Highly efficient Ni-Sn/Ni foam 3D electrodes for hydrogen production by alkaline electrolysis

Industrial production of Hydrogen by alkaline electrolysis, nowadays implies the use of 3D materials with high specific surface, as electrodes in “zero-gap" electrolyzers. Nickel has been recognized as a non-noble metal suitable as hydrogen evolution reaction (HER) catalyst, and the possibility to produce high porosity Ni foams makes it easily applicable in such industrial systems. In order to increase Ni activity towards HER, Ni-Sn alloys have been electrodeposited onto open pore structure Ni foams with different pore sizes (450-1200 µm), since these alloys have demonstrated excellent HER activity. Such prepared electrodes have been tested in 1 M KOH in laboratory conditions at first, but their scale up and application in “zero-gap" pilot systems are the main goal of the international cooperation project between Germany and Western Balkan countries, “Innovative Coated Porous Electrodes for High-Scale Hydrogen Production" (NOVATRODES). In comparison to bare Ni foams, Ni-Sn/Ni foam electrodes have demonstrated a decrease in overvoltage of around 400 mV at -200 mA cm-2 in 1 M KOH at гоom temperature, in a three-compartment electrochemical cell. Scanning Electron Microscopy and Energy Dispersive X-ray Spectroscopy analysis have shown that NiSn coating is present at all available Ni foam surface - at outer electrode surface as well as inside the pores, with quite homogenous composition. This result, very significant for use in “zero-gap" systems, as well as excellent activity of Ni-Sn/Ni foam electrodes, has led to the first scale up phase - testing in 30% KOH at 70 °C, in an “H"-type cell with membrane, and these tests have shown a remarkably low overpotential, below the threshold set by the project objectives.