Fe-Doped Ceria-Based Ceramic Cathode for High-Efficiency CO2 Electrolysis in Solid Oxide Electrolysis Cell.

In the quest for sustainable energy solutions, solid oxide electrolysis cell (SOEC) emerges as a key technology for converting CO2 into fuels and valuable chemicals. This work focuses on pure ceramic Fex Sm0.2 Ce0.8 O2- δ (xFe-SDC) as the fuel electrodes, and Sr-free ceria-based ceramic electrodes can be successfully constructed for x ≤ 0.05. The incorporation of Fe into the ceria lattice increases the oxygen vacancy concentration and promotes the formation of catalytic sites crucial for the CO2 reduction reaction (CO2 RR). Density functional theory calculations indicate that Fe enhances electrochemical performance by decreasing the CO2 RR energy barrier and facilitating oxygen ion diffusion. At 800 °C and 1.5 V, single cells with 0.05Fe-SDC cathodes manifest attractive performance, attaining current densities of -1.98 and -2.26 A cm-2 under 50% CO2 /CO and pure CO2 atmospheres, respectively. These results suggest the great potential of xFe-SDC electrodes as promising avenues for high-performance fuel electrodes in SOEC.

A Superior Catalytic Air Electrode with Temperature-Induced Exsolution toward Protonic Ceramic Cells.

Protonic ceramic cells merit extensive exploration, attributed to their innate capabilities for potent and environmentally benign energy conversion. In this work, a temperature-induced exsolution methodology to synthesize SrCo0.5Nb0.5O3-δ (SCN) nanoparticles (NPs) with notably elevated activity on the surface of PrSrCo1.8Nb0.2O6-δ (PSCN) is proposed, directly addressing the extant challenge of restrained catalytic activity prevalent in air electrode materials. In situ assessments reveal that SCN NPs commence exsolution from the matrix at temperatures surpassing 900 °C during straightforward calcination processes and maintain stability throughout annealing. Notably, the resultant SCN-PSCN interface facilitates vapor adsorption and protonation processes, which are poised to enhance surface reaction kinetics pertaining to the proton-involved oxygen reduction and evolution reaction (P-ORR and P-OER). A fuel-electrode-supported protonic ceramic cell leveraging SCN-PSCN as the air electrode manifests compelling performance, attaining a peak power density of 1.30 W·cm-2 in the fuel cell modality and a current density of 1.91 A·cm-2 at 1.3 V in the electrolysis mode, recorded at 650 °C. Furthermore, density functional theory calculations validate that the introduction of SCN NPs onto the PSCN surface conspicuously accelerates electrode reaction rates correlated with P-ORR and P-OER, by significantly mitigating energy barriers associated with surface oxygen and vapor dissociation.

Fe-Doped SDC Solid Solution as an Electrolyte for Low-to-Intermediate-Temperature Solid Oxide Fuel Cells.

Ceria-based oxides, such as samaria-doped ceria (SDC), are potential electrolytes for low-to-intermediate-temperature solid oxide fuel cells (SOFCs). The sinterability of these materials can be improved by adding iron as the sintering aid. This work reveals that Fe is soluble in SDC, forming an Fe-doped SDC solid solution. It is found that the solubility is affected by the sintering temperature. Fe doping has obvious effects on electrolyte properties, including sintering characteristics, thermal expansion behaviors, and electrical conductivities in both air and hydrogen atmospheres. The conductivity obviously increases while the activation energy decreases by doping Fe. Compared with that of the bare SDC electrolyte, the performance of the single cell with the Fe-doped SDC is enhanced; for example, the peak power density is increased by 52.8% to 0.726 W cm-2 at 600 °C when humidified hydrogen is used as the fuel and ambient air is used as the oxidant. The single cell showed stable operation at 600 °C under a constant current density of 0.3 A cm-2 for 150 h. Therefore, the Fe-doped SDC solid solution shows promise as a potential electrolyte for low-to-intermediate-temperature SOFCs.

