Nowadays, two-dimensional transition metal chalcogenides have become attractive materials for flexible wearable devices because of their intriguing chemistry characteristics and sensitivity to external stimuli. However, the growth of two-dimensional materials on polymer surfaces is generally carried out by the time-consuming and costly chemical vapor deposition method. Reducing the manufacturing and integration costs while improving the device performance remains to be challenging. Herein, we report a simple liquid metal-assisted hydrothermal method for the growth of two-dimensional nanomaterials on the polymer surface. Specifically, a layer of liquid metal was coated on commercial tape, while layered cobalt sulfide was grown on its surface by a simple one-step hydrothermal method. Different kinds of flexible sensors can be prepared, such as bending sensor, pressure sensor, and humidity sensor, which can be used to detect motion, writing, breathing, and other signals. This strategy can also be assigned to sensing signals on different objects, which may further expand and enrich the application of two-dimensional materials in sensing.

We have demonstrated a facile and efficient strategy for the fabrication of soluble reduced graphene oxide sheets (RGO) and the preparation of titanium oxide (TiO₂) nanoparticle–RGO composites using a modified one-step hydrothermal method. It was found that graphene oxide could be easily reduced under solvothermal conditions with ascorbic acid as reductant, with concomitant growth of TiO₂ particles on the RGO surface. The TiO₂–RGO composite has been thoroughly characterized by Fourier transform infrared spectroscopy, Raman spectroscopy, X-ray diffraction, X-ray photoelectron spectroscopy, and thermogravimetric analysis. Microscopy techniques (scanning electron microscopy, atomic force microscopy, and transmission electron microscopy) have been employed to probe the morphological characteristics as well as to investigate the exfoliation of RGO sheets. The TiO₂–RGO composite exhibited excellent photocatalysis of hydrogen evolution.

An in situ chemical synthesis approach has been employed to prepare an Ag-chemically converted graphene (CCG) nanocomposite. The reduction of graphene oxide sheets was accompanied by generation of Ag nanoparticles. The structure and composition of the nanocomposites were confirmed by means of transmission electron microscopy (TEM), atomic force microscopy (AFM) and X-ray diffraction. TEM and AFM results suggest a homogeneous distribution of Ag nanoparticles (5–10 nm in size) on CCG sheets. The intensities of the Raman signals of CCG in such nanocomposites are greatly increased by the attached silver nanoparticles, i.e., there is surface-enhanced Raman scattering activity. In addition, it was found that the antibacterial activity of free Ag nanoparticles is retained in the nanocomposites, which suggests they can be used as graphene-based biomaterials.