Electrocatalytic Activities of Perovskite toward Oxygen Reduction Reaction in Concentrated Alkaline Electrolytes

Abstract

Perovskite La 0.6 Ca 0.4 CoO 3 powder was prepared through a sol-gel method and characterized by XRD and BET. The electrocatalytic properties of La 0.6 Ca 0.4 CoO 3 (LCCO) and La 0.6 Ca 0.4 CoO 3 -Carbon composite (LCCO-C) based electrode layers towards oxygen reduction reaction (ORR) were studied using rotating ring-disk electrode technique (RRDE) in 1, 4, and 6 M KOH electrolytes. Koutechy-Levich theory and RRDE measurement were applied to acquire the overall electron transfer number and kinetic parameters, such as the kinetic currents and rate constants. The overall electron transfer number was measured to be almost 4 for both pure LCCO and composite LCCO-C. A synergetic effect toward the ORR was observed in the LCCO electrode layer in the presence of carbon. This synergetic effect might be one of the reasons for the improved ORR performance on the composite LCCO-C electrode.

Electrocatalytic Activity of Non-Stoichiometric Perovskites toward Oxygen Reduction Reaction in Alkaline Electrolytes

“…Compared to samples in the 1 M KOH electrolyte, the diffusion current in 6 M KOH is about 10 times smaller due to the decreased solubility and diffusion coefficient of oxygen, as well as the increased kinematic viscosity of the electrolyte at a higher KOH concentration, which agrees with our previous results [8]. According to Koutecky-Levich theory [10]: [1] where i dl is the diffusion-limiting current, n is the overall electron transfer number in ORR, F is the Faraday constant (96500 C mol -1 ), A is the geometric area of the disk electrode (0.16 cm 2 ), From Figures 8-10, the Koutecky-Levich (K-L) plots can be plotted for the La x Ca 0.4 MnO 3 /C electrodes in two KOH concentrations, as shown in Figure 11.…”

A review of cathode materials and structures for rechargeable lithium–air batteries

“…Perovskite and perovskite-related oxides have been widely used in solid-oxide fuel cell (SOFC), [454][455][456][457] superconductors 458,459 and semiconductorbased gas sensors. 460 These oxides generally have good catalytic activity towards both ORR and OER at high temperature 461 or in aqueous systems especially in alkaline conditions for low temperature metal-air batteries 108,[462][463][464][465][466][467][468][469] In recent years, perovskite oxides have also attracted much attention in nonaqueous Li-air batteries to facilitate the kinetics of ORR as well as OER. 108,312,[470][471][472][473][474][475] Fu et al 472 prepared nano-sized perovskite oxides of g-La 0.8 Sr 0.2 MnO 3 and s-La 0.8 Sr 0.2 MnO 3 with high purity by sol-gel and solid-state reaction method, respectively, and made a scrutiny into Li-air batteries as cathode catalysts.…”