Abstract: The invention is based on the preparation of an organic solution of preferably phosphonic acids and tetravalent metals salts, preferably of Zr, Ti, Sn and Ce, in organic solvents, which behaves as a solution of layered tetravalent metals salts, preferably phosphate-phosphonates, which are completely insoluble in the known solvents. This peculiarity allows an easy insertion of particles of the above compounds in the pores of porous membranes, in the matrices of those polymers, which are soluble in the same organic solvents, as well as in the membrane/electrode interfaces of fuel cells. The use of tetravalent metals salts, preferably zirconium phosphate-phosphonates, possessing high proton conductivity (in some cases higher than 10?1 S cm?1) allows the preparation of impregnated porous membranes and of nano-polymeric membranes combining good mechanical properties, and/or reduced permeability to gaseous species, with good proton conductivity.

Abstract: The invention is relative to a membrane-electrode assembly for fuel cells, comprising a state of the art ion-exchange polymeric membrane and state of the art gas diffusion electrodes, whose electrochemical properties are modified through the addition of a hydrophilic component localized in correspondence to one or both the electrodic interfaces and/or one or both the external surfaces of the membrane. The modified membrane-electrode assembly is characterized by high protonic conductivity and high efficiency even in the presence of small quantities of carbon monoxide, or of other contaminants contained in the fuel, even at temperatures as low as 100° C., being also suitable for medium temperature (100–160° C.) operation at relative humidity level lower than saturation.

Abstract: The invention provides composite membrane materials comprising a polymer of the state of art uniformly filled with a zirconium phosphate, preferably ?-zirconium phosphate or zirconium phosphate sulfoarylenphosphonate particels. The composite membrane materials are preferably prepared starting from a solution of a polymer of the state of art and from a colloidal dispersion of ?-zirconium phosphate or a zirconium phosphate sulfoarylenphosphonate. The colloidal particles are transferred into the solution of the polymer preferably by mixing the dispersion with the solution or by means of phase transfer. The membrane material is preferably obtained by removing the solvent by evaporation or by a suitable non-solvent.

Abstract: The invention is based on the preparation of an organic solution of preferably phosphonic acids and tetravalent metals salts, preferably of Zr, Ti, Sn and Ce, in organic solvents, which behaves as a solution of layered tetravalent metals salts, preferably phosphate-phosphonates, which are completely insoluble in the known solvents. This peculiarity allows an easy insertion of particles of the above compounds in the pores of porous membranes, in the matrices of those polymers, which are soluble in the same organic solvents, as well as in the membrane/electrode interfaces of fuel cells. The use of tetravalent metals salts, preferably zirconium phosphate-phosphonates, possessing high proton conductivity (in some cases higher than 10?1 S cm?1) allows the preparation of impregnated porous membranes and of nano-polymeric membranes combining good mechanical properties, and/or reduced permeability to gaseous species, with good proton conductivity.

Abstract: The invention provides composite membrane materials comprising a polymer of the state of art uniformly filled with a zirconium phosphate, preferably ?-zirconium phosphate or zirconium phosphate sulfoarylenphosphonate particels. The composite membrane materials are preferably prepared starting from a solution of a polymer of the state of art and from a colloidal dispersion of ?-zirconium phosphate or a zirconium phosphate sulfoarylenphosphonate. The colloidal particles are transferred into the solution of the polymer preferably by mixing the dispersion with the solution or by means of phase transfer. The membrane material is preferably obtained by removing the solvent by evaporation or by a suitable non-solvent.

Abstract: The invention is relative to a membrane-electrode assembly for fuel cells, comprising a state of the art ion-exchange polymeric membrane and by state of the art gas diffusion electrodes, whose electrochemical properties are modified through the addition of a hydrophilic component localized in correspondence of one or both the electrodic interfaces and/or one or both the external surfaces of the membrane. The such modified membrane-electrode assembly is characterised by high protonic conductivity and high efficiency even in the presence of small quantities of carbon monoxide, or of other contaminants contained in the fuel, even at temperatures as low as 100° C., being also suitable for medium temperature (100-160° C.) operation at relative humidity level lower than saturation.

Abstract: Solid mesoporous crystalline composition of a pyrophosphate-phosphate of a tetravalent metal, with a high surface area and narrow distribution of the mesopores, having formula (I):M(P.sub.2 O.sub.7).sub.1-z (HPO.sub.4).sub.2z (I)wherein: M is a tetravalent metal and z varies from 0.05 to 0.25.The process for its production is described together with its uses.

Abstract: A solid-state sensor for determining the concentration of gases which can react with hydrogen, in particular, of oxygen, which includes a solid-state proton conductor into contact: on the one side, with a reference electrode, constituted in its turn by a metal hydride or a metal alloy, and on the other side with an electrode which catalyses the reaction of the gas to be detected, with said sensor being connected with a power feed system which supplies current or voltage impulses, and with a system which detects the value of potential after each impulse.