Abstract: An electrochemical process implements, in a decoupled manner, a first step of electrolysis of an electrolyte to produce gaseous oxygen in a chamber and a second step of electrochemical conversion of H+ ions into gaseous hydrogen in a chamber which contains a liquid phase and a gas phase not dissolved in the liquid phase. Gaseous hydrogen produced in the conversion step is partly present in the gaseous headspace of chamber and as bubbles in the electrolyte, and partly dissolved in the electrolyte which is saturated with hydrogen. The electrolyte has at least one redox pair (A/B) forming at least one intermediate vector enabling the decoupling of the first and second steps. The interface between the gas and liquid phases is increased during the second step to accelerate the diffusion, from liquid phase to gas phase, of the dissolved hydrogen able to supersaturate the electrolyte. Pressurized gaseous hydrogen is then collected.

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: An electrochemical process implements, in a decoupled manner, a first step of electrolysis of an electrolyte to produce gaseous oxygen in a chamber and a second step of electrochemical conversion of H+ ions into gaseous hydrogen in a chamber which contains a liquid phase and a gas phase not dissolved in the liquid phase. Gaseous hydrogen produced in the conversion step is partly present in the gaseous headspace of chamber and as bubbles in the electrolyte, and partly dissolved in the electrolyte which is saturated with hydrogen. The electrolyte has at least one redox pair (A/B) forming at least one intermediate vector enabling the decoupling of the first and second steps. The interface between the gas and liquid phases is increased during the second step to accelerate the diffusion, from liquid phase to gas phase, of the dissolved hydrogen able to supersaturate the electrolyte. Pressurized gaseous hydrogen is then collected.