A novel Cr₂O₃ coated CNTs system: Synthesis, microstructure regulation, and characterization

Surface modification is an attractive strategy for expanding, improving, or altering the properties and functions of carbon nanotubes (CNTs), which opens up a broad range of novel applications. Herein, a simple, and efficient approach for the synthesis of the Cr₂O₃ coated CNTs system was developed, and the morphologies and microstructures of the coating on CNTs along with annealing temperature were systematically investigated. It was found the continuous amorphous (Cr₂O₃)_1/2·(H₂O)_3/2 coating with a thickness of about 3–4 nm can be decorated onto CNTs with the applied coating processes, and which can be transformed into continuous amorphous Cr₂O₃ coating after annealing at 500 °C for 0.5 h. With further increasing the annealing temperature to 700 °C, nano Cr₂O₃ particles with high crystallinity were formed at the expense of amorphous Cr₂O₃ coating, and the coating on the surface of CNTs can be completely consumed for transforming into crystalline Cr₂O₃ nanoparticles when the annealing temperature is up to 800 °C. The findings provide important guidance for the surface modification of CNTs and lay the foundation for the industrial application of the novel Cr₂O₃ coated CNTs.