The orbital hybridization between metal and oxygen of perovskite catalysts can lower the overpotential and enhance the oxygen evolution reaction (OER) activity. This study combines density functional theory with experiments to clarify how Sr/Fe codoping modulates orbital hybridization and enhances OER catalytic activity of LaCoO3. The as-prepared La0.50Sr0.50Co0.75Fe0.25O3 shows remarkable performance with a low overpotential of 310 mV at 10 mA cm–2 current density and a 107.03 mV dec–1 Tafel slope, outperforming most state-of-the-art perovskite-based OER electrocatalysts. The experimental results confirm that Sr/Fe codoping enhances the expansion of Co–O–Co bond angles and strengthens the covalency of the Co–O bond in LaCoO3, leading to enhanced electrocatalytic activity. Moreover, increasing Sr doping reduces the distance between the Co 3d/O 2p center and the Fermi level, decreasing the energy difference between them and enhancing the degree of orbital hybridization between Co 3d and O 2p. As the degree of Co 3d/O 2p orbital hybridization increases, a higher charge transfer was found between the active center and intermediate product, OOH, reducing the energy barrier of the rate-determining step while lowering the overpotential. This study provides thorough insight into the rational design of OER catalysts based on orbital hybridization.
Wenjing Kong,Xueyun Zhong,Ying Yan,Yun Xing,Lei Liu,Chuan Yu,Leneng Yang,Xiaofei Song,Mingli Fu
With the widespread use of waterborne coatings, the treatment of volatile organic compounds (VOCs), which is also easy to produce odor pollution, has become the major concern of the air pollution control in coating industry. Since the deep oxidation of the butyl acetate (BA) molecule requires the involvement of a large amount of reactive oxygen species, the catalytic oxidation of BA was promoted by weakening the Co-O bond strength on the cobalt oxide surface. In this study, we adopted a simple sacrificial template approach to fabricate a series of specifically shaped and uniform Co3O4 catalysts for the catalytic oxidation of BA. The flake CM71-C catalyst showed the most excellent catalytic properties of BA (T50 = 197 °C, T90 = 215 °C). According to the characterization results, flake CM71-C has the largest specific surface area and the weakest Co-O bond, which is more conducive to redox and oxygen activation capabilities of catalyst. The results of In-situ DRIFTS studies showed that the surface reactive oxygen species were continuously recharged during the reaction due to the higher oxygen activation capacity, which accelerated the rapid decomposition of carboxylate, a key reactive intermediate species in the deep oxidation of BA. This study provides a practical and effective way to gain insight into the role of oxygen vacancies in the preparation of efficient catalysts with specific morphology for VOCs oxidation.
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