Perspective on high-temperature surface oxygen exchange in a porous mixed ionic-electronic conductor for solid oxide cells.

The surface exchange coefficient (k) of porous mixed ionic-electronic conductors (MIECs) determines the device-level electrochemical performance of solid oxide cells. However, a great difference is reported for k values, which are measured using presently available technologies of electrical conductivity relaxation (ECR), electrochemical impedance spectroscopy (EIS), and oxygen isotope exchange (OIE). In terms of this issue, this perspective paper estimates the possible physiochemical processes for the oxygen reduction reaction (ORR) in porous MIECs by comparing the oxygen supply/consumption fluxes through calculation. Then, the potential problems associated with ECR, EIS, and OIE for application in porous materials are discussed regarding theory, assumptions, sample requirements, and data processing. Finally, gas diffusion effects are revealed by comparing the simulated and measured ECR profiles, which show that the ORR process can be significantly delayed by gas diffusion. This perspective aims to recommend a reasonable method to characterize the true ORR kinetics of porous electrodes and quantify the effect of gas diffusion.

Cobalt-Free Double Perovskite Oxide as a Promising Cathode for Solid Oxide Fuel Cells.

Double perovskite oxide PrBaFe2O5+δ is a potential cathode material for intermediate-temperature solid oxide fuel cells. To improve its electrochemical performance, the trivalent element Ga is investigated to partially replace Fe, forming PrBaFe2-xGaxO5+δ (PBFGx, x = 0.05, 0.1, and 0.15). The doping effects on physicochemical properties and electrochemical properties are analyzed regarding the phase structures, element valence states, amount of oxygen vacancies, content of oxygen species, oxygen surface exchange coefficients (kchem), electrochemical polarization resistance, and single-cell performance. Specifically, PBFG0.1 exhibits improved kchem, such as a 19% improvement from 4.09 × 10-4 to 4.86 × 10-4 cm s-1 at 750 °C, due to the increased concentration of reactive oxygen species and oxygen vacancies. Consequently, the interfacial polarization resistance is decreased by 28% from 0.057 to 0.041 Ω cm2 at 800 °C. The subreaction steps of the oxygen reduction reaction in the PBFG0.1 cathode are further investigated, which suggests that the oxygen dissociation process is greatly enhanced by doping Ga. Meanwhile, doping Ga increases the peak power density of the anode-supported single cell by 36% from 629 to 856 mW cm-2 at 800 °C. The single cell with the PBFG0.1 cathode also exhibits good stability in 100 h of long-term operation at 750 °C.

Surface Self-Assembly Protonation Triggering Triple-Conductive Heterostructure with Highly Enhanced Oxygen Reduction for Protonic Ceramic Fuel Cells.

Triple-conducting (H+ /O2- /e- ) cathodes are a vital constituent of practical protonic ceramic fuel cells. However, seeking new candidates has remained a grand challenge on account of the limited material system. Though triple conduction can be achieved by mechanically mixing powders uniformly consisting of oxygen ion-electron and proton conductors, the catalytic activity and durability are still restricted. By leveraging this fact, a highly efficient strategy to construct a triple-conductive region through surface self-assembly protonation based on the robust double-perovskite PrBaCo1.92 Zr0.08 O5+δ , is proposed. In situ exsolution of BaZrO3 -based nanoparticles growing from the host oxide under oxidizing atmosphere by liberating Ba/Zr cations from A/B-sites readily forms proton transfer channels. The surface reconstructing heterostructures improve the structural stability, reduce the thermal expansion, and accelerate the oxygen reduction catalytic activity of such nanocomposite cathodes. This design route significantly boosts electrochemical performance with maximum peak power densities of 1453 and 992 mW cm-2 at 700 and 650 °C, respectively, 86% higher than the parent PrBaCo2 O5+δ cathode, accompanied by a much improved operational durability of 140 h at 600 °C.

