Lattice Oxygen Engineering on Perovskite Oxide Catalysts: Concurrent Enhancement of Reactivity and Replenishment for Volatile Organic Compounds Oxidation

Abstract

The catalytic volatile organic compound oxidation poses a dilemma for perovskite (ABO₃) catalysts, as their high lattice oxygen reactivity (electron-deficient O^–(2–x)) depends on attracting coordinated oxygen electrons through an increased electronegativity of B-site cations, but this impedes the healing of oxygen vacancies and thus results in a low concentration of active lattice oxygen due to the limited O₂ dissociation in electron-deficient environments. Herein, we compress [Co/MnO₆] octahedra through A-site Cs⁺ doping in the double perovskite (La₂CoMnO_6−σ), which optimizes the orbital hybridization between Co/Mn 3d and O 2p. This promotes electron transfer from O to Co/Mn while reducing Co/Mn electronegativity, resulting in a synergistic improvement of lattice oxygen reactivity and oxygen vacancy healing. As a result, La_1.70Cs_0.30CoMnO_6−δ exhibits a remarkable 30.2-fold and 4.5-fold increase in toluene oxidation rates at 200 °C compared to LaMnO₃ and La₂CoMnO_6−σ, respectively, surpassing the reported Co/Mn-based perovskites. Due to its ultrahigh lattice oxygen reactivity and abundant active lattice oxygen, benzaldehyde intermediates predominantly governed by adsorbed oxygen are synchronously oxidized to CO₂ and H₂O by lattice oxygen, enabling Mars-van Krevelen reactions to function efficiently coupled with Langmuir–Hinshelwood reactions. This work harmonizes the reactivity and abundance of lattice oxygen, offering a robust strategy to advance the development of high-performance perovskite catalysts for catalytic oxidation.