Abstract: The invention relates to a process for electrochemically converting anhydrous hydrogen halide, such as hydrogen chloride, hydrogen fluoride, hydrogen bromide and hydrogen iodide, to essentially dry halogen gas, such as chlorine, fluorine, bromine and iodine gas, respectively. In a preferred embodiment, the present invention relates to a process for electrochemically converting anhydrous hydrogen chloride to essentially dry chlorine gas. This process allows the production of high-purity chlorine gas. In this process, molecules of essentially anhydrous hydrogen chloride are transported through an inlet of an electrochemical cell. The molecules of the essentially anhydrous hydrogen chloride are oxidized at the anode of the cell to produce essentially dry chlorine gas and protons, which are transported through the membrane of the cell. The transported protons are reduced at the cathode to form either hydrogen gas, water or hydrogen peroxide.

Abstract: A sintered laminated structure including a plurality of ceramic layers made of ceramic materials different from one another, wherein each of the ceramic layers is provided with through-holes passing each of the ceramic layers.

Abstract: The present invention relates to an electrochemical cell and a process for converting anhydrous hydrogen halide to halogen gas using a membrane-electrode assembly (MEA) or a separate membrane and electrode arrangement, such as gas diffusion electrodes with a membrane.

Abstract: A cathode assembly comprising a cathode, an ion-exchange membrane, and an electroconductive porous member permeable to gas and liquid sandwiched between the cathode and the membrane. The porous member may have, deposited on a part thereof, a catalyst active in hydrogen generation. The porous member preferably is in the form of a plate, sheet, fibers, web, paper, net, or sinter of any of these, and comprises at least a carbonaceous material and has a thickness of from 0.05 to 5 mm and a porosity of from 10 to 95%. Also disclosed is a method of reactivating a cathode assembly, which comprises conducting electrolysis using the cathode assembly until its activity decreases, and then depositing a catalyst active in hydrogen generation on the porous member.

Abstract: The invention relates to a novel rhodium sulfide catalyst for the reduction of oxygen in industrial electrolyzers. The catalyst is highly resistant towards corrosion and poisoning by organic species, thus resulting particularly suitable for use in aqueous hydrochloric acid electrolysis, when technical grade acid containing organic contaminants is employed.

Abstract: The invention provides an improved proton exchange membrane for use in electrochemical cells having internal passages parallel to the membrane surface comprising permanent tubes preferably placed at the ends of the fluid passages. The invention also provides an apparatus and process for making the membrane, membrane and electrode assemblies fabricated using the membrane, and the application of the membrane and electrode assemblies to a variety of devices, both electrochemical and otherwise. The passages in the membrane extend from one edge of the membrane to another and allow fluid flow through the membrane and give access directly to the membrane.

Abstract: An anode includes an anode cup, a membrane and ion source material, the anode cup and membrane forming an enclosure in which the ion source material is located. The anode cup includes a base section having a central aperture and the membrane also has a central aperture. A jet is passed through the central apertures of the base section of the anode cup and through the membrane allowing plating solution to be directed at the center of a wafer being electroplated.

Abstract: A mist preventing cover for an electrode has an upper end which surrounds and is sealed to an electrode above the surface of the electrolyte in an electrowinning cell to thereby form a substantially closed chamber above the electrolyte surface. The lower end of the cover extends below the electrolyte surface and prevents escape of bubbles generated at the surfaces of the electrode, while permitting the passage of electrolyte to the electrode. The bubbles rise to the surface of the electrolyte, where they burst and generate a mist in the closed chamber formed by the electrode cover. The mist contains droplets having substantially the same composition as the electrolyte, as well as gaseous components including water vapor, gas generated by the electrode, and entrapped ambient air.

Abstract: A zero-gap type electrolytic cell 11 characterized as having a hydrophilic liquid-permeable material 16 interposed between an ion-exchange membrane 12 and a gas diffusion cathode 17. The reaction product passes through the liquid-permeable material and disperses toward edges of the liquid-permeable material before being withdrawn. Hence, the withdrawal direction for the target reaction product is not opposite the feed direction for the reactant gas.

Abstract: The invention pertains to linear electrochemical functional elements which have strip-shaped ion-exchange membranes (IEMs) and/or hydrogen-diffusion electrodes accessible at the ends which are enclosed on all sides in an insulating manner by a jacket of a solid material. The invention describes the structure, production, and use of the functional elements in electrochemical measuring techniques. In one embodiment, a charge state indicator is created by the incorporation of a lead/lead sulfate half-cell into a lead/lead oxide cell. This coupling takes place via a linear functional element in the form of an installed ion-exchanger membrane. It makes it possible to measure three voltage values on the cell and to evaluate them in order to determine the current charge state by conventional methods.

