Promoting sodium storage performance of bacteria-derived carbon/MoS₂-MoSe₂ heterostructure enabled by carbon dot

Two-dimensional metal sulfides/selenides with high theoretical capacity and unique layered structure have been extensively studied as anode materials for sodium-ion batteries (SIBs). However, they generally suffer from low conductivity and large volume expansion during charging-discharging process, which in turn significantly limiting the sodium storage performance. In this work, a MoS₂-MoSe₂ heterostructure has been epitaxially grown onto the Escherichia coli (EC)-derived carbon scaffold via a facile hydrothermal reaction regulated by carbon dot and post-selenization process. By virtue of the superior conductive network and excellent structural stability enabled by the dual carbon incorporation, the newly-designed CD-MoSe₂-MoS₂/EC electrode demonstrates a high reversible specific capacity of 450.5 mAh g^-1 at a current density of 100 mA g^-1 and outstanding rate capability, maintaining 284 mAh g^-1 at a high current density of 2000 mA g^-1, used as an anode for SIBs. Moreover, ex/in situ characterizations and first-principle calculation results unveil that the constructed MoS₂/MoSe₂ heterostructure effectively increases active sites and enhances the ion adsorption capacity, while the expanded interlayer spacing of MoS₂ further accelerates ion diffusion. This work provides a feasible design strategy for developing sustainable, low-cost, and high-performance electrode materials for next-generation sodium-ion storage.