An activity descriptor for perovskite oxides in catalysis

Perovskite oxides are a class of important metal oxide catalysts, the activities of which are explained largely by the delocalized band descriptor and the local orbital descriptor that are fundamentally debated. We solve this dispute by proposing a frontier band orbital descriptor that rationalizes catalytic activity trends over a series of perovskite oxides. The descriptor is defined as the energy difference (Δ ε ) between the highest occupied band orbital and the lowest unoccupied band orbital, as determined by using valence-band X-ray photoelectron spectroscopy and O K -edge X-ray absorption spectroscopy, respectively. Catalytic activity in CO or NO oxidation increases linearly as Δ ε value decreases, evidencing the validity of the descriptor. Owing to the frontier orbitals of catalytic sites being endowed with characteristics of delocalized bands of entire catalysts, this descriptor gives unified explanations to disparate reported results, providing a promising strategy for designing optimal semiconducting metal oxide catalysts, particularly for perovskite catalysts. • The frontier band orbital is proposed as an effective activity descriptor • This descriptor (Δ ε ) is based on both band theory and frontier orbital theory • Catalytic activity in CO or NO oxidation increases linearly as Δ ε value decreases • A new perspective is provided to elaborate the electronic effect of oxides in catalysis Heterogeneous catalysts play a key role in industrial applications and environmental remediation. Thus, an effective activity descriptor is extremely significant for the rational design of high-performance heterogeneous catalysts. Here, we propose a new frontier band orbital as an effective activity descriptor for metal oxides, which is expressed as an energy difference (Δ ε ) between the lowest unoccupied band orbital and the highest occupied band orbital of the metal oxides. Furthermore, the frontier band orbital descriptor can provide a satisfactory unified explanation for disparate literature results and predict catalyst activity, demonstrating that it may be a more useful activity descriptor for other metal oxide catalysts. We propose the frontier band orbital as a new effective activity descriptor for metal oxides, which is expressed as an energy difference (Δ ε ) between the lowest unoccupied band orbital and the highest occupied band orbital of the metal oxides. This descriptor could not only provide a fundamental understanding of activity trends of metal oxides, especially for catalytic oxidation with the rates modulated by the electron-transfer surface reactions, but also serve as an effective design principle for developing improved or new catalysts.