Perovskite Oxyfluoride Ceramic with In Situ Exsolved Ni-Fe Nanoparticles for Direct CO2 Electrolysis in Solid Oxide Electrolysis Cells.

Solid oxide electrolysis cell (SOEC) is a potential technique to efficiently convert CO2 greenhouse gas into valuable fuels. Thus, there is significant interest in developing highly active and stable electrocatalysts for the CO2 reduction reaction (CO2RR). Herein, a Ni and F co-doping strategy is proposed to facilitate the exsolution reaction and form a new cathode, Ni-Fe alloy nanoparticles embedded in ceramic Sr2Fe1.5Mo0.5O6-δ (SFM) doped with fluorine. F-doping and Ni-Fe exsolution enhance CO2 adsorption by a factor of 2.4 and increase the surface reaction rate constant (kchem) for CO2RR from 6.79 × 10-5 to 18.1 × 10-5 cm s-1, as well as the oxygen chemical bulk diffusion coefficient (Dchem) from 9.42 × 10-6 to 19.1 × 10-6 cm2 s-1 at 800 °C. Meanwhile, the interfacial polarization resistance (Rp) decreases by 52%, from 0.64 to 0.31 Ω cm2. At 800 °C and 1.5 V, an extremely high current density of 2.66 A cm-2 and a stability test over 140 h are achieved for direct CO2 electrolysis in the SOEC.

Tuning the Phase Transition of SrFeO3-δ by Mn toward Enhanced Catalytic Activity and CO2 Resistance for the Oxygen Reduction Reaction.

Developing high-performance cathodes with sufficient stability against CO2 rooting in ambient atmosphere is crucial to realizing the practical application of solid-oxide fuel cells. Herein, the Mn dopant is investigated to regulate the phase structure and cathode performance of SrFeO3-δ perovskites through partially replacing the B-site Fe. Compared with parent SrFeO3-δ, Mn-doped materials, SrFe1-xMnxO3-δ (x = 0.05 and 0.1), show stabilized cubic perovskites at room temperature. Meanwhile, doping Mn accelerates the oxygen reduction reaction process, showing a reduced polarization resistance of 0.155 Ω·cm2 at 700 °C for SrFe0.95Mn0.05O3-δ, which is less than 30% of SrFeO3-δ. In addition, the Mn dopant improves the chemical oxygen surface exchange and bulk diffusion coefficients. Furthermore, Mn enhances the tolerance toward CO2 corrosion in various CO2 atmospheres. Density functional theory calculations also reveal that Mn can strengthen the structural stability and increase the activity for the oxygen reduction reaction.

Theoretical and Experimental Investigations on K-doped SrCo0.9 Nb0.1 O3-δ as a Promising Cathode for Proton-Conducting Solid Oxide Fuel Cells.

Improving proton conduction in cathodes is regarded as one of the most effective methods to accelerate the sluggish proton-involved oxygen reduction reaction (P-ORR) for proton-conducting solid oxide fuel cells (P-SOFCs). In this work, K+ dopant was used to improve the proton uptake and migration ability of SrCo0.9 Nb0.1 O3-δ (SCN). K+ -doped SCN (KSCN) demonstrated great potential to be a promising cathode for P-SOFCs. Density functional theory calculations suggested that doping with K+ led to more oxygen vacancies and more negative values of hydration enthalpy, which was helpful for the improvement of proton concentration. Importantly, the proton migration barriers could be depressed, benefiting proton conduction. Electrochemical investigations signified that the cell using KSCN cathode had a peak power density of 967 mW cm-2 at 700 °C, about 54.1 % higher than that using a SCN cathode. This research highlights the K+ -doping strategy to improve electrochemical performance of cathodes for P-SOFCs.

