Comprehensive understanding of alkaline-earth elements effects on electrocatalytic activity and stability of LaFe0.8Ni0.2O3 electrode for high-temperature CO2 electrolysis

Unlocking the Potential of A-Site Ca-Doped LaCo0.2Fe0.8O3−δ: A Redox-Stable Cathode Material Enabling High Current Density in Direct CO2 Electrolysis

“…R Ohmic and R p values at 800 °C in Figure 8d are found to be 0.14 and 0.18 Ω cm 2 , respectively. When compared with previously reported cathodes for CO 2 electrolysis, LCCF64 demonstrates much lower R p values at 800 °C, e.g., La 0.6 Ca 0.4 Fe 0.8 Ni 0.2 O 3 (0.737 Ω cm 2 ), La 0.6 Ba 0.4 Fe 0.8 Ni 0.2 O 3 (2.124 Ω cm 2 ), La 0.6 Sr 0.4 Fe 0.8 Ni 0.2 O 3 (1.432 Ω cm 2 ), 26 La 0.6 Sr 0.4 FeO 3 (1.31 Ω cm 2 ), 54 and La 0.6 Sr 0.4 Fe 0.95 Mo 0.05 O 3 (5.8 Ω cm 2 ). 55 Furthermore, the performance of CO 2 electrolysis from symmetrical cells with the cell configuration of LCCF64// LSGM//LCCF64 was also evaluated.…”

“…26,29−31 For instance, Ca-doped La 0.6 A 0.4 Fe 0.8 Ni 0.2 O 3 exhibited superior electrochemical performance compared to Sr/Ba-doped materials due to its appropriate conductivity, suitable oxygen vacancy concentration, and high catalytic activity for CO 2 RR. 26 Additionally, La 0.6 Ca 0.4 Fe 0.8 Ni 0.2 O 3−δ was examined as a symmetrical SOEC electrode for CO 2 electrolysis, achieving a current density of 1.41 A cm −2 at 2.0 V with direct CO 2 electrolysis at 800 °C. Interestingly, it has been demonstrated that the La 0.6 Ca 0.4 Fe 0.8 Ni 0.2 O 3−δ electrodes could be easily restored through air treatment after CO 2 electrolysis operation to prevent carbonate formation.…”

“…Previous studies have indicated that perovskite oxide materials having Ca-doped on the A-site are less susceptible to carbonation when exposed to a CO 2 containing atmosphere than those Sr- or Ba-doped materials. ,, For example, Song et al investigated La 0.6 A 0.4 FeO 3−δ (A = Ca, Sr, and Ba) as oxygen ion conductor materials, and they found that La 0.6 Ca 0.4 FeO 3−δ are less vulnerable toward carbonation upon exposure to CO 2 when compared with Sr/Ba-doped ones . Similarly, when Ca-doped LaFeO 3 perovskite was studied as a cathode material in solid oxide fuel cells, both the experimental and DFT calculation results confirmed that La 0.6 Ca 0.4 FeO 3−δ exhibited better CO 2 tolerance than the materials without Ca .…”

Oxygen activation on Ba-containing perovskite materials

“…Transition metals, such as Mn, Fe, Co, and Ni, in the B-sites of perovskite-type oxides (ABO 3− ) are generally considered as active sites because both the mixed valence states of the transition metals and medium B─O bond length are favorable for oxygen activation (12)(13)(14)(15)(16)(17)(18). However, the segregation of alkaline earth elements, i.e., Ba, Sr, and Ca, in the A-sites of perovskites and double perovskites in an oxygen-enriched atmosphere has been widely reported (19)(20)(21)(22)(23)(24)(25)(26). The degradation of electrode catalytic activity was even suggested to closely correlate to the segregation of alkaline earth elements on perovskite surfaces (22)(23)(24)(25)(26).…”

“…However, the segregation of alkaline earth elements, i.e., Ba, Sr, and Ca, in the A-sites of perovskites and double perovskites in an oxygen-enriched atmosphere has been widely reported (19)(20)(21)(22)(23)(24)(25)(26). The degradation of electrode catalytic activity was even suggested to closely correlate to the segregation of alkaline earth elements on perovskite surfaces (22)(23)(24)(25)(26). The segregation tendency of alkaline earth elements is directly related to cationic size (27,28).…”