Hydrothermal-hot press processed SiO₂-rGO hybrid with enhanced physical properties

In this study, monoliths of SiO₂-rGO hybrids were obtained with improved physical properties by calcination-hot press processing. It was found that the oxygen-containing groups on graphene oxide were beneficial for the adsorption of ethyl silicate (C₈H₂₀O₄Si), leading to the uniform dispersion of rGO with SiO₂, which was obtained by hydrolysis of ethyl silicate during the hydrothermal reaction. The hybrid, which was subsequently calcinated for 1 h showed electrical conductivity of 0.143 S m⁻¹ together with higher thermal conductivity (1.612 Wm⁻¹k⁻¹), dielectric constant (10⁷), BET surface area (712.01 m²g⁻¹), and higher tensile strength (225.74 MPa). In addition, the enhanced value of electrical conductivity (0.02 S m⁻¹), thermal conductivity (1.439 Wm⁻¹k⁻¹), dielectric constant (500), tensile strength (98 MPa), and BET surface area (611.21 m²g⁻¹) were obtained for the silica-rGO (1.55 wt% rGO) as compared to the bare SiO₂. XRD characterization showed that an increase in calcination temperature and further hot-press processing at 750 °C led to enhanced crystallinity in the SiO₂ spheres in the hybrid, resulting in enhanced physical properties in the hybrids.