasting of the world’s energy demand [1]. One prominent obstacle is the lack of an efficient direct heat-to-electricity conversion technology. The sodium thermo-electro-chemical converter (Na-TECC) is a highly efficient thermally regenerative electrochemical system (TRES) that can fill this void. The advantage of the Na-TECC over other direct conversion technologies is that it is a closed device (unlike fuel cells) requiring nothing more than a heat input (similar to thermoelectrics). It also has a high power density (> 1 W/cm2) and specific power up to 0.5 kW/kg , with the potential to achieve > 45% heat to electricity conversion efficiencies [2]. Furthermore, the converter rejects heat at a temperature hot enough to make it amenable for cogeneration, potentially under air-cooled operation. This electrochemical technology uses a special ion-selective solid-electrolyte called beta-alumina (Na2O•11Al2O3), that is highly conductive to sodium cations. A more conducting variation of this compound is beta”-alumina (Na2O•MgO•5Al2O3), where the magnesium acts as a stabilizer [3]. In the device, liquid sodium enters an evaporator where it is heated isobarically and vaporizes. The vapor is then oxidized at the interface between the anode and the solid-electrolyte. The Na-TECC generates electric power by allowing the high pressure oxidized sodium vapor ions to expand isothermally through the solid-electrolyte from the anode to the cathode. The liberated electrons are simultaneously conducted through an external load and recombine with the cations at the cathode. The low pressure sodium vapor is subsequently condensed and a wick pumps the liquid into the high pressure plenum to complete the cycle. Previous Na-TECCs have achieved efficiencies of 18% due to practical losses, whereas the potential efficiencies are above 45% [4]. Thermodynamic limitations and design constraints have limited previous devices from attaining these record efficiencies. Specifically, the maximum potential voltage in these previous devices was substantially reduced by the kinetic limitations of the charge transfer in the cathode (referred to as the overpotential) and by Joule heating losses due to the solid-electrolyte resistance, electrode resistance, and current collector resistance. Moreover, previous devices experienced a steady loss in performance throughout their lifetime. The drop in performance has been attributed to the electrolyte undergoing thermal and chemical breakdown due to crack propagation, loss of sodium oxide, and the formation of molten dendrites that create electrical shorts [5]. Finally, previous designs have also had a substantial problem with proper thermal management, with some showing thermal losses as great as 50% of the heat input. To improve the efficiency, a dual stage conversion process is being explored. Rather than using one isothermal expansion step, the dual cycle will employ two separate electrolytes to allow two separate expansion steps: one at the high temperature, and another at an intermediate temperature. This new cycle is thermodynamically favorable as it allows for regeneration from the isobaric cooling of the first expansion step, and reheat to complete the expansion in the second step. This allows the engine to reach a lower condenser temperature than its single stage counterpart, thus increasing the overall efficiency. The temperature drop across each electrolyte in the dual stage device (e.g., ~ 400 K) is smaller than the temperature drop across a comparable single stage device (e.g., ~ 800 K). This is amenable for better thermal management and allows for less heat loss. This will also mitigate the thermal shock across the very thin (< 1 mm) solid electrolytes, reduce crack propagation and limit the percolation of the molten dendrites, and ultimately increase the lifetime of the device. As an additional benefit the dual stage can be designed using planer geometries, rather than tubular geometries used in previous single stage models, which can be manufactured less expensively. This modified geometry can be tailored to improve the thermal management by reducing the radiation losses, which has been the biggest source of thermal losses [2]. A dual stage concept for the Na-TECC has never been demonstrated in literature. In this presentation, the operation of a single stage device will be revisited and, by adopting concepts used for similar converters, the thermodynamic operation of the dual stage will be developed [6]. Using the dual stage approach, the efficiency and power equations have been redefined to include regeneration and reheat. Questions such as what current densities optimize the power output or which intermediate temperature maximizes the efficiency will also be answered. Initial calculations of the dual stage show that the thermal management is the most sensitive parameter. Although the ideal voltage produced by the dual stage can be higher, there are potential drawbacks. For example, by using a lower condenser temperature the dual stage device will have a higher open circuit voltage, but it will also have a larger overpotential due to the limited cathodic kinetics that occur at a lower temperature. In short, there are several trade-offs in this device that need to be balanced. It will be demonstrated that the dual stage device must have lower thermal losses than a single stage device if it is to have a higher efficiency.

