Abstract: An active portion of a nano-size element is selectively destroyed by applying an electric potential to the nano-size element having a carbon network structure of carbon as an outer shell while immersed in an electrolytic solution. For example, an electric potential of 1.20 to 1.60 V (RHE) is applied to the carbon nanotubes in electrolytic solution so as to oxidize the active portion in each carbon nanotube and to thereby selectively remove the ends. Consequently, an open end is created in the carbon nanotube.

Abstract: According to this invention, an active portion in nano-size substance is destroyed selectively by applying an electric potential to the nano-size substance having a network structure of carbon at an outer shell thereof in electrolytic solution. For example, an electric potential of 1.20 to 1.60 V (RHE) is applied to carbon nanotube in electrolytic solution so as to oxidize the active portion in the carbon nanotubes selectively and remove the ends of them. Consequently, an open end is created in the carbon nanotube.

Abstract: A CO gas sensor is equipped with a detecting unit in which a solid electrolyte membrane is held between a detection electrode and a counter electrode, and a voltage applying unit which applies voltage between the detection electrode and the counter electrode and changes the voltage. The detection electrode includes an electrochemically active first catalyst in an electrically conductive porous body, a reaction layer having a density of 1 ng/cm2-100 &mgr;g/cm2 and having a thickness of 0.3 nm-15 &mgr;m, and the counter electrode includes an electrochemically active second catalyst carried on an electrically conductive porous body.

Abstract: There is provided a concentration sensor for measurement of concentrations of one or plural target substances in a system, with a detection electrode of conductive diamond. The measuring method with the concentration sensor involves measuring the reaction potentials of plural target substances in a sample containing and determining the concentrations of the plural substances by use of the difference between the resulting reaction potentials of the respective substances. The measuring method can also determine the concentration of a single substance in a sample containing one kind of target substance.

Abstract: A CO gas sensor according to the present invention includes a gas collecting container for collecting a measured gas therein; a detecting section provided within the gas collecting container and having at least a pair of electrodes positioned through electrolyte; and a voltage applying apparatus for applying voltage to the detecting section. One of the electrodes of the detecting section is a detection electrode having the capability of adsorbing at least one of hydrogenous gas and CO gas when a voltage is applied and then oxidizing it. By introducing a measured gas into a gas collecting container of the CO gas sensor and carrying out electrolysis according to a potential sweep method or a pulse method with the measured gas being in contact with the detecting section, a CO gas concentration in the measured gas can be measured based on an electrical current value obtained at the detecting section and changes of the electrical current with elapse of time.

Abstract: There are provided a gaseous-diffusion electrode which can exhibit sufficient gas-supplying ability and gas-discharging ability and an excellent durability even when partly immersed in an electrolysis solution; and an electrochemical reactor using the gaseous-diffusion electrode. A porous membrane 15 which is permeable to gas but not to an electrolysis solution is fixed to the surface of the gaseous-diffusion layer 13 of a gaseous-diffusion electrode 11 obtained by joining a reaction layer 12 supporting a catalyst metal and a gaseous-diffusion layer 13 to each other, so as to cover the surface of the gaseous-diffusion layer 13. When a gas passageway member 17 serving as gas passageway to the gaseous-diffusion layer 13 is inserted between the surface of the gaseous-diffusion layer 13 and the porous membrane 15, the gas-supplying ability and the gas-discharging ability becomes greatly improved.