Factors influencing the measured surface reaction kinetics parameters

Abstract

Further understanding of the cathode oxygen reduction reaction mechanism is one of the most important challenges for the development of solid oxide fuel cells at low and intermediate temperature. Determining the surface reaction kinetics parameters such as the surface exchange coefficient and bulk diffusion coefficient is critical to reveal the cathode process. However, the reported results from different literatures are widely divergent and sometimes the variation can reach as high as over one order of magnitude even for the same cathode material. The various original data make it difficult to judge the reaction property and possibly weaken the reliability of the parameters. In this review paper, the recent progress of the oxygen reduction reaction kinetics parameters is comprehensively summarized for typical cathode material La 1Àx Sr x Co 1Ày Fe y O 3Àδ regarding the experimental methods and principles. Emphasis is also placed on the main influenced factors which may result in the reported variation. The main purpose of this paper is to provide a summary of recent progress and reveal the possible difference source for the surface reaction kinetics of oxygen reduction reaction.

Gas Humidification Impact on the Properties and Performance of Perovskite‐Type Functional Materials in Proton‐Conducting Solid Oxide Cells

“…The parameters of the first group lie in the materials science aspect and can be managed by the selection and optimization of electrode compositions; the parameters of the second group can be controlled through the optimization of technological methods. Analysis on the relationship between the electrochemical activity, kinetic and microstructural parameters has been thoroughly carried out . However, the influence of air humidification on the oxygen electrodes' performance was not clear, particularly for the proton‐conducting SOCs.…”

La-doped Ba0.5Sr0.5Co0.8Fe0.2O3- d as Cathode for Protonic-Conducting Solid Oxide Fuel Cells with Enhanced Structure Stability

“…As we previously reported, the oxygen chemical bulk diffusion coefficient, Dchem, and chemical oxygen surface exchange coefficient, kchem, of BSCF at 700  C are 2*10 -5 cm 2 S -1 and 4*10 -4 cm S -1 , respectively (12). Both the bulk diffusion coefficient and the surface exchange coefficient of BSCF are about one order of magnitude higher than those of classic electrocatalyst La0.6Sr0.4Co0.8Fe0.2O3- (LSCF) at the same temperature: 6.4*10 -6 cm 2 S -1 for kchem and 1.3*10 -5 cm S -1 for Dchem, respectively (13), and are comparable with those of PrBaCo2O5+ which is the state-of-the-art electrocatalyst for PCFCs cathodes (1*10 -5 cm -2 S -1 for Dchem and 1*10 -4 cm S -1 for kchem, respectively) (2,14). Therefore, BSCF is an excellent ORR electrocatalyst.…”

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

“…The transient change of conductivity with increase of oxygen partial pressure was recorded, and fitted to a solution of Fick’s second law to obtain the chemical surface exchange coefficient ( k Chem ) and the chemical oxygen bulk diffusion coefficient ( D Chem ). The experiment temperature was in the range from 650 to 800 °C, and more specific descriptions of ECR technique have been given before …”