Nanoporous silver-modified LaCoO3-δ perovskite for oxygen reduction reaction. (20th September 2021) - Liang, Yi
Highlights: Annealing promotes to form more Co 3+ and oxygen vacancies on the LaCoO3-δ surface. Triple-phase boundaries act as the active sites for electrocatalysis. The nanoporous Ag-LaCoO3-δ catalyst shows improved ORR performance. Abstract: Substantial progress has been made in developing perovskite-based catalysts for oxygen reduction reaction (ORR). This article reported an ORR electrocatalyst composed of nanoporous Ag (NP-Ag) and LaCoO3-δ (LC) perovskite oxide and designed to take advantage of the bi-continuous NP structure and high electrocatalytic performance of perovskite oxides. The triple-phase boundaries (TPBs) formed by NP-Ag and LC provided active sites for the electrocatalytic reactions. Further annealing promoted the interaction between NP-Ag and LC, which induced the formation of more Co 3+ and surface oxygen vacancies, as proved by multiple characterizations. When the mass ratio of LC and NP-Ag was 1:2 (LC/Ag-1/2-A), the catalyst showed the best ORR performance with a relatively high half-wave potential, and only attenuated by 4% after 5, 000 cycles of accelerated durability testing. Besides, it delivered significant bifunctionality towards both ORR and OER, bearing comparison with the reported perovskite-based electrocatalysts. This work demonstrated a novel route for extending the application of NP metals and facilely designing efficient bifunctional electrocatalysts. Graphical abstract: By mixing and annealing with nanoporous Ag, the charge transfer and surface chemical conditions of LaCoO3-δ perovskite is modified to boost the ORR performance. Image, graphical abstract