Galvanic molecular intercalation

Abstract: The intercalation of molecular species between the layers of van der Waals (vdW) materials has recently emerged as a powerful approach to combine the remarkable electronic and magnetic properties of vdW materials with the chemical flexibility of organic molecules. However, the full transformative potential of molecular intercalation remains underexplored, largely due to the lack of simple, broadly applicable methods that preserve high crystalline quality down to the few-layer limit. Here, we introduce a simple galvanic approach to intercalate different molecules into various vdW materials under ambient conditions, leveraging the low reduction potential of selected metals to enable a spontaneous molecular insertion. We employ our method, which is particularly well-suited for the in-situ intercalation of few-layer-thick crystals, to intercalate nine vdW materials, including magnets and superconductors, with molecules ranging from conventional alkylammonium ions to metallorganic and bio-inspired chiral cations. Notably, intercalation leads to a molecule-dependent enhancement of the superconducting transition in 2H-TaS2, reaching a critical temperature of 4.7 K, higher than TaS2 monolayers. Additionally, RuCl3 exhibits an unprecedented transition from antiferromagnetic to ferrimagnetic ordering upon intercalation with cobaltocenium. These results establish our approach as a versatile technique for engineering atomically thin quantum materials and heterostructures, unlocking the transformative effects of molecular intercalation.