Effect of A‑Site Defects on the Catalytic Activity of Perovskite LaCoO₃: Insights from the Electronic Structure

The development of highly active perovskite-based catalysts for the oxidation of volatile organic chemicals (VOCs) has drawn a great deal of attention. A-site defect regulation is found to be effective to improve the catalytic performance, but the relationship between structure variation and catalytic activity has not been clearly unveiled. Herein, this issue was interpreted by the variation of physicochemical properties and electronic structure (O p-band center). An in situ one-step calcination method with NH₄HCO₃ addition was adopted to prepare a series of A-site-deficient LaCoO₃ perovskites (L_xCO), which were characterized by XRD, TEM, EELS, ESR, XPS, UPS, H₂-TPR, and O₂-TPD and catalytic test toward toluene oxidation. The catalytic activity displayed a volcano-type relationship with an addition amount of NH₄HCO₃. The electronic structure determined the reducibility and active oxygen content and accordingly affected the catalytic activity of L_xCO. The obtained results provide theoretical and technical support for the design of efficient VOC oxidation catalysts.