14 SOLAR ENERGY↗
DOE OSTI2016

Thermodynamics of a Dual Stage Sodium Thermo-Electro-Chemical Converter

The need for reliable and distributable energy is evident, but one prominent obstacle is the lack of an efficient direct heat-to-electricity converter. The sodium thermo-electro-chemical converter (Na-TECC) is a highly efficient thermally regenerative electrochemical system (TRES) that can fill this void. This electrochemical technology uses an ion-selective solid-electrolyte called beta-alumina that is highly conductive to sodium cations. The Na-TECC generates electric power by allowing high pressure sodium cations to expand isothermally through the solid-electrolyte. Theoretically, a device interacting with thermal reservoirs at 1150 K and 550 K should operate above 45% efficiency, but actual devices have not surpassed efficiencies of 20%. The maximum potential voltage in these previous devices was substantially reduced by the kinetic limitations of the charge transfer in the cathode (referred to as the overpotential) and by Joule heating losses due to the solid-electrolyte resistance, electrode resistance, and current collector resistance. To overcome this discrepancy, a dual stage conversion process is being proposed. Rather than using one isothermal expansion step, the dual cycle will employ two separate electrolytes to allow two separate expansion steps: one at the high temperature, and another at an intermediate temperature. This new cycle is thermodynamically favorable as it allows for regeneration from the isobaric cooling of the first expansion step, and reheat to complete the expansion in the second step. This allows the engine to reach a lower condenser temperature than its single stage counterpart for a given heat input, resulting in an increased overall efficiency. The temperature drop across each electrolyte in the dual stage device (e.g., ~ 400 K) is smaller than the temperature drop across a comparable single stage device (e.g., ~ 800 K). This makes the device amenable to better thermal management and allows for less heat loss. Also, the intermediate stage will mitigate the thermal shock across the very thin (< 1 mm) solid electrolyte, reduce crack propagation, limit the percolation of the molten dendrites, and ultimately increase the lifetime of the device. A dual stage concept for the Na-TECC has never been demonstrated in literature, so it is necessary to properly re-define the thermodynamic parameters such as heat loss, maximum power, and optimal current density. Certain drawbacks from a dual stage concept will also be addressed, such as the need for larger electrochemical area and the increased pressure losses. It will be demonstrated that the dual stage device must have lower thermal losses than a single stage device if it is to have a higher efficiency. The improved operation of the Na-TECC can have a transformational effect on small combined heat and power (CHP) systems at the 1-5 kW range.

14 SOLAR ENERGY↗
DOE OSTI2025

Electrical Resistivity Tomography data from 2016 to 2018 at the Lower Montane site in the East River Watershed, Colorado

This dataset contains time-lapse Electrical Resistivity Tomography (ERT) data along a transect located on the northeast-facing hillslope at the lower montane site (Pumphouse site) in the upper East River Watershed. The monitoring dataset covers the period from November 2, 2016, to August 6, 2018. In addition, the archive also contains a baseline dataset from October 9, 2016. The ERT transect consisted of 128 electrodes with an electrode spacing of 1.25 m. The acquisition system was located in the middle of the transect, about 50 m on one side, and included an MPT (Multi-Phase Technologies) ERT system, a mini computer, and batteries with solar panels. Acquisition occurred daily under normal circumstances. The first 16 electrodes (from the upper end of the transect) could not be used after the cable was damaged during the 2017–2018 winter. Also, due to multiple failures in the power system, the temporal resolution of the data is much lower in 2018 compared to 2016 and 2017. The data have been processed and used in Dafflon et al., 2023, and the baseline dataset was used in Falco et al., 2019 (see reference list). This archive contains the measurements (ER.zip containing csv files) for each of the 326 acquisition times and a filtered version where only electrodes 17 to 128 are included (ERT_sm.zip containing csv files). The archive also contains the baseline dataset and two acquisitions with full reciprocals (ERT_RB.zip containing csv files), as well as all the raw MPT files (ERT_raw_MTP.zip). The geometry (electrode position and elevation) is provided in Universal Transverse Mercator (UTM) 13N Geoid2012AB in the file named ERT_Location.csv. The archive contains 1 *.csv data files, four *.zip files, and three metadata *.csv files. This work was supported by the Watershed Function Science Focus Area at Lawrence Berkeley National Laboratory funded by the US Department of Energy, Office of Science, Biological and Environmental Research under Contract No. DE-AC02-05CH11231.

