| Abstrakt: |
High temperature steam (H2O) electrolysis via a solid oxide electrolysis cell is an efficient way to produce hydrogen (H2) because of its high energy conversion efficiency as well as simple and green process, especially when the electrolysis process is combined with integrated gasification fuel cell technology or derived by renewable energy. However, about 60%–70% of the electricity input is consumed to overcome the large oxygen potential gradient but not for electrolysis to split H2O to produce H2 due to the addition of safe gas such as H2 in the fuel electrode. In this work, Sr2Fe1.5Mo0.5O6-δ-Ce0.8Sm0.2O1.95 (SFM-SDC) ceramic composite material has been developed as fuel electrode to avoid the use of safe gas, and the open circuit voltage (OCV) has been effectively lowered from 1030 to 78 mV when the feeding gas in the fuel electrode is shifted from 3%H2O–97%H2 to 3%H2O–97%N2, reasonably resulting in a significantly increased electrolysis efficiency. In addition, it is also demonstrated that the electrolysis current density is greatly enhanced by increasing the humidity in the fuel electrode and the working temperature. A considerable electrolysis current density of − 0.54 A/cm2 is obtained at 800 °C and 0.4 V for the symmetrical electrolyzer by exposing SFM-SDC fuel electrode to 23%H2O–77%N2, and durability test at 800 °C for 35 h demonstrates a relatively stable electrochemical performance for steam electrolysis under the same operation condition without safe gas and a constant electrolysis current density of − 0.060 A/cm2. Our findings achieved in this work indicate that SFM-SDC is a highly promising fuel electrode for steam electrolysis. [ABSTRACT FROM AUTHOR] |
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