Manual shaking exfoliation of large-size two-dimensional LiInP₂S₆ nanosheets with exponential change in ionic conductivity for water detection

Large-sized and atomically thin two-dimensional metal thiophosphate materials have been widely exploited in detectors due to their rich physical/chemical properties of high surface area and massive adjustable sites. However, existing production methods are limited in terms of meeting the demanding challenges in achieving the scalable fabrication of high-quality nanomaterials under mild conditions. Here, we develop a facile intercalation-exfoliation method that can fabricate large lateral size (>23 mu m) and few-layer LiInP2S6 nanosheets with high crystalline quality fast. Due to the advantage of hydrophilicity of lithium, swelled interlayer spacing can be obtained, which enables the rapid exfoliation by only slight manual shaking within tens of seconds. Concomitantly, the inorganic LiInP2S6 film manufactured by nanosheets has inter-connected ionic channels, which can be adjusted on the basis of the water content, enabling tunable ionic conductivity. As a result, ionic conductor films using ions as charge carriers can achieve high water response with good repeatability and excellent long-term stability in a wide moisture range. Moreover, the as-prepared detector has excellent capability in real-time noncontact human-machine interfacing. This study, not only is a powerful strategy for the fabrication of large-sized and high-quality nanosheets presented but also proof for the promising development of iontronic devices in new applications.