Efficient coupling of semiconductors into metallic MnO2@CoMn2O4 heterostructured electrode with boosted charge transfer for high-performance supercapacitors

Semiconductor heterostructures have emerged as highly promising candidates for energy storage and conversion owing to their tunable electronic and structural properties by rational design and controllable synthesis at a molecular level. The overall electrochemical performance of the semiconductor heterostructures often depends on the carrier mobility from the semiconductor interfaces and faradaic redox reactions from their active sites. Herein, we report a facile, low-cost, two-step method to controllably grow MnO2 nanorods directly on CoMn2O4 nanosheets (i.e., MnO2@CoMn2O4) with robust adhesion. An induced electric field resulted from the interface effect of heterostructures tailors the kinetic performance of electrons and ions during the charge-discharge process, enhancing the electron mobility and reducing diffusion barrier for charge carriers (OH-) ions migration. As a result, the rational design and controllable heterostructures exhibit significantly improved electrochemical capacitive performance, including remarkable specific capacitance, excellent rate capability, and cycling stability. Furthermore, exploring MnO2@CoMn2O4 as positive electrode and N-doping 3D reduction of graphene oxide (N-3DrGO) as negative electrode yields an asymmetric supercapacitor with high energy density (230.57 mWh cm(-2)), remarkable power density (3.91 mW cm(-2) at 149.99 mWh cm(-2)), and excellent cycling stability (81.3% capacitance retention after 5000 cycles at 3 mA cm(-2)). This work offers new opportunities to explore high-performance electrode materials by providing methods to control the interface in nano-heterostructures. (C) 2020 Elsevier Ltd. All rights reserved.