Case Study on the Reproducibility of Characterizing the Electrocatalytic Activity of La_1−xSr_xMnO₃ in ORR

The electrocatalytic activity characterization of the oxygen reduction reaction (ORR) is commonly characterized using a rotating disk electrode (RDE) with linear sweep voltammetry (LSV) or cyclic voltammetry (CV) measurements. Despite the wide application of this method in the literature, its reproducibility and comparability are rarely mentioned in articles. LSV and CV are sensitive to experimental conditions, thus the reproducibility is a significant concern. In this article, the perovskite oxides La1−xSrxMnO3 (LSMOx, x = 0, 0.1, 0.2, 0.3, 0.4, 0.5) are chosen for the case study to measure their electroactivity using the RDE method. The main elements that influence the reproducibility of the experiment are presented and the corresponding explanations as well as the means for ensuring the reproducibility are given. Through the case study of LSMOx with variations in x and calcination temperatures, the values for the kinetic current of ORR on different catalysts are compared. It is found that doping ratios above 0.1 are associated with higher ORR electroactivity, with around a 50 mV difference in ORR onset potential between x > 0.1 and x = 0.1, which is in accordance with the results of reported works, whereas there is no significant difference when x = 0.2–0.5. Calcination temperature has little influence on the electroactivity of LSMOx, resulting in only a slight advantage at lower calcination temperatures, with an ORR onset potential that is around 10 mV more positive