Abstract: Gas Diffusion Electrodes (GDES) play a pivotal role in clean energy production as well as in electrochemical processes and sensors. These gas-consuming electrodes are typically designed for liquid electrolyte systems such as phosphoric acid and alkaline fuel cells, and are commercially manufactured by hand or in a batch process. However, GDEs using the new electrolytes such as conductive polymer membranes demand improved electrode structures.This invention pertains to GDEs and gas diffusion media with new structures for systems using membrane electrode assemblies (MEAs), and automated methods of manufacture that lend themselves to continuous mass production Unexpected improvements in gas and vapor transport through the electrode are realized by incorporating a new dispersion process in the construction, reformulating the applied mix with solution additives, and creating a novel coating structure on a conductive web.

Abstract: This invention covers a cathodic element free from asbestos fibres that can be obtained by deposition after filtration through a porous medium of an aqueous suspension comprising electrically conductive fibres, at least one cationic polymer, at least one electocatalytic agent, at least one pore-forming agent and at least one binder selected from among the fluoropolymers. The invention also covers a method for preparing such a cathodic element.

Abstract: The invention concerns a diaphragm chlor-alkali electrolysis cell comprising a cover, a conductive base for supporting the anodes and a cathode in the form of a box provided with internal wall, external wall and tubular fingers made of a mesh or perforated sheet covered with a porous diaphragm. One or more copper sheets for electric current distribution are fixed to the cathode external walls. The connection between the copper sheets and the cathode external walls is made by means of bolts with the interposition of a conductive and deformable element provided with residual elasticity under compression. The weldings for the assembling of the cathode walls are free from internal stresses.

Abstract: The invention concerns a diaphragm chlor-alkali electrolysis cell comprising a cover, a conductive base for supporting the anodes and a cathode in the form of a box provided with internal wall, external wall and tubular fingers made of a mesh or perforated sheet covered with a porous diaphragm. One or more copper sheets for electric current distribution are fixed to the cathode external walls. The connection between the copper sheets and the cathode external walls is made by means of bolts with the interposition of a conductive and deformable element provided with residual elasticity under compression. The weldings for the assembling of the cathode walls are free from internal stresses.

Abstract: A novel composite membrane comprising a porous substrate of randomly orientated individual fibres and at least one ion conducting polymer, characterised in that the ion conducting polymer is embedded within the porous substrate, a process for its preparation and its use, particularly in fuel cells is disclosed.

Abstract: An electrochemical device for separating oxygen from an oxygen-containing gas comprises a plurality of planar ion-conductive solid electrolyte plates and electrically-conductive gas-impermeable interconnects assembled in a multi-cell stack. Electrically-conductive anode and cathode material is applied to opposite sides of each electrolyte plate. A gas-tight anode seal is bonded between the anode side of each electrolyte plate and the anode side of the adjacent interconnect. A biasing electrode, applied to the anode side of each electrolyte plate between the anode seal and the edge of the anode, eliminates anode seal failure by minimizing the electrical potential across the seal. The seal potential is maintained below about 40 mV and preferably below about 25 mV. A gas-tight seal is applied between the cathode sides of each electrolyte plate and the adjacent interconnect such that the anode and cathode seals are radially offset on opposite sides of the plate.

Abstract: A platinum supported catalyst is disclosed for the anode in a PEM fuel cell with high resistance to poisoning by carbon monoxide. The catalyst contains the noble metals platinum and ruthenium on a finely divided, conductive support material. The two noble metals are not alloyed with each other and are present in highly dispersed form on the support material, wherein the crystallite size of the platinum is less than 2 nm and that of the ruthenium is less than 1 nm.

Abstract: Fluid service and/or electrical conductivity for a fuel cell assembly is promoted. Open-faced flow channel(s) are formed in a flow field plate face, and extend in the flow field plate face between entry and exit fluid manifolds. A resilient gas diffusion layer is located between the flow field plate face and a membrane electrode assembly, fluidly serviced with the open-faced flow channel(s). The resilient gas diffusion layer is restrained against entering the open-faced flow channel(s) under a compressive force applied to the fuel cell assembly. In particular, a first side of a support member abuts the flow field plate face, and a second side of the support member abuts the resilient gas diffusion layer. The support member is formed with a plurality of openings extending between the first and second sides of the support member. In addition, a clamping pressure is maintained for an interface between the resilient gas diffusion layer and a portion of the membrane electrode assembly.

