Engineering a novel interface structure on La0.75Sr0.25Cr0.5Mn0.5O3-δ-Gd0.1Ce0.9O2-δ fuel electrode with excellent electrochemical performance and sulfur tolerance for electrocatalytic CO2 reduction

Surface and interface engineering as an efficient and controllable strategy in designing electrode structure has been widely investigated for achieving high catalyst activity and durability of robust electrodes in solid oxide cells (SOCs). The constructed heterojunction structures favor expedited charge transfer and promote the catalytic reaction. Anti-coking La0.75Sr0.25Cr0.5Mn0.5O3-δ (LSCM)-based fuel electrodes are considered as promising candidates for alternative Ni-based cermet electrodes in solid oxide electrolysis cell (SOEC), however, they suffer from insufficient electrocatalytic activity for CO2 electrolysis. Herein, Mn-containing Pr0.6Sr0.4FeO3-δ (Pr0.6Sr0.4Fe0.8Mn0.2O3-δ, PSFM) nanoparticles with excellent catalyst activity are synthesized and epitaxially grown on the surface of LSCM via infiltration technique. The spontaneous connected interface can provide direct tunnel for oxygen ion and electron transport along the (110) plane of LSCM. Meanwhile, this interface promotes an increase in oxygen vacancies and enhances both surface oxygen exchange and bulk oxygen diffusion capacities. These improvements are advantageous for CO2 adsorption and carbonate dissociation at three phase boundaries (TPBs), leading to a significant enhancement in the kinetics of CO2 reduction reaction. The electrolyte-supported single with PSFM/La0.75Sr0.25Cr0.5Mn0.5O3-δ-Gd0.1Ce0.9O2-δ (LSCM-GDC) fuel electrode exhibits an impressive current density of 1.09 A cm−2 at the applied voltage of 1.5 V and 800 °C, which increases by approximately 336 % than that of LSCM-GDC. In addition, the atomic arrangement enables in-situ formation of PSFM by trapping of surface Sr/Mn atoms on the LSCM surface, avoiding Sr segregation and enhancing the resistance to sulfur poisoning. This study demonstrates a strategy for achieving the enhanced CO2 electrolysis performance and sulfur tolerance by engineering highly active interface. •LSCM-GDC coated with PSFM NPs exhibits excellent CO2 electrolysis performance.•PSFM possesses high electron conductivity, excellent Kchem and Dchem.•PSFM NPs are epitaxial grown on the LSCM-GDC surface by infiltration technology.•The novel interface facilitates the oxygen ion/electron transport.•PSFM/LSCM-GDC single cell shows impressive stability in CO2-SO2 condition (20 ppm).