Synthesis of an aqueous, air-stable, superconducting 1T'-WS 2 monolayer ink.

Liquid-phase chemical exfoliation can achieve industry-scale production of two-dimensional (2D) materials for a wide range of applications. However, many 2D materials with potential applications in quantum technologies often fail to leave the laboratory setting because of their air sensitivity and depreciation of physical performance after chemical processing. We report a simple chemical exfoliation method to create a stable, aqueous, surfactant-free, superconducting ink containing phase-pure 1T'-WS 2 monolayers that are isostructural to the air-sensitive topological insulator 1T'-WTe 2 . The printed film is metallic at room temperature and superconducting below 7.3 kelvin, shows strong anisotropic unconventional superconducting behavior with an in-plane and out-of-plane upper critical magnetic field of 30.1 and 5.3 tesla, and is stable at ambient conditions for at least 30 days. Our results show that chemical processing can make nontrivial 2D materials that were formerly only studied in laboratories commercially accessible.