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2024

Sub-volt conversion of activated biochar and water for H 2 production near equilibrium via biochar-assisted water electrolysis

Sluggish water oxidation reactions limit water electrolysis for H 2 production, which can be alleviated by the use of carbon-based ma- terials like agricultural wastes as reducing agents. Biochar from such biomass can reduce equilibrium cell potentials at standard condi- tions from 1.23 V to 0.21 V by avoiding direct water splitting at the anode. However, some challenges hinder biochar oxidation, including poor biochar binding, electrode caking, and surface passivation. We find that enhanced C/O ratio, crystallinity, and negative zeta potential improve biochar oxidation kinetics at mod- erate temperatures. Smaller particle sizes and better mixing pre- vent electrode caking, enhancing biochar stability. Here, we report sub-volt biochar-coupled H 2 production, often referred to as a bio- char-assisted water electrolysis (BAWE), yielding 250 mA/g cat H 2 current at 100% Faradaic efficiency. Over 1 mA current was observed at a near-equilibrium cell potential of 0.2 V cell potential. Using a single-junction solar cell-powered BAWE, 15 mA H 2 is generated at 1 Sun, resulting in 4.8% solar-to-hydrogen efficiency, equivalent to 35% when the energy of H 2 relative to H 2 O (without biochar) is assumed.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2018

Secondary-Phase Stochastics in Lithium-Ion Battery Electrodes

Lithium-ion battery electrodes exhibit complex interplay among multiple electrochemically coupled transport processes, which rely on the underlying functionality and relative arrangement of different constituent phases. The electrochemically inactive solid phases (e.g., conductive additive and binder, referred to as the secondary phase), while beneficial for improved electronic conductivity and mechanical integrity, may partially block the electrochemically active sites and introduce additional transport resistances in the pore (electrolyte) phase. In this work, the role of mesoscale interactions and inherent stochasticity in porous electrodes is elucidated in the context of short-range (interface) and long-range (transport) characteristics. The electrode microstructure significantly affects kinetically and transport-limiting scenarios and thereby the cell performance. The secondary-phase morphology is also found to strongly influence the microstructure-transport-kinetics interactions. Apropos, strategies have been proposed for performance improvement via electrode microstructural modifications.

25 ENERGY STORAGE↗
DOE OSTI2016

Tuning back contact property via artificial interface dipoles in Si/organic hybrid solar cells

Back contact property plays a key role in the charge collection efficiency of c-Si/poly(3,4-ethylthiophene):poly(styrenesulfonate) hybrid solar cells (Si-HSCs), as an alternative for the high-efficiency and low-cost photovoltaic devices. In this letter, we utilize the water soluble poly (ethylene oxide) (PEO) to modify the Al/Si interface to be an Ohmic contact via interface dipole tuning, decreasing the work function of the Al film. This Ohmic contact improves the electron collection efficiency of the rear electrode, increasing the short circuit current density (J{sub sc}). Furthermore, the interface dipoles make the band bending downward to increase the total barrier height of built-in electric field of the solar cell, enhancing the open circuit voltage (V{sub oc}). The PEO solar cell exhibits an excellent performance, 12.29% power conversion efficiency, a 25.28% increase from the reference solar cell without a PEO interlayer. The simple and water soluble method as a promising alternative is used to develop the interfacial contact quality of the rear electrode for the high photovoltaic performance of Si-HSCs.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
DOE OSTI2015

Decoupling optical and electronic optimization of organic solar cells using high-performance temperature-stable TiO{sub 2}/Ag/TiO{sub 2} electrodes

An electrode structured with a TiO{sub 2}/Ag/TiO{sub 2} (TAT) multilayer as indium tin oxide (ITO) replacement with a superior thermal stability has been successfully fabricated. This electrode allows to directly tune the optical cavity mode towards maximized photocurrent generation by varying the thickness of the layers in the sandwich structure. This enables tailored optimization of the transparent electrode for different organic thin film photovoltaics without alteration of their electro-optical properties. Organic photovoltaic featuring our TAT multilayer shows an improvement of ∼12% over the ITO reference and allows power conversion efficiencies (PCEs) up to 8.7% in PTB7:PC{sub 71}BM devices.

36 MATERIALS SCIENCE↗
DOE OSTI2023

Protocol for assembling and operating bipolar membrane water electrolyzers

Renewable energy-driven bipolar membrane water electrolyzers (BPMWEs) are a promising technology for sustainable production of hydrogen from seawater and other impure water sources. Here, we present a protocol for assembling BPMWEs and operating them in a range of water feedstocks, including ultra-pure deionized water and seawater. We describe steps for membrane electrode assembly preparation, electrolyzer assembly, and electrochemical evaluation. For complete details on the use and execution of this protocol, please refer to Marin et al. (2023).

