Elevated-temperature bio-ethanol-assisted water electrolysis for efficient hydrogen production

Abstract

Steam electrolysis over solid oxide electrolysis cells (SOECs) is a promising technique to store renewable power (such as solar and wind power) into hydrogen, and bio-ethanol-assisted steam electrolysis not only increases energy conversion efficiency but also store bio-mass energy into valuable fuels. This study developed SOEC-type reactors for conducting ethanol-assisted water electrolysis for the first time. Conventional catalytic steam reforming of ethanol for hydrogen production consumes a lot of heat and includes a complicated process, while the ethanol-assisted water electrolysis can achieve thermoneutral operation at the electrolysis potential of 0.36 V and generate heat at the electrolysis potentials of above 0.36 V, simultaneously obtaining pure hydrogen from cathode chamber by one step. Micro-reformer constructed by loading fibrous catalysts within channeled anode supports performed efficient ethanol reforming to facilitate fuel oxidation on anode and hence promote steam electrolysis on cathode. Employing Ni-based materials for both anode and cathode enables the co-sintering of three layers of SOEC components, resulting in low cell resistances and stable electrolysis at a record high current density of 3.0 A cm−2 under a low overall cell voltage of less than 1.3 V. Therefore, this study has demonstrated an efficient way to generate green hydrogen energy from renewables.