Infiltrated Ni0.08Co0.02CeO2-x@Ni0.8Co0.2 Catalysts for a Finger-Like Anode in Direct Methane-Fueled Solid Oxide Fuel Cells.

Direct utilization of methane in solid oxide fuel cells (SOFCs) is greatly impeded by the grievous carbon deposition and the much depressed catalytic activity. In this work, a promising anode, taking finger-like porous YSZ as the anode substrate and impregnated Ni0.08Co0.02Ce0.9O2-δ@Ni0.8Co0.2O as the novel catalyst, is fabricated via the phase conversion-combined tape-casting technique. This anode shows commendable mechanical strength and excellent catalytic activity and stability toward the methane conversion reactions, which is attributed to the exsolved alloy nanoparticles and the active oxygen species on the reduced Ni0.08Co0.02Ce0.9O2-δ catalyst as well as the facilitated methane transport rooting in the special open-pore microstructure of the anode substrate. Strikingly, this button cell delivers an excellent peak power density of 730 mW cm-2 at 800 °C in 97% CH4/3% H2O fuel, only 9% lower than that in 97% H2/3% H2O. Our work shed new light on the SOFC anode developments.

A Durable Ruddlesden-Popper Cathode for Protonic Ceramic Fuel Cells.

Protonic ceramic fuel cells (PCFCs) have been proved as an efficient energy converter at intermediate temperatures. To accelerate the kinetics of the proton-involved oxygen reduction reaction (p-ORR), developing efficient and durable cathodes is of great importance for improving PCFCs. In this work, a new triple-layered Ruddlesden-Popper (R-P) structure oxide, Sr3 EuFe2.5 Co0.5 O10-δ (3-SEFC0.5 ), was developed as a potential single-phase cathode for PCFCs, showing high oxygen non-stoichiometry and desirable structural thermal stability. By employing this highly active and stable single-phase cathode, the PCFC demonstrated unprecedented low polarization resistances and exceptionally great peak power densities, which were approximately 0.030â€…Ω cm2 and 900 mW cm-2 measured at 700 °C, respectively. These findings not only manifest the effectiveness of optimal doping in improving the structural stability and electrocatalytic activity in the multi-layered perovskite family, but also highlight the great potential of using multi-layered R-P series oxides as highly active and durable catalysts for PCFCs.

Hydrogen Oxidation Pathway Over Ni-Ceria Electrode: Combined Study of DFT and Experiment.

Ni-ceria cermets are potential anodes for intermediate-temperature solid oxide fuel cells, thanks to the catalytic activity and mixed conductivities of ceria-based materials associated with the variable valence states of cerium. However, the anodic reaction mechanism in the Ni-ceria systems needs to be further revealed. Via density functional theory with strong correlated correction method, this work gains insight into reaction pathways of hydrogen oxidation on a model system of Ni10-CeO2(111). The calculation shows that electrons tend to be transferred from Ni10 cluster to cerium surface, creating surface oxygen vacancies. Six pathways are proposed considering different adsorption sites, and the interface pathway proceeding with hydrogen spillover is found to be the prevailing process, which includes a high adsorption energy of -1.859 eV and an energy barrier of 0.885 eV. The density functional theory (DFT) calculation results are verified through experimental measurements including electrical conductivity relaxation and temperature programmed desorption. The contribution of interface reaction to the total hydrogen oxidation reaction reaches up to 98%, and the formation of Ni-ceria interface by infiltrating Ni to porous ceria improves the electrochemical activity by 72% at 800°C.

Vanadium-Doped Strontium Molybdate with Exsolved Ni Nanoparticles as Anode Material for Solid Oxide Fuel Cells.

