Abstract: An electrochemical process comprises a step El of electrolysis of an electrolyte in order to produce gaseous oxygen and a step of converting oxidation-reduction chemical energy into electrical energy with production of H2. The electrolyte comprises Mm+ ions of a metal M corresponding to the redox pair (Mm+/M), and Aa+ ions of a depolarization additive A corresponding to a redox pair (Aa+/A). Current is supplied between the anode and the cathode, Aa+ and Mm+ are deposited on the cathode respectively in the form of A and M during the electrolysis and gaseous oxygen is released at the anode. The supply of current between the anode and the cathode is then cut off. Depolarization occurs corresponding to the conversion step C°, with production of H2 and dissolution of M and A into Mm+ and Aa+ at the electrode acting as the cathode during step El and the produced H2 is collected.

Abstract: A reinforced gelled capsule comprising a solvent, in which are distributed in a homogeneous manner nano-objects, and/or sub-micron objects, and/or nanostructures, coated with macromolecules of polysaccharide(s), the said macromolecules forming, in at least one part of the capsule, a gel by cross-linking with the cations of at least one element, and in which the external surface of the capsule is covered with crystals made of hydroxide of said element. A method for preparing the reinforced, gelled capsule. A reinforced, lyophilised, gelled capsule, prepared by means of lyophilisation, then followed by exposure to a gas containing carbon dioxide, of the said reinforced, gelled capsule and method of preparation thereof.