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.
Kabir Fazal,Murtaza Adil,Saeed Azhar,Ghani Awais,Ali Anwar,Khan Saleh,Kaili Li,Qizhong Zhao,Kang Yao Kang,Yang Sen
Room temperature ferromagnetism with the doping of magnetic ions in the semiconducting host is the fundamental criterion for the potential use of spintronics material. In the present study, pure and (Fe, Tb) co-doped ZnO nanoparticles were well-prepared via the co-precipitation method, and corresponding microstructural, magnetic, and optical properties were investigated. The formation of Wurtzite hexagonal crystal structure of pure and doped ZnO was confirmed by X-ray diffraction (XRD) studies. No secondary phase was detected in all samples. Microstructural analysis reveals the spherical morphology of synthesized particles with the average size in the nanometer range. Fourier transforms infrared spectra show Tb–Zn–O stretching at 550 cm −1 . Optical absorption spectra show that the bandgap decreases and the absorption band slightly shift toward the visible region with increasing Tb doping, which may be due to the transfer of charge between the Tb ion 4f level and ZnO valance band. The photoluminescence (PL) spectrum exhibits a strong emission in the visible range, and PL emission intensity decreases with increasing Tb concentration and is anticipated to be due to the low recombination rate of electron–hole pairs. Most importantly, the room temperature ferromagnetism (RTFM) was observed in the doped ZnO nanoparticles, ascribed to the bound magnetic polaron (BMP) mechanism. The optical and magnetic outcome demonstrates that prepared (Fe, Tb) co-doped ZnO based dilute magnetic semiconducting (DMS) material are potential candidates for spintronics applications.
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