Rios Amador, Isabela↗
DOE OSTI2020

Influence of Proton Activity Gaps between Electrodes on Open-Circuit Potential of H 2 /H 2 and H 2 /Air Cells

Polymer -electrolyte-fuel-cell open-circuit voltages (OCVs) are exactly defined by equation (1), where cathode and anode proton activities [(aH+)cathode and (aH+)anode, respectively] usually are identical, so the third term in the right-hand side of equation (2) is ignored. OCV=E0+RT/2F*ln(a1/2 O2*(a2 H+)cathode/aH2O)-RT/2F*ln((a2 H+)anode/aH2) (1) =E0+RT/2F*ln(a1/2 O2*aH2/aH2O)+RT/2F*ln((a2 H+)cathode/(a2 H+)anode) (2) Water vapor pressure is a colligative property that fundamentally correlates to electrolyte concentrations in aqueous solutions. Proton activity is a function of acid concentration, such as pH, when electrolytes are acids. In polymer-electrolyte membranes, water vapor pressure and acid concentration are understood as relative humidity (RH) and water uptake (λ), respectively, where λ represents number of water molecules per sulfonic acid molecule. Several investigations have reported the relationship between RH and λ, meaning that proton activities and associated water uptakes are intimately related to RH. In actual fuel cell operation, cathode RH is determined by ambient-atmosphere and/or humidifier RH(s), and anode RH depends on hydrogen-circulator RH. Therefore, RH is not always identical at both electrodes, and the difference between electrode RHs is considerable during dry operation of polymer electrolyte fuel cells. Therefore, the third term in the right-hand side of equation (2) may be significant for dry operation. We measured OCVs when hydrogen was supplied to both electrodes at 80°C. One electrode (A) was fixed at 30% RH, while RH at the other electrode (B) was varied (0, 5, 10, 20, and 30%). Measured OCVs varied from 0 to 75 mV. For fuel cell tests, electrode A was supplied with hydrogen at 30% RH; electrode B, oxygen at 0, 5, 10, 20, and 30% RH. OCVs deviated from that measured when RH at electrode B was 30%, increasing from 0 to 60 mV with decreasing RH at electrode B. Results are also shown in Figure 1. Proton activities of both electrodes were thermodynamically calculated. The Gibbs–Duhem relation was applied to obtain molar Gibbs free energies of water and sulfonic acid, and proton activity coefficient was calculated using the Gibbs free energy of sulfonic acid and the relationship between RH and λ1–4, assuming that protons and sulfonic anions show identical ionic-activity coefficients. OCVs were estimated using the third term in the right-hand side of equation (2). Results are shown in Figure 1. Fuel-cell current–voltage performance was poor when RHs at the anode and cathode were 30 and 20%, respectively. To determine kinetic current, we measured the oxygen-reduction reaction (ORR) using a rotating-disk electrode (RDE) in concentrated-acid aqueous solutions, which modeled catalyst-layer ionomers. Kinetic currents decreased with acid concentrations. References T. A. Zawodzinski, Jr., C. Derouin, S. Radzinski, R. J. Sherman, V. T. Smith, T. E. Springer and S. Gottesfeld , J. Electrochem. Soc., 140,1041 (1993) P. K. Das and A. Z. Weber, Proceedings of the ASME 2013 11th Fuel Cell Science, Engineering and Technology Conference, Fuel Cell 18010 (2013) V. A. Sethuraman, J. W. Weidner, A. T. Haug, S. Motupally,b and L. V. Protsailo, J. Electrochem. Soc., 155, B50 (2008) A. Kusoglu and A. Z. Weber, Chem. Rev., 117, 987 (2017) Figure 1

Yoshida, Toshihiko↗
NASA NTRS1973

Low phase noise digital frequency divider

A low phase noise frequency divider composed of a grating arrangement is disclosed. The grating arrangement supplies selected portions of an input reference signal to be divided to a tuned circuit without any phase noise due to the grating action. The arrangement which in one embodiment consists of an FET is connected to the tuned circuit input to short out the input except when the input reference signal amplitude crosses ground level in a positive direction and a gate enabling signal is present at the gate electrode of the FET. The gate enabling signal alone does not decouple the tuned circuit input from ground, therefore phase noise, due to the leading and trailing edges of each gate-enabling signal, is substantially eliminated.

Lutes, G. F., Jr.↗
NASA NTRS1977

The effects of cations and anions on hydrogen chemisorption at Pt

Experimental evidence based on linear sweep voltammetry is presented to substantiate the view that ionic adsorption substantially shifts electrode potentials in addition to the relative heights of the hydrogen adsorption peaks. HClO4 and HF are chosen as better reference electrolytes for anion studies. The voltammetry curves for 0.1M HF and 0.1M HClO4 as well as the effect of adding successively increasing amounts of H2SO4 to these electrolytes are discussed. The measurements are also extended to alkaline solutions. Mechanisms whereby the addition of various cations and anions to electrolytes such as HF and HClO4 can induce changes in the structure of the hydrogen adsorption region in the voltammetry curves are identified: (1) blocking of sites by anion adsorption and coupling of hydrogen adsorption and anion desorption, (2) modification in the hydrogen adsorption energies for sites adjacent to adsorbed anions, (3) changes in the potential distribution across the interface, and (4) surface restructuring.

Huang, J. C.↗