Unlocking supercapacitive energy storage potential: Catalyzing electrochemically inactive manganese oxides to active MnO2 via heterostructure reconstruction.

Advancing supercapacitor system performance hinges on the innovation of novel electrode materials seamlessly integrated within distinct architectures. Herein, we introduce a direct approach for crafting nanorod arrays featuring crystalline/amorphous CuO/MnO_2−x. This reconfigured heterostructure results in an elevated content of electrochemically active MnO₂. The nanorod arrays serve as efficient capacitive anodes and are easily prepared via low-potential electrochemical activation. The resulting structure spontaneously forms a p–n heterojunction, developing a built-in electric field that dramatically facilitates the charge transport process. The intrinsic electric field, in conjunction with the crystalline/amorphous architecture, enables a large capacitance of 1.0 F·cm⁻² at 1.0 mA·cm⁻², an ultrahigh rate capability of approximately 85.4% at 15 mA·cm⁻², and stable cycling performance with 92.4% retention after 10,000 cycles. Theoretical calculations reveal that the presence of heterojunctions allows for the optimization of the electronic structure of this composite, leading to improved conductivity and optimized OH⁻ adsorption energy. This work provides new insights into the rational design of heterogeneous nanostructures, which hold great potential in energy storage applications. [ABSTRACT FROM AUTHOR]