Abstract: There are disclosed a nitrogen oxide removal catalyst comprising palladium fixed on at least one metal oxide selected from the group consisting of titanium oxide, aluminum oxide, zinc oxide, and magnesium oxide, and a method for removing nitrogen oxides, comprising bringing a nitrogen oxide-containing gas into contact with the above-mentioned catalyst in the presence of hydrogen.

Abstract: A method for the production of a gas diffusion electrode having particles of a platinum group metal deposited on a carbon sheet is disclosed. This method comprises placing a water-repelling carbon sheet into contact with ozone, thereby oxidizing the surface of the sheet and forming a functional group on the surface, then immersing the sheet in a solution containing platinum group metal complex cations as dissolved seeds, thereby inducing ion exchange between the hydrogen ions present in the functional group and the platinum group metal complex cations and deposition of the platinum group metal complex cations on the carbon sheet, and further reducing the platinum group metal complex cations on the carbon into platinum group metal particles.

Abstract: An actuator element comprises an ion exchange membrane and a pair of electrodes attached to opposite surfaces of the ion exchange membrane; the ion exchange membrane in a water-containing state being caused to bend and/or deform by application of an electric potential difference thereacross.

Abstract: Disclosed is a method for the manufacture of an ion-exchange membrane--catalytic metal composite, which comprises treating the surface of an ion-exchange membrane with a low-temperature gas plasma to thereby form micropores on the membrane surface, and with or without subjecting the ion-exchange membrane to a hydrothermal treatment at 100.degree.-200.degree. C., then attaching a catalytic metal onto the ion-exchange membrane.