Activation of Surface Oxygen Sites in a Cobalt-Based Perovskite Model Catalyst for CO Oxidation.

Anionic redox chemistry is becoming increasingly important in explaining the intristic catalytic behavior in transition-metal oxides and improving catalytic activity. However, it is a great challenge to activate lattice oxygen in noble-metal-free perovskites for obtaining active peroxide species. Here, we take La0.4Sr0.6CoO3-δ as a model catalyst and develop an anionic redox activity regulation method to activate lattice oxygen by tuning charge transfer between Co4+ and O2-. Advanced XAS and XPS demonstrate that our method can effectively decrease electron density of surface oxygen sites (O2-) to form more reactive oxygen species (O2- x), which reduces the activation energy barriers of molecular O2 and leads to a very high CO catalytic activity. The revealing of the activation mechanism for surface oxygen sites in perovskites in this work opens up a new avenue to design efficient solid catalysts. Furthermore, we also establish a correlation between anionic redox chemistry and CO catalytic activity.