Selective Solid-Liquid Interface Sulfidation Growth of Hierarchical Copper Sulfide and Its Hybrid Nanoflakes for Superior Lithium-Ion Storage.

Two-dimensional metal sulfides and their hybrids are emerging as promising candidates in various areas. Yet, it remains challenging to synthesize high-quality 2D metal sulfides and their hybrids, especially iso-component hybrids, in a simple and controllable way. In this work, a low-temperature selective solid-liquid sulfidation growth method has been developed for the synthesis of CuS nanoflakes and their hybrids. CuS nanoflakes of about 20 nm thickness and co-component hybrids CuO /CuS with variable composition ratios derived from different sulfidation time are obtained after the residual sulfur removal. Besides, benefiting from the mild low-temperature sulfidation conditions, selective sulfidation is realized between Cu and Fe to yield iso-component FeO /CuS 2D nanoflakes of about 10-20 nm thickness, whose composition ratio is readily tunable by controlling the precursor. The as-synthesized FeO /CuS nanoflakes demonstrate superior lithium storage performance (i. e., 707 mAh g at 500 mA g and 627 mAh g at 1000 mA g after 450 cycles) when tested as anode materials in LIBs owing to the advantages of the ultrathin 2D nanostructure as well as the lithiation volumetric strain self-reconstruction effect of the co-existing two phases during charging/discharging processes.