A dual heterostructure enables the stabilization of 1T-rich MoSe 2 for enhanced storage of sodium ions.

Electron injection effectively induces the formation of a 1T-rich phase to address the low conductivity of MoSe 2 . Nevertheless, overcoming the inherent metastability of the 1T phase (particularly during the conversion reactions that entail the decomposition-reconstruction of MoSe 2 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-Cu 2 Se@MoSe 2 ) to obtain stabilized 1T-rich MoSe 2 and enhanced ion transfer. The construction of 1T-rich MoSe 2 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 MoSe 2 -involved heterostructure and interfacial BiEF. Such a dual heterostructure endowed G-Cu 2 Se@MoSe 2 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 MoSe 2 -involved dual heterostructure from this work may provide guidelines for the development of MoSe 2 and phase-engineering strategies for other polymorphistic materials.