Electrochemical process for the production of pressurized gaseous hydrogen by electrolysis then by electrochemical conversion

An electrochemical process for the production of pressurized gaseous hydrogen, characterized in that it consists essentially of implementing, in a decoupled manner, at least one step of electrolysis of an electrolyte, this electrolysis step producing gaseous oxygen in a chamber , and at least one step C° of electrochemical conversion of H+ ions into gaseous hydrogen in a chamber C° which is identical to or different from chamber and which contains a liquid phase L and a gas phase G not dissolved in this liquid phase;

• wherein:
• when chamber and C° are identical, decoupled steps and C° are performed in a chamber C°;
• the chamber C° and/or C° comprises at least one electrode;
• the electrolysis step involves at least one cathode on which at least one ionic species is electrochemically reduced;
• the gaseous hydrogen produced in the conversion step C.° is partly present in the gaseous headspace of chamber C°, as bubbles in the electrolyte;
• and partly dissolved in the electrolyte which is thus supersaturated;
• with hydrogen;
• the electrolyte comprises at least one redox pair (A/B) forming at least one intermediate vector enabling the decoupling of steps & C°, acidic electrolyte:
• Eth(A/B)<Eth(O2/H2O);
• |Δ[Eth(A/B)−Eth(O2/H2O)]≥100 mV
• basic electrolyte:
• Eth(A/B)<Eth(O2/H2O);
• |Δ[Eth(A/B)−Eth(O2/H2O)]≥100 mV
• the interface between the undissolved gas phase G and the liquid phase L—hereinafter referred to as the G/L interface—is increased at least during step C°, so as to accelerate the diffusion, from the liquid phase to the gas phase, of the dissolved hydrogen able to supersaturate the electrolyte;
• and the pressurized gaseous hydrogen is collected in a storage tank.