Electrochimica Acta, Vol.296, 945-953, 2019
Polymer-assisted approach to LaCo1-xNixO3 network nanostructures as bifunctional oxygen electrocatalysts
Energy depletion caused by the consumption of fossil fuels due to increasing population and economic growth has stimulated intense research on electrochemical energy storage systems, including fuel cells and metal-air batteries. Oxygen electrocatalysis, including both oxygen reduction reaction (ORR) and oxygen evolution reaction (OER), dominates the performance of these electrochemical energy systems. However, the sluggish kinetics of these two reactions still limits their performance and even the commercialization of these electrochemical energy storage systems. Therefore, development of nonprecious metal-based oxygen catalysts, especially with bifunctionality for both OER and ORR, is greatly demanded. In this report, polymer-assisted approach has been employed to synthesize LaCoO3-based perovskite nanoparticles, which interconnected together to form porous network structures. X-ray diffraction indicated that replacement of Co with Ni would lead to a lattice expansion due to larger ionic radius of Ni3+ as compared to that of Co3+. The electrocatalytic activity of these materials in 0.1 M KOH aqueous solution showed that ORR performance of LaCoO3 can be improved through incorporation of Ni into the B-site while their OER performance will also be enhanced which renders these perovskite oxides to exhibit better bifunctional electrocatalytic activity for both OER and ORR. The enhanced performance with Ni-doping might be due to the synergistic effect from the two transition metals as a result of the formation of new redox couples Ni3+/Ni2+ as well as the higher Co3+/Co2+ ratio, which could promote adsorption of oxygen on the catalytic surface with improved the Co-O bond strength. Our study not only introduces polymer-assisted method to prepare network structured perovskite nanoparticles, but also highlights the importance of B-site metal doping in perovskites as a simple strategy to enhance their bifunctional oxygen catalytic activities. (C) 2018 Elsevier Ltd. All rights reserved.