A dual heterostructure enables the stabilization of 1T-rich MoSe2 for enhanced storage of sodium ions

Abstract

Electron injection effectively induces the formation of a 1T-rich phase to address the low conductivity of MoSe₂. Nevertheless, overcoming the inherent metastability of the 1T phase (particularly during the conversion reactions that entail the decomposition–reconstruction of MoSe₂ and volume expansion) remains a challenge. Guided by DFT results, we designed a composite with bimetal selenides-based heterostructures anchored on reduced graphene oxide (rGO) nanosheets (G-Cu₂Se@MoSe₂) to obtain stabilized 1T-rich MoSe₂ and enhanced ion transfer. The construction of 1T-rich MoSe₂ and built-in electric fields (BiEF) through electron transfer at the heterointerfaces were realized. Moreover, the rGO-metal selenides heterostructures with in situ-formed interfacial bonds could facilitate the reconstruction of the 1T-rich MoSe₂-involved heterostructure and interfacial BiEF. Such a dual heterostructure endowed G-Cu₂Se@MoSe₂ with an excellent rate capability with a capacity of 288 mA h g⁻¹ at 50 A g⁻¹ and superior cycling stability with a capacity retention ratio of 89.6% (291 mA h g⁻¹) after 15 000 cycles at 10 A g⁻¹. Insights into the functional mechanism and structural evolution of the 1T MoSe₂-involved dual heterostructure from this work may provide guidelines for the development of MoSe₂ and phase-engineering strategies for other polymorphistic materials.