Elevating the Orbital Energy Level of <i>d</i>_xy in MnO₆ via <i>d–π</i> Conjugation Enables Exceptional Sodium‐Storage Performance

Abstract

Abstract Transition metal oxides (TMOs) suffer from inherently low electronic conductivity, while atom orbital related regulation can be critical to promote the electron transfer kinetics in energy storage applications. Herein, the study utilizes a d–π conjugation strategy to improve the electronic conductivity of TMOs. Briefly, phthalocyanine (Pc) molecules with large conjugated systems are selected to modify transition metal oxide ( δ ‐MnO 2 ). By density functional theory (DFT) simulations, it is clarified that the strong d–π conjugation between MnO 2 and Pc can elevate the orbital energy level of low energy orbital ( d xy ) in MnO 6 units, which further activates the redox activity of d xy . The delocalized π electrons from Pc to MnO 6 unit repel the original d xy electrons, and then elevate the d xy orbital energy level, thus facilitating the electron transfer in MnO 2 ‐Pc. Subsequently, the MnO 2 ‐Pc exhibits a significant specific capacitance of 310 F g −1 at 1 A g −1 . At a power density of 900 W kg −1 , the fabricated asymmetric supercapacitor delivers a maximal energy density of 50.3 Wh kg −1 . This work paves the way to boost the redox activity of transition metal center in TMOs by regulating the orbital energy level, which can be expanded to design other advanced energy materials.