Vanadium-doped strontium molybdate (SVM) has been investigated as a potential anode material for solid oxide fuel cells due to its high electronic conductivity of about 1000 S cm-1 at 800 °C in reducing atmospheres. In this work, NiO is introduced to SVM with the B-site excess design to induce in situ growth of Ni nanoparticles in the anodic operational conditions. The Ni particles are exsolved from the parent oxide phase as clearly demonstrated with various techniques including X-ray diffraction, X-ray photoelectron spectroscopy, scanning electron microscopy, and transmission electron microscopy. The exsolved Ni nanoparticles significantly boost the electrocatalytic activity toward fuel oxidation reaction, improving the peak power density by 160% from 0.21 to 0.56 W cm-2 at 800 °C when using H2 as the fuel, meanwhile reducing the total interfacial polarization resistance by 56% from 0.81 to 0.36 Ω cm2. The Ni-exsolved SVM anode also shows excellent catalytic activity toward H2S-containing and hydrocarbon fuels, providing peak power densities of 0.43, 0.36, and 0.22 W cm-2 at 800 °C for H2-50 ppm H2S, syngas, and ethanol, respectively. In addition, the cell with the Ni-exsolved SVM anode presents a stable power output, indicating that the Ni-SVM is a potential SOFC anode electrocatalyst for various fuels.

Oxygen-Deficient Ruddlesden-Popper-Type Lanthanum Strontium Cuprate Doped with Bismuth as a Cathode for Solid Oxide Fuel Cells.

Ruddlesden-Popper-type strontium-doped lanthanum cuprates are unique in oxygen defects because of the oxygen-deficient composition. This work increases the oxygen vacancy concentration through bismuth-doping and thus promotes the electrochemical performance for oxygen reduction reaction (ORR) in solid oxide fuel cells. X-ray diffraction shows that up to 10% A-site elements can be doped with bismuth. The doping improves the catalytic activity through (1) increasing oxygen vacancy concentration by 87.5 and 65.5% at room temperature and 800 °C, respectively, as demonstrated by iodometric titration and thermogravimetric analysis, (2) greatly reducing the energy for oxygen vacancy formation as shown by density functional theory calculation, (3) forming additional reactive oxygen species at the near surface region as suggested with X-ray photoelectron spectroscopy, and (4) enhancing the oxygen transport properties as exhibited with electrical conductivity relaxation. In addition, bismuth doping reduces the thermal expansion coefficient to a level that could exactly match the thermal expansion behavior to the electrolytes. Consequently, the interfacial polarization resistance for ORR is decreased by 43% at 800 °C for the cuprate-based composite electrodes. The decrease is greatly attributed to the enhancement in the charge-transfer process, the rate-limiting step. Further, the peak power density for a model cell is increased from 530 to 630 mW·cm-2 at 800 °C. Bismuth-doping is a promising strategy to modify the catalytic properties of unique cuprates toward ORR.

A Stable and Efficient Cathode for Fluorine-Containing Proton-Conducting Solid Oxide Fuel Cells.

Substitution of anions such as F- and Cl- can effectively improve the stability of proton-conducting electrolytes at no expense to proton conduction. However, during operation, F- and Cl- in electrolytes can transfer to the cathodes, which reduces the stability of the electrolytes. In this work, F- -doped Ba0.5 Sr0.5 Co0.8 Fe0.2 O3-δ [Ba0.5 Sr0.5 Co0.8 Fe0.2 O2.9-δ F0.1 (F-BSCF)] was prepared as a potential cathode for proton-conducting solid oxide fuel cells with BaCe0.8 Sm0.2 F0.1 O2.85 electrolyte. The incorporation of F- in the cathode depressed F- diffusion from the electrolyte and improved the stability of button cells. Temperature-changing X-ray photoelectron spectroscopy and electronic conductivity relaxation results demonstrated that the incorporation of F- enhanced the oxygen incorporation kinetics at intermediate temperatures and improved the cathode catalytic performance. Moreover, a button cell prepared with this novel cathode was stable for 270 h at a current density of 300 mA cm-2 and 700 °C, which was much superior than those containing a BSCF cathode.

New, Efficient, and Reliable Air Electrode Material for Proton-Conducting Reversible Solid Oxide Cells.

