Self-driven approach for local ion intercalation in vdW crystals
Intercalation has proven to be a powerful strategy for physical and chemical properties modulation in two dimensional (2D) van der Waal (vdW) materials. Traditional gaseous and chemical intercalation methods offers the ability for mass production, and the electrochemical method provides the reversible fine tuning for in-situ material investigation. Spatial control, or even direct patterning, of the ions, is widely required for practical device fabrication and integration, yet it is not realized. Here we demonstrate a self-driven ion (Co2+, Sn4+, Cu2+) intercalation approach with patterning ability on vdW α-MoO3. It’s proved that the self-driven intercalation was enabled by the formation of a local galvanic cell, and could be controlled by the metal electrode potential and the solution concentration. The universality of self-intercalation was confirmed in various types of 2D materials (MoS2, WS2, MoSe2, WSe2 and graphene). Furthermore, the feasibility of building heterostructure by multiple species (Sn & Co) intercalation in a single nanosheet was demonstrated for broadband photodetection. Enhancement of conductivity and photoresponse was found due to the synergistic effect of lattices distortion from Sn intercalation and d orbital from Co atom. This approach offers a feasible way for direct nano-fabrication in 2D vdW material and functional device integration.