An already well-developed and cost-effective green technology for hydrogen production is alkaline water electrolysis, in which hydrogen gas is produced from the water splitting reaction under alkaline conditions . In alkaline electrolyzers the anode and the cathode are immersed in highly concentrated alkaline solutions (e.g., NaOH or KOH). These electrodes are separated by a porous and electrically insulating separator material, which is filled with a highly ionically conducting medium for hydroxide ions (OH -) transport from cathode to anode.