Driven by the demand to minimize fluctuation in common renewable energies, reversible solid oxide cells (RSOCs) have drawn increasing attention for they can operate either as fuel cells to produce electricity or as electrolysis cells to store electricity. Unfortunately, development of proton-conducting RSOCs (P-RSOCs) faces a major challenge of poor reliability because of the high content of steam involved in air electrode reactions, which could seriously decay the lifetime of air electrode materials. In this work, a very stable and efficient air electrode, SrEu2Fe1.8Co0.2O7-δ (SEFC) with layer structure, is designed and deployed in P-RSOCs. X-ray diffraction analysis and High-angle annular dark-filed scanning transmission electron microscopy images of SEFC reveal that Sr atoms occupy the center of perovskite slabs, whereas Eu atoms arrange orderly in the rock-salt layer. Such a special structure of SEFC largely depresses its Lewis basicity and therefore its reactivity with steam. Applying the SEFC air electrode, our button switches smoothly between both fuel cell and electrolysis cell (EC) modes with no obvious degradation over a 135 h long-term test under wet H2 (∼3% H2O) and 10% H2O-air atmospheres. A record of over 230 h is achieved in the long-term stability test in the EC mode, doubling the longest test that had been previously reported. Besides good stability, SEFC demonstrates great catalytic activity toward air electrode reactions when compared with traditional La0.6Sr0.4Co0.2Fe0.8O3-δ air electrodes. This research highlights the potential of stable and efficient P-RSOCs as an important part in a sustainable new energy power system.

Enhanced Oxygen Reduction Activity on Ruddlesden-Popper Phase Decorated La0.8Sr0.2FeO3-δ 3D Heterostructured Cathode for Solid Oxide Fuel Cells.

A new heterostructured (La,Sr)2FeO4-δ (LSF214)-La0.8Sr0.2FeO3-δ (LSF113) electrode has been synthesized to improve the oxygen reduction reaction (ORR). This new materials system was fabricated by the deposition of Sr(NO3)2 into the LSF113 framework followed by subsequent heat treatment, resulting in a new three-dimensional (3D) LSF214-LSF113 heterostructured electrode. This material system consists of a with Ruddlesden-Popper (R-P) LSF214 phase formed on the surface of the LSF113 framework. The ORR activity has been enhanced by 1 order of magnitude using the LSF214-LSF113 heterostructured electrode. The ORR enhancement was the result of higher catalytic activity of the LSF214 phase and a mismatch in the lattice parameter between LSF214 and LSF113 regions which results in oxygen molecule adsorption and oxygen vacancy formation become more favered. Impedance spectroscopy measurements revealed that the presence of LSF214 reduced the polarization resistance of the LSF113 electrode on a ceria-based electrolyte. The high frequency resistance (RH) and low frequency resistance (RL) decreased substantially due to the enhanced oxygen transport process and accelerated oxygen incorporation rate in the LSF214-LSF113 heterostructured electrode. The heterostructured LSF214-LSF113 electrode provides a promising new approach to improve the oxygen reduction reaction activity through multiphase materials systems with tailored microstructures.

Mechanism for the enhanced oxygen reduction reaction of La0.6Sr0.4Co0.2Fe0.8O3-δ by strontium carbonate.

Strontium doped lanthanum cobalt ferrite (LSCF) is a widely applied electrocatalyst for the oxygen reduction reaction (ORR) in solid-oxide fuel cells (SOFCs) operated at intermediate temperatures. Sr surface segregation in long-term operation has been reported to have contradicting effects that either degrade or improve the reaction. Thus, it is critical to understand the mechanism of surface Sr compounds on ORR kinetics. This work aims to verify the effect and propose the mechanism by decorating SrCO3 nanoparticles using the infiltration method. Electrochemical conductivity relaxation measurements show that SrCO3 particles improve the chemical oxygen surface exchange coefficient by up to a factor of 100. The electrochemical performance is significantly improved by the infiltration of SrCO3, which is comparable to those obtained by typical electrocatalysts including precious metals such as Pd and Rh. Distribution of relaxation time (DRT) analysis shows that the performance enhancement is strongly related to the improved kinetics of charge transfer and oxygen incorporation processes. Density functional theory calculations show that the surface SrCO3 reduces the O2 dissociation energy barrier from 1.01 eV to 0.33 eV, thus enhancing the ORR kinetics, possibly through changing the charge density distribution at the LSCF-SrCO3 interface.

