Électrodes 3D pour la production électrochimique d'hydrogène à grande échelle

Details

Supervisors

Proost, Joris

Faculty

Ecole polytechnique de Louvain

Degree label

Master [120] : ingénieur civil en chimie et science des matériaux

Abstract

enHydrogen nowadays represents one of the most promising way to respond environmental issues because it can be used as a fuel for vechicles (buses, cars,...) but also to store residual electricity produced by intermittent sources of energy as the wind or the sun. Using green electricity to produce hydrogen from water is actually the most sustainable way to fulfill these functions. The objective pursued in this master thesis is to study the electrochemical behaviour of an electrolytic cell in which 3D electrodes formed of metallic foams are used in order to increase the overall reactional surface which is in fact the electrolyte-electrode interface. By doing so, lowering current densities and improving mass transfer are expected. Pumps with adaptative flows are used to feed in electrolyte the Micro Flow Cell used to realize different experiments on water electrolysis process. The electrolyte will be a solution of 1M ce{KOH} so the process is performed in an alkaline medium with a pH of 14. The metallic foams with different pores diameters and thus different specific areas are made of nickel which proves to be a good and especially cheap electrocatalyst. A cyclic voltammetry have been implemented to sweep the potential and measure the current which is the electrical representation of the gases production while a galvanostatic procedure allows to calculate the faradaic yield of the cell. From galvanostatic procedures, it has been measured that the faradaic yield for hydrogen production is close to 100% which shows a good behaviour of nickel foams as electrocatalyst. The potential necessary to maintain the current during these procedures has prooved to be lower when 3D electrodes have been mounted both in the cathodic and anodic compartments compared to the use of simple 2D electrodes/plates. The electrical consumption is thus reduced. The cyclic voltammetries realized at different flows show that for a configuration in which the foams are only used in the cathodic side, none significative fluxes dependance has been observed for any pores diameters. On the other hand, increasing both cathodic and anodic flows exhibits an important enhancement of the current value (and thus hydrogen production) in a configuration in which foams with small pores diameters are used on both sides. Raising the cathodic flux brings to the highest increase in current