Methods to form atomically thin carbon coatings on SnS and SnO₂ nanostructures

We report a citric acid-assisted solvothermal method to construct C@SnS@C sandwich nanosheets, which assemble into 3D porous microspheres. Citric acid plays a key role in both controlling the growth of the thin (5 nm) SnS nanosheets by absorption on the (100) SnS surface, and in the formation of an amorphous atomically thin carbon (ATC) layer (0.8 nm) on the surface of SnS nanocrystals through carbonization. The C@SnS@C sandwich nanosheets are used as precursors to form porous microsphere SnO₂@ATC composites, with the SnO₂ nanoparticles (10–20 nm) grown on the extended carbon framework. We demonstrate how the synergetic effect of the high theoretical lithium storage capacity of SnO₂ and electrical conductivity of the atomically thin carbon framework renders this composite a promising anode material for lithium ion batteries with enhanced capacity and superior cycling performance.