Mesoporous SiC with Potential Catalytic Application by Electrochemical Dissolution of Polycrystalline 3C-SiC

Abstract

Electrochemical dissolution of highly doped (ρ ∼ 1 mΩ·cm, n-type) polycrystalline 3C-SiC in HF/H2O and HF/H2O/ethanol solutions allowed production of porous silicon carbide (por-SiC) and soluble carbon fluorooxide nanoparticles as a byproduct. The por-