Electro-Microfluidic Exfoliation of Air-Sensitive HfTe 2 into High-Quality Nanosheets and Electrically Continuous Thin Films

High Resolution Image Download MS PowerPoint Slide The scalable production of two-dimensional (2D) materials under inert, surfactant-free conditions remains a major challenge─particularly for air-sensitive compounds such as the topological semimetal HfTe 2 . Here, we present a microfluidic exfoliation strategy that integrates mechanical shear with localized electrochemical delamination to produce high-quality HfTe 2 nanosheets without stabilizing agents. Conducted entirely under an inert atmosphere, the process minimizes oxidation and preserves the intrinsic Dirac semimetal character of the material. The resulting dispersions enable the formation of dense, conformal thin films with clean internanosheet interfaces. Structural and spectroscopic analyses confirm that the microfluidically exfoliated nanosheets retain their crystallinity and stoichiometry, outperforming their conventionally electrochemically exfoliated counterparts. Electrical transport measurements reveal metallic conduction, indicating sufficient interflake coupling to maintain charge continuity across the film. However, the limited phase-coherence length derived from weak antilocalization and the presence of disorder-induced Parish–Littlewood-type magnetoresistance indicate that long-range quantum coherence is not preserved. These results demonstrate that microfluidic exfoliation yields electronically continuous yet structurally tunable films of air-sensitive layered semimetals, providing a scalable, surfactant-free pathway toward solution-processed, topological materials for low-power spintronic and quantum devices.