Abstract: Nitric oxide-specific electrodes are useful for in situ detection of nitric oxide in biomedical applications and have at least a surface region thereof which is capable of forming complexes with nitric oxide, for example, nitrosyl complexes. The nitric oxide complexes formed at the surface of the electrodes apparently increase the concentration of nitric oxide available for detection, thereby leading to significantly improved relative responses as compared to other known nitric oxide electrode materials. Most preferably, the electrode has at least an exterior surface region which contains ruthenium and/or at least one oxide of ruthenium. The electrodes are advantageously conditioned in saline solution at +675 mV for about two hours.

Abstract: A sintered laminated structure including a plurality of ceramic layers made of ceramic materials different from one another, wherein each of the ceramic layers is provided with through-holes passing each of the ceramic layers.

Abstract: The present invention provides a bipolar membrane and methods for making and using the membrane. The bipolar membrane comprises a cation-selective region, an anion-selective region, an interfacial region between the anion-selective region and the cation-selective region, and means for delivering fluid directly into the interfacial region. The means for delivering fluid includes passages that may comprise a fluid-permeable material, a wicking material, an open passage disposed within the membrane or some combination thereof. The passages may be provided in many shapes, sizes and configurations, but preferably deliver fluid directly to the interfacial region so that the rate of electrodialysis is no longer limited by the diffusion of fluid through the cation- or anion-selective regions to the interfacial region.

Abstract: The invention provides devices and techniques for reducing or eliminating fuel crossover from the anode to the cathode in fuel cells using organic fuels. The invention particularly provides proton exchange membranes having passages or channels with or without a catalyst layer active for the electrochemical oxidation of a fuel. The invention reduces fuel crossover by providing void spaces within the membrane where the fuel may be sequestered as it diffuses through the membrane from the anode to the cathode. The sequestered fuel may be removed physically and/or electrochemically. The invention provides for physical removal of the sequestered fuel by means of flowing a gas stream or a liquid stream through the passages thus evacuating the fuel before it diffuses to the cathode.

Abstract: An elongate electrode, usually an anode, is provided, suitable for use in an impressed current corrosion protection system. The electrode comprises a central elongate core, usually a metal such as copper, an optional conductive polymeric composition surrounding the metal core and having a higher electrical resistivity than the core, but being in electrical contact with the core, a flexible jacket, for example, a fabric braid containing within it particulate coke, and tensioning wraps positioned around the flexible jacket. The purpose of the tensioning wraps is to compact the coke particles relative to their compaction in the absence of the tensioning wraps.

Abstract: Membrane electrode assemblies are described that include an ion conductive membrane a catalyst adjacent to the major surfaces of the ion conductive membrane and a porous particle filled polymer membrane adjacent to the ion conductive membrane. The catalyst can be disposed on the major surfaces of the ion conductive membrane. Preferably, the catalyst is disposed in nanostructures. The polymer film serving as the electrode backing layer preferably is processed by heating the particle loaded porous film to a temperature within about 20 degrees of the melting point of the polymer to decrease the Gurley value and the electrical resistivity. The MEAs can be produced in a continuous roll process. The MEAs can be used to produce fuel cells, electrolyzers and electrochemical reactors.

Abstract: A process and assembly for stabilizing organic additives in an electrolytic solution while electroplating copper. The process includes forming a protective film on a first surface of an anode and minimizing contact between the electrolytic solution and a second surface of the anode which is further from the cathode than the first surface. An anode housing is used to minimize contact between the electrolytic solution and the second surface of the anode. The housing includes two side walls and a bottom wall, each having a groove, and a sealing back plate. The anode is fitted in the grooves such that the first surface of the anode is in contact with the electrolytic solution and the second surface of the anode abuts against the sealing back plate. The anode housing may be used in an electroplating system including the anode housing, a plating tank containing the electrolytic solution, a cathode immersed in the electrolytic solution, and an anode, which preferably is in the shape of a slab.

Abstract: Metallized cation-exchange membrane The present invention relates to a membrane/electrode composite comprising a membrane comprising a polymeric cation exchanger containing carboxylic acid, phosphonic acid or sulfonic acid groups, which cation exchanger is soluble in a solvent, where on at least one side of the membrane there are applied finely divided metals which catalyze the formation of water from H.sub.2 and O.sub.2. The part of the membrane covered with metal is porous, but contains no closed pores, and the metal can also be present in the pores.

