Electrochemical Characterization of a Solid Oxide Membrane Electrolyzer for Production of High-Purity Hydrogen

Abstract

A laboratory-scale solid oxide membrane (SOM) steam electrolyzer that can potentially use energy value in waste or any source of carbon or hydrocarbon to produce high-purity hydrogen has been fabricated and evaluated. The SOM electrolyzer comprises an oxygen-ion-conducting yttria-stabilized zirconia (YSZ) electrolyte with a Ni-YSZ cermet cathode coated on one side and liquid-metal anode on the other side. The SOM electrolyzer is operated at 1000°C by providing a steam-rich gas feed to the Ni-YSZ cermet cathode and feeding a reductant source into the liquid-metal anode. The steam is reduced over the cathode, and oxygen ions are transported through the YSZ electrolyte and are oxidized at the molten metal electrode by the reductant feed. The advantage of SOM electrolyzer over the state-of-the-art solid oxide electrolyzer is its ability to use solid, liquid, and gaseous reductant feed in the liquid-metal anode to reduce the oxygen chemical potential and drive the reaction for hydrogen production. In this study, an electrochemical process model for a SOM electrolyzer was developed. The condition of the liquid-metal anode with reductant was simulated by bubbling humidified hydrogen (3 pct H 2 O) in the liquid metal, and the electrochemical performance of the SOM electrolyzer was modeled. The experimental data were curve-fitted into the model to identify the various polarization losses. It showed that the performance of the SOM electrolyzer was dominated by the ohmic resistance of the YSZ membrane. Based on the results of this study, future work is needed toward increasing the performance efficiency of the SOM electrolyzer.

Solid Oxide Membrane Electrolysis Process for Aluminum Production: Experiment and Modeling

“…For small currents where there is little mass-transfer effects, η ct(a.c) is described by the Butler-Volmer equation: 17,[37][38][39] …”

“…Activation polarization.-The activation polarization η ct(a.c) is the overpotential required to overcome the activation energy barrier for the charge transfer reactions at the electrodes. For small currents where there is little mass-transfer effects, η ct(a.c) is described by the Butler-Volmer equation: 17,[37][38][39]…”

Energy-Efficient and Environmentally Friendly Solid Oxide Membrane Electrolysis Process for Magnesium Oxide Reduction: Experiment and Modeling

“…The additional potential needed to overcome the activation energy barrier for the charge transfer reactions at the electrode/electrolyte interface is called activation polarization, g act . For small currents and/or rapid mass transfer, it is related to the cell current i by the following Butler-Volmer equation [28][29][30] :…”

“…[3] can be rearranged into Eq. [28] to write R e(flux) as a function of R MgO iðfluxÞ and t e(flux) .…”

Novel-CdS-nanorod with stacking fault structures: Preparation and properties of visible-light-driven photocatalytic hydrogen production from water

“…Over the past decades, major breakthroughs have been made for efficient photocatalytic hydrogen production from water [1][2][3][4][5][6], since Fujishima and Honda reported direct photoelectrochemical water splitting on a TiO 2 photoelectrode [7]. However, most photocatalysts can only respond to ultraviolet light (ultraviolet light occupies around 4% in the solar spectrum), and their activities for photocatalytic hydrogen production were relatively low.…”