Synthesis, redox exfoliation, and magnetic nanoparticle decoration of VSe₂ and SnSe₂ nanosheets

Nanostructures exfoliated from layered van der Waals materials have attracted attention based upon their thickness-dependent optical and electronic properties. While magnetism has been observed in such 2D materials, available approaches to modulate or enhance their magnetic response remain limited. Thus, the magnetic response of 2D materials is of particular interest. Relatively few reports focus on colloidal routes to synthesize layered materials from which 2D nanostructures can be obtained by exfoliation. Herein, we present a general method to synthesize bulk vanadium diselenide (VSe₂) and dual-phase tin diselenide SnSe₂-SnSe followed by liquid phase redox exfoliation to delaminate these materials into 2D nanostructures of different thicknesses. The delamination process induces phase changes, affecting the overall magnetic and optical behavior. The magnetization of these 2D nanostructures of different thicknesses increases with an increasing exfoliation degree (decreasing size and thickness). Moreover, we decorated these 2D nanostructures with colloidally synthesized iron oxide dots (Fe _<i>x</i> O _<i>y</i> , ∼4 nm diameter). This enhanced the magnetic response, which reached a saturation magnetization of 32 emu g^-1 for VSe₂-Fe _<i>x</i> O _<i>y</i> and 2.7 emu g^-1 for SnSe₂-Fe _<i>x</i> O _<i>y</i> . A synergistic effect is observed, in which the magnetization of the Fe _<i>x</i> O _<i>y</i> decorated VSe₂ significantly exceeds that of either Fe _<i>x</i> O _<i>y</i> itself or VSe₂ alone. This report provides a general method to synthesize 2D nanostructures of varied thickness and to decorate them with magnetic nanoparticles to achieve synergistic magnetic response.