MoS₂/MnO₂ heterostructured nanodevices for electrochemical energy storage

Hybrid or composite heterostructured electrode materials have been widely studied for their potential application in electrochemical energy storage. Whereas their physical or chemical properties could be affected significantly by modulating the heterogeneous interface, the underlying mechanisms are not yet fully understood. In this work, we fabricated an electrochemical energy storage device with a MoS₂ nanosheet/MnO₂ nanowire heterostructure and designed two charge/discharge channels to study the effect of the heterogeneous interface on the energy storage performances. Electrochemical measurements show that a capacity improvement of over 50% is achieved when the metal current collector was in contact with the MnO₂ instead of the MoS₂ side. We propose that this enhancement is due to the unidirectional conductivity of the MoS₂/MnO₂ heterogeneous interface, resulting from the unimpeded electrical transport in the MnO₂-MoS₂ channel along with the blocking effect on the electron transport in the MoS₂-MnO₂ channel, which leads to reaction kinetics optimization. The present study thus provides important insights that will improve our understanding of heterostructured electrode materials for electrochemical energy storage.