Catalytic Performance of B-Site Doped LST Modified NiO/YSZ Cathodes for CO₂ Reduction in a Solid Oxide Electrolyzer

The NiO/YSZ modified with B-site doped lanthanum strontium titanate (LST) was investigated as cathode materials for the reduction of CO 2 in a solid oxide electrolysis cell (SOEC). The electrocatalytic activity evaluated in CO 2 /H 2 under solid oxide fuel cell and SOEC conditions both demonstrated that the cobalt-doped LST (LSTC) performs better than pristine NiO/YSZ and is the best among the doped LSTs. The high performance of the LSTC-modified cathode was ascribed to its good CO 2 reduction ability, as evidenced by infrared and temperature-programmed surface reaction studies. Furthermore, LSTC was believed to play a role not only in serving active sites for the CO 2 reaction, but also in relieving stress induced by Ni oxidation, thus stabilizing the cathode structure. Direct electrolysis in the absence of H 2 further confirmed that the LSTC modified cell exhibits better performance. On the contrary, the other LST-modified cells and a CaO-modified one suffered from severe electrode polarization. These results present the potential to construct a cell combining B-site doped LST oxides with Ni cermet in a SOEC for energy conversion.