Effective Promotion of Oxygen Reduction Reaction by in Situ Formation of Nanostructured Catalyst

Abstract

Efficient electrocatalysts for oxygen reduction reaction (ORR) are critical to high-performance energy conversion and storage devices. As an important family of functional materials, alkaline earth metal oxides are generally considered inert toward electrochemical reactions. Here we report the remarkable enhancement of ORR activity and durability of electrodes enabled by surface modification with a precursor of barium nitrate. During cell start-up process, an ORR active cobaltite catalyst was in situ formed on the electrode surface, as confirmed by scanning transmission electron microscopy (STEM) analysis. A combination of in situ/operando Raman and electrochemical impedance study suggests that the transition from nitrate to cobaltite may occur at ∼565 °C. The peak power density of a single cell at 750 °C is increased from ∼0.85 to ∼1.15 W cm–2 (35% increase) by the surface modification, demonstrating the remarkable enhancement of electrocatalytic activity under realistic operating conditions.

Enhancing Oxygen Reduction Activity and Cr Tolerance of Solid Oxide Fuel Cell Cathodes by a Multiphase Catalyst Coating

“…There is a possibility that some interaction between the LSCF backbone and the porous BaCO 3 coating may result in a newly formed mixed conducting phase, which enhanced the electrocatalyst activity of the LSCF cathode. [ 27,55 ] Figure 3b and Table S1, Supporting Information, compare the R p values of our MP catalyst‐coated LSCF cathode with other catalyst‐coated LSCF cathodes reported to date. As observed, the MP catalyst‐coated LSCF shows the lowest R p at 600–750 °C.…”

“…[20][21][22][23] Surface modification with catalyst coatings has been demonstrated as an effective strategy to enhance the ORR activity and contaminant tolerance of cathodes. [24][25][26][27][28][29] The catalyst coatings can increase the number of ORR active sites and protect LSCF from reacting with contaminates. [20,[30][31][32][33] Several types of catalysts have been developed, including precious metals (e.g., Pd, Ag, and Ru), oxygen ion-conducting oxides (Sm 0.2 Ce 0.8 O 2−δ [SDC], [34] and Gd 0.2 Ce 0.8 O 1.9 (GDC)), [33,35] mixed ionic and electronic conductors (e.g., LSCF, [36] Sm 0.5 Sr 0.5 CoO 3−δ (SSC), [36] and PrSrCoMnO 6−δ , [25] etc.…”

Promotion of oxygen reduction and evolution by applying a nanoengineered hybrid catalyst on cobalt free electrodes for solid oxide cells

“…The here prepared hybrid-catalyst-coated LSF electrode is among the fastest ones reported on cobalt-free materials. 18,36 Even though it is LSF based and cobalt-free, its performance matches those of the high-performance cobalt-containing electrodes reported recently, including LSCF or LSCF nanofiber 9 , BSCF-CGO10 mixture or nanofibers 12 , SrTi0.3Fe0.63Co0.07O3−δ (STFC-07) 37 and PBCC 14 as well as several representative surface-coated-electrodes such as PrSrCoMnO6-δ (PSCM)coated LSCF 38 , multi-phase catalysts (composed of BaCoO3−x (BCO) and PrCoO3−x (PCO) nanoparticles and a conformal PBCC thin film)-coated LSCF 39 , SSC-coated LSCF/CGO10 40 , PrNi0.5Mn0.5O3 (PNM) thin film and PrOx nanoparticles-coated LSCF 21 , and cobaltite-coated PBCC 41 (Fig. 2c).…”

“…Encouragingly, the behavior of the hybridcatalyst-coated LSF cell reported here competes well with those of high-performance SOCs based on cobalt-containing electrodes. 14,21,38,41,44 Fig. 4d shows typical EIS data of the hybrid-catalyst-coated LSF cell and the LSF cell acquired at 750 °C under OCV conditions.…”

Stabilizing Fe–N–C Catalysts as Model for Oxygen Reduction Reaction

“…into carbon frameworks to form TM–H–C structures can further boost the ORR performance of non‐noble‐metal catalysts. [ 8 ] it is worth noting that such catalysts are readily suffered fast decay, especially in the actual working environment, which greatly restrains the commercial application of TM–H–C catalysts. [ 9 ] Finally, multiple efforts have been devoted to synchronously achieving the TM–H–C catalyst with superior activity and durability/stability.…”