High-Performanced Cathode with a Two-Layered R-P Structure for Intermediate Temperature Solid Oxide Fuel Cells.

Driven by the mounting concerns on global warming and energy crisis, intermediate temperature solid-oxide fuel cells (IT-SOFCs) have attracted special attention for their high fuel efficiency, low toxic gas emission, and great fuel flexibility. A key obstacle to the practical operation of IT-SOFCs is their sluggish oxygen reduction reaction (ORR) kinetics. In this work, we applied a new two-layered Ruddlesden-Popper (R-P) oxide, Sr3Fe2O7-δ (SFO), as the material for oxygen ion conducting IT-SOFCs. Density functional theory calculation suggested that SFO has extremely low oxygen ion formation energy and considerable energy barrier for O(2-) diffusion. Unfortunately, the stable SrO surface of SFO was demonstrated to be inert to O2 adsorption and dissociation reaction, and thus restricts its catalytic activity toward ORR. Based on this observation, Co partially substituted SFO (SFCO) was then synthesized and applied to improve its surface vacancy concentration to accelerate the oxygen adsorptive reduction reaction rate. Electrochemical performance results suggested that the cell using the SFCO single phase cathode has a peak power density of 685 mW cm(-2) at 650 °C, about 15% higher than those when using LSCF cathode. Operating at 200 mA cm(-2), the new cell using SFCO is quite stable within the 100-h' test.

Enhanced catalytic activity toward O2 reduction on Pt-modified La1-xSrxCo1-yFeyO3-δ cathode: a combination study of first-principles calculation and experiment.

Using the first-principles calculation and the electronic conductivity relaxation (ECR) experimental technique, we investigated the adsorption and dissociation behaviors of O2 on Pt-modified La0.625Sr0.375Co0.25Fe0.75O3-δ (LSCF) surface. Toward the O2 reduction, the calculation results show that the perfect LSCF (100) surface is catalytically less active than both the defective (100) surface and the perfect (110) surface. O2 molecule can weakly adsorb on the perfect LSCF (100) surface with a small adsorption energy of about -0.30 eV, but the dissociation energy barrier of the O2 molecule is about 1.33-1.43 eV. Doping of Pt cluster on the LSCF (100) surface can remarkably enhance its catalytic activity. The adsorption energies of O2 molecules become -1.16 and -1.89 eV for the interfacial Feint site and the Ptbri bridge site of Pt4-cluster, respectively. Meanwhile, the dissociation energy barriers are reduced to 0.37 and 0.53 eV, respectively. The migration energy barrier of the dissociated oxygen from the interfacial Pt to the LSCF surface is 0.66 eV, and it is 2.58 eV from the top site of the Pt cluster to the interfacial Pt site, suggesting that it is extremely difficult for oxygen to migrate over the Pt cluster. The Bader charge analysis results further indicate that the charges transferring from Pt cluster to LSCF surface promote the adsorption and dissociation of O2 molecules. Experimentally, a dramatic decrease of the surface oxygen exchange relaxation time was observed on Pt-modified LSCF cathode, with a chemical surface exchange coefficient increased from 6.05 × 10(-5) cm/s of the bare LSCF cathode to 4.04 × 10(-4) cm/s of the Pt-modified LSCF cathode, agreeing very well with our theoretical predictions.