Preparation of boron carbide nanosheets with high neutron-shielding properties based on reduced graphene oxide aerogel

Abstract

For this paper, boron carbide nanosheets were synthesized using a simple solid-phase thermal reaction with reduced graphene oxide (rGO) aerogel as a carbon source and amorphous boron powder as a boron source. The phase, structure, morphology, and particle size of the prepared B4C were characterized by X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM), Fourier transform infrared spectroscopy (FT-IR), Raman spectroscopy, transmission electron microscopy (TEM), X-ray photoelectron spectra (XPS) and nanoparticle size distribution analysis. The effect of the reaction temperature, reaction time and B/C molar ratio on the crystal structure of B4C were also investigated. The results showed that the optimum conditions for the synthesis of B4C nanosheets were a reaction temperature of 1450 °C, a reaction time of 4 h and a B/C molar ratio of 4. The resulting nanosheets are hexagonal in shape, with edge lengths of 200–500 nm and an average thickness of about 100 nm. The crystal structure of the nanosheet is rhombohedral. The formation mechanism of the nanosheets is discussed on the basis of the experimental results. In addition, testing the neutron-shielding properties of the B4C composites showed that neutron transmittance with a B4C nanosheets content of 25 wt% was 94.83% lower (from 56.47% to 2.92%) than with epoxy resin, and the total macroscopic absorption cross-section was 518.41% greater (from 0.2857 ± 0.0023 cm−1 to 1.7668 ± 0.0004 cm−1). Hence, the results of this study identify a lightweight, effective material with excellent neutron-shielding properties.