In-situ High-Resolution Transmission Electron Microscopy and X-ray Diffraction Studies on Nanostructured β-SiC and Its Promising Feature for Photocatalytic Hydrogen Production

Abstract

The ruin of energy and environmental pollution has led to the pursuit of novel technologies for green energy productions. For hydrogen energy itself, the search for the photocatalytic-based nanostructured β-SiC is one of the main research focus during the last few years. Herein, we reported the successful magnesiothermic reduction at low temperature, i.e., 700 °C, using an argon gas tubular furnace to fabricate β-SiC with a particle size below 10 nm. The X-ray diffraction (XRD) data collection and Rietveld refinement showed the single phase of moissanite β-SiC formation having cubic structure with lattice constants of a = b = c = 4.3523(50) Å and α = β = γ = 90°. The formation of the nanostructured β-SiC was well confirmed by the high-resolution transmission microscopy (HRTEM) image. The equivalent crystallite size produced by the XRD profile analysis was 4.2(8) nm, and extracted from the HRTEM image was about 6 nm. The d-spacing for (111) plane met a reliable agreement between the XRD and HR-TEM data. The energy dispersive X-ray spectroscopy in scanning transmission electron microscopy (STEM-EDS) also brought a good capture for the nearly 50:50 concentration of Si:C in our sample. Furthermore, in-situ heating experiments via HR-TEM were also conducted. In brief, carbon nanolayers were initiated on the surface of the nanostructured β-SiC. All these fine-tuned crystallographic properties assigned the as synthesized β-SiC to be the promising candidate for photocatalytic hydrogen production.