Abstract: Described is a membrane electrode assembly having an ion exchange membrane, and at least two active layers positioned on the same side of the membrane; wherein the active layers containing catalytically-active particles and an ionomer; the average equivalent weights of the ionomers in the layers differ by at least 50; and the active layer positioned closest to the membrane contains the ionomer with the lower average equivalent weight. This membrane electrode assembly, when utilized in a fuel cell, provides a relatively high voltage at a given current density and gas flow rate.

Abstract: A gas-diffusion cathode disposed in contact with an ion-exchange membrane partitioning an electrolytic cell into an anode chamber and a cathode chamber, wherein at least one guide piece is disposed in the gas-diffusion cathode and a salt water electrolytic cell using the above-described gas-diffusion cathode. By using the above-described gas-diffusion cathode for salt water electrolysis, an aqueous caustic alkali solution formed descending in the direction of gravity in the cathode changes direction of movement by contact with a guide piece, whereby the decreased electrode performance resulting from the hindrance of the supply of raw material gas and the discharge of the gas formed caused by the retention of the descending caustic alkali solution is prevented and a large-sized electrolytic cell can be used without problems generally encountered in conventional electrolytic systems.

Abstract: A membrane electrode assembly is provided comprising an ion conducting membrane and one or more electrode layers that comprise nanostructured elements, wherein the nanostructured elements are in incomplete contact with the ion conducting membrane. This invention also provides methods to make the membrane electrode assembly of the invention. The membrane electrode assembly of this invention is suitable for use in electrochemical devices, including proton exchange membrane fuel cells, electrolyzers, chlor-alkali separation membranes, and the like.

Abstract: The invention relates to an electrochemical cell which has an electrode, which may be either an anode or a cathode, and a membrane disposed in contact with one side of the electrode. An anode current bus is disposed on the other side of the anode, and a cathode current bus is disposed on the other side of the cathode. An anode current distributor collects current from the anode current bus and distributes it to the anode by electronic conduction, and a cathode current distributor collects current from the cathode and distributes it to the cathode bus by electronic conduction. The anode or the cathode current distributor is made of a metal which is treated by either nitriding, boriding or carbiding the metal in order to make the metal oxide growth resistant. In particular, the current distributor comprises tantalum that has been nitrided to form Ta.sub.2 N. The current distributor thus provides a barrier between the current bus and the electrode, and the anolyte, catholyte and products of the cell.

Abstract: The invention relates to an electrochemical cell having an electrode with a catalyst layer and a gas diffusion layer. The cell also includes a mass flow field for directing fluid to and away from the electrode. An additional gas diffusion layer is disposed between the gas diffusion layer and the flow field. This increases the diffusion resistance of the fluid. The electrochemical cell of the present invention is particularly useful in a process for electrochemically converting anhydrous hydrogen halide to essentially dry halogen gas, where it is necessary to control and increase limiting current. It is also possible to use the additional gas diffusion layer in an aqueous process electrochemical cell.

Abstract: A porous gas diffusion electrode for membrane fuel cells on an ion-conducting polymer. The electrode contains a finely divided electrocatalyst which is dispersed in a proton-conducting ionomer and has a total porosity of more than 40 to less than 75%. It supplies considerably improved performance data in comparison to known electrodes. The electrode can be produced by using pore-forming materials which are dissolved during the re-protonation of the ion-conducting polymers with sulfuric acid or are decomposed by the action of temperature.

Abstract: The invention relates to an electrochemical cell which has an electrode, a membrane disposed in contact with one side of the electrode and a mass flow field disposed on the other side of the electrode for directing fluid to and away from the electrode. The mass flow field comprises glassy carbon. The cell of the present invention is particularly useful in converting anhydrous hydrogen halide, in particular, hydrogen fluoride, directly to essentially dry halogen gas, such as anhydrous hydrogen fluoride to fluorine gas.

Abstract: A liquid-permeable gas-diffusion cathode adapted for caustic soda electrolysis in contact with an ion-exchange membrane partitioning an electrolytic cell into an anode chamber and a cathode gas chamber. Plural horizontal concave grooves and/or convex portions are provided in an interval with one another on the surface of the gas-diffusion cathode facing the gas chamber. Plural vertical concave grooves may also be provided in an interval on the surface of the cathode crossing the horizontal grooves and/or convex portions. Aqueous caustic soda solution thus formed flows downward along the grooves, etc., without covering other portions of the cathode surface, and is easily released therefrom without clogging perforations in the gas-diffusion layer of the cathode.

