Dual‐Defects Adjusted Crystal‐Field Splitting of LaCo1−xNixO3−δ Hollow Multishelled Structures for Efficient Oxygen Evolution

To boost the performance for various applications, a rational bottom‐up design on materials is necessary. The defect engineering on nanoparticle at the atomic level can efficiently tune the electronic behavior, which offers great opportunities in enhancing the catalytic performance. In this paper, we optimized the surface oxygen vacancy concentration and created the lattice distortion in rare‐earth‐based perovskite oxide through gradient replacement of the B site with valence alternated element. The dual defects make the electron spin state transit from low spin state to high spin state, thus decreasing the charge transport resistance. Furthermore, assembly the modified nanoparticle subunits into the micro‐sized hollow multishelled structures can provide porous shells, abundant interior space and effective contact, which enables an enhanced mass transfer and a shorter charge transport path. As a result, the systemic design in the electronic and nano‐micro structures for catalyst has brought an excellent oxygen evolution performance. Vacant and distorted: The microstructure of hollow multishelled structure (HoMS) perovskite oxides combined with the dual‐defects of surface oxygen vacancies and lattice distortion tuned the crystal‐field splitting energy, which promotes the thermodynamic and kinetic processes for the oxygen evolution reaction (OER).