Smart tuning of 3D ordered electrocatalysts for enhanced oxygen reduction reaction

Extensive research has been devoted to the development of advanced oxygen reduction reaction (ORR) catalysts with functionally diverse active sites. Herein, we show a smart approach to advancing the ORR catalytic activity of a 3D porous perovskite. The facile oxidative-reductive-oxidative (O-R-O) thermal treatment cycle executed on Ag doped LaFeO3 could stepwise switch on three different reaction sites (exsolved Ag-NPs, oxygen deficiency and Fe4+ with optimal electron configuration) for ORR. Detailed characterizations illustrate that the ORR activity is basically derived from the hierarchically porous scaffold which provides a large surface area and enough pore volumes for mass and ion diffusion. More importantly, the unique synergistic effects among three separate kinds of reaction sites endow the speed-up of oxygen adsorption, activation and O2- transportation. The exemplified results set out new design principles for the optimization of alternative catalysts. (C) 2017 Elsevier B.V. All rights reserved.