Abstract: An electrolyzer including an upright casing having a lower portion formed with a pair of opposed inlet ports and an upper portion formed with a pair of opposed outlet ports, an ion permeable diaphragm mounted within the casing to subdivide the interior of the casing into a pair of reaction chambers respectively in open communication with the inlet and outlet ports, a pair of electrode plates respectively disposed within the reaction chambers and opposed to one another through the diaphragm for electrolyzing water flowing therethrough from the inlet ports to the outlet ports when being applied with electric current, wherein the electrode plates are attached to internal surfaces of the casing to cover each inner end of the inlet ports and to form a pair of bifurcated passages respectively in open communication with the inlet ports, and wherein a pair of inlet chambers are formed along each lower edge of the electrode plates and communicated with the inlet ports through the bifurcated passages.

Abstract: An electrolytic cell for producing sodium hydroxide, etc., which is partitioned by an ion-exchange membrane into an anode chamber and a cathode chamber, wherein at least one of a anode and a cathode is closely contacted to the ion-exchange membrane to form a gas diffusion electrode, and a current supplying means having guides for removing sodium hydroxide, etc., formed at the surface of the gas diffusion electrode is disposed therein closely contacting the gas diffusion electrode.By having a current supplying means having removing guides, sodium hydroxide formed at the surface of the gas diffusion electrode is separated therefrom and removed, whereby the supply of the raw material gas and removal of the produced gas can be smoothly performed without clogging perforations of the gas diffusion electrode with the sodium hydroxide.

Abstract: A process for the regeneration of plastic diaphragms is described, in which a mineral acid solution is mixed with a suitable corrosion inhibitor, this mixture is temperature controlled at from approximately 0.degree. to 100.degree. C., preferably 40.degree. to 80.degree. C., in particular 50.degree. to 70.degree. C., and passed through the diaphragm for from approximately 0.1 to 84 hours, preferably 1 to 72 hours, in particular 2 to 24 hours.

Abstract: Disclosed an electrode for a polymer electrolyte electrochemical cell which comprises catalyst supports carrying catalyst particles, a first solid polymer electrolyte layer insoluble in water and an organic solvent formed on the particles and a second solid polymer electrolyte layer insoluble or soluble in the organic solvent formed on part of the surface of the first solid polymer electrolyte layer and a process of preparing same.

Abstract: The present invention relates to electrode membranes which comprise an ion-exchange material forming a core zone, with electrodes bonded thereto on both sides, the ion exchange material being formed from homopolymers soluble in solvents, or copolymers or mixtures thereof. The polymers must have at least one residue dissociable in ions. The electrode material is connected on either side of the core zone to the ion-exchange material to form an intimate contact between the electrode and the ion exchange materials, while the external sides of the electrode are pure electrode material. The electrode membranes are useful for forming fuel cells or electrolyzers.

Abstract: An improved ink material, particularly for use in printing processes and its use in improved manufacturing processes for higher performance electrodes for application in fuel cells and other electrochemical devices is disclosed.

Abstract: A planar sensor for determining a chemical parameter of a sample, includes a substrate whose surface is at least partly plane and is provided with at least one potentiometric or amperometric and, possibly, an optical transducer, and one or more biochemical components. The transducer and the biochemical component are provided on the surface of the substrate, or at least part of the surface, as a sensor spot, and a cover membrane surrounding this sensor spot, is heat welded to the surface of the substrate. Those sensor spots that include a potentiometric or amperometric transducer are in contact with a strip conductor attached to the plane surface of the substrate and the thermal seal of the cover membrane is interrupted where the conducting strips lead away from the sensor spots.

Abstract: An electrode plate of planar structure contains lamellar electrode elements, with adjacent electrode elements being separated from one another by a gap. For a better escape of the gas from the electrode/membrane area, the lamellar electrode elements are provided with an expanded-metal structure, the openings of which serve to improve the passage of gas. The electrode elements are provided with angled upper edge strips in order to facilitate the escape of gas in the vertical direction. The electrode configuration is particularly suitable as an anodically connected electrode in direct contact with an ion exchanger membrane, but can also be used as a cathode at a distance from the membrane.

Abstract: A high performance ionomer assisted electrolytic cell electrode structure is provided. Such structures operate effectively at catalyst loadings as low as 0.10 mg/cm.sup.2 and demonstrate increased structural integrity without ionomer degradation. The inventive structure comprises a hydrated ion exchange membrane having a first surface and a second surface and at least one catalyst ionomer layer bonded to the first and/or second surface of the membrane that comprises hydrated and swollen ionomer solids bonded to discrete catalyst particles.

Abstract: The invention includes an electrolytic cell for gas-developing or gas-consuming electrolytic reactions and processes, and an electrolysis process therefor. According to the invention, the capillary slit electrode has conduits enabling the separate flow of reaction gas and electrolyte/permeate in the electrode. The electrode is preferably hydrophilic in a narrow internal region for mounting on a separator, while elsewhere it is hydrophobic. Thus electrolyte/permeate penetrates only into the region of the capillary slit electrode near the separator, while the region away from the separator remains free of electrolyte/permeate, so facilitating the unimpeded flow of the reaction gas. The invention is applicable especially in electrolytic cells for chlor-alkali or hydrogen electrolysis, and in the construction of cells for the generation of power.

Abstract: A composite membrane is provided which includes a base material and an ion exchange resin. The base material has a microstructure characterized by nodes interconnected by fibrils, or a microstructure characterized by fibrils with no nodes present. The ion exchange resin substantially impregnates the membrane such that the membrane is essentially air impermeable.

Abstract: The invention provides an improved proton exchange membrane for use in electrochemical cells having internal passages parallel to the membrane surface, an apparatus and process for making the membrane, membrane and electrode assemblies fabricated using the membrane, and the application of the membrane and electrode assemblies to a variety of devices, both electrochemical and otherwise. The passages in the membrane extend from one edge of the membrane to another and allow fluid flow through the membrane and give access directly to the membrane for purposes of hydration.

Abstract: The invention relates to an electrochemical cell which has an electrode, which may be either an anode or a cathode, and a membrane disposed in contact with one side of the electrode. An anode current bus is disposed on the other side of the anode, and a cathode current bus is disposed on the other side of the cathode. An anode current distributor collects current from an anode current bus and distributes it to the anode by electronic conduction, and a cathode current distributor collects current from the cathode and distributes it to the cathode bus by electronic conduction. The anode or the cathode current distributor is made of a metal which is treated by either nitriding, boriding or carbiding the metal in order to make the metal oxide growth resistant. Alternatively, the current distributor on the cathode side may be made of a nickel-based alloy. The current distributor thus provides a barrier between the current bus and the electrode, and the anolyte, catholyte and products of the cell.

Abstract: The invention relates to an electrochemical cell which has an electrode, a membrane disposed in contact with one side of the electrode and a mass flow field disposed on the other side of the electrode for directing fluid to and away from the electrode. The mass flow field comprises glassy carbon. The cell of the present invention is particularly useful in converting anhydrous hydrogen halide, in particular, hydrogen fluoride, directly to essentially dry halogen gas, such as dry fluorine gas. Alternatively, the cell may be used to convert an aqueous reactant.

Abstract: The invention provides fittings for the ends of electrochromatography cols. Each fitting includes an annular electrode surrounding one end of the passage electrical fields to be applied. The fitting also contains a passageway for eluant flowing into or out of the column, an annular chamber for the electrode and a membrane separating the passageway from the annular electrode chamber. The membrane prevents gases and electrolytic products from entering the column eluent going through the chromatographic column. The membrane also isolate the electrodes from the compounds such as proteins and macromolecules being separated. A buffer solution was pumped through the electrode chamber to remove the gases and electrode products. The buffer flow through the electrode chamber maintains a constant pH and conductivity so that the electrical field applied by each electrode is constant. The buffer flow also serves to remove the heat generated in the electrode chamber.

Abstract: An electrode sensor which may be used to specifically and quantitatively measure nitric oxide is provided, as well as a method of preparing and using such an electrode sensor to measure nitric oxide concentration in solution. A nitric oxide (NO) microsensor based on catalytic oxidation of NO comprises a thermally-sharpened carbon fiber with a tip diameter of about 0.5-0.7 .mu.m coated with several layers of p-type semiconducting polymeric porphyrin and cationic exchanger deposited thereon. The microsensor, which can be operated in either the amperometric, voltammetric or coulometric mode utilizing a two or three electrode system, is characterized by a linear response up to about 300 .mu.M, a response time better than 10 msec and a detection limit of about 10 nM. The sensor of the present invention also discriminates against nitrite, the most problematic interferant in NO measurements.