Composites of Co-Doped Graphitic C₃N₄ Nanosheets and TiO₂ Nanoparticles for Electrorheological Fluid Applications

Herein, composites of Co-doped graphitic C3N4 nanosheets and TiO2 nanoparticles (Co-C3N4 NSs/TiO2 NPs) were prepared through a two-step synthetic strategy, and their electrorheological (ER) performance under varied electric field strengths was also researched. The microstructure, chemical elements, and surface morphology of materials were studied thoroughly by scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray powder diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy, Brunauer–Emmett–Teller (BET) test, and X-ray photoelectron spectroscopy (XPS) measurements. The presence of TiO2 NPs and g-C3N4 was confirmed by XRD and FTIR results. Typical SEM and TEM images revealed the apparent sheet-like nanostructure of Co-C3N4, and the filling of TiO2 NP in-layers was discovered. Meanwhile, BET results indicated the abundant pore structure of Co-C3N4 NSs/TiO2 NP composites. The ER performances of Co-C3N4 NSs/TiO2 NP composites, including shear stress, shear viscosity, and ER efficiency, were examined under different electric field strengths with a high-quality electrorheometer. Interestingly, the obtained Co-C3N4 NSs/TiO2 NP composites exhibited an excellent ER property including an unexpected ER efficiency (up to 196), superior platform area, obvious dielectric loss peak, and high shear stress (more than 600 Pa at 3.0 kV/mm), showing wide application prospects as electrorheological materials.