How to make an electrochemical device that produces hydrogen and electricity from metals?

— FLOW CELL AND SEMI-SOLID ELECTRODE —

By milling a metal piece in small metal particles (1), a semi-solid electrode in the form of a slurry can be formed. This slurry can be pumped into an electrochemical flow cell to pass through the channel of the flow field of the electrode (2). The metal particles in the slurry are separated from the acid in the channel (7) by a membrane. That membrane (3) is an anion exchange membrane that prevents the protons from the acid to cross the membrane. The porous electrode (5) in contact with the acid in the channel (7) is functionalized by a catalytic layer (4) promoting the hydrogen evolution reaction. 

On the left hand side, the metal particles are oxidized into soluble metal cations; while electrons are reaching the external circuit by the electrode (2). On the right hand side, the protons is reduced to hydrogen gas transported in the acid solution. The anions from the acid crosses the membrane to compensate the charges of the metal cations. Such a electrochemical flow cell has actually some resemblance with classical electrolysers already on the market (see 3D-sketch below), but the fluids are different and the concept totally new.

In principle every metals that would react with an acid to produce hydrogen could be used in the form of a slurry in this device. For instance, iron and zinc particles. The advantage with this device is that large quantity of metal particles can be used to produce a continuous flow of hydrogen gas. In the same time, a continuous electrical power is generated. Those cells can be put in series like in industrial fuel cells to increase the output voltage. Now, we could imagine to put this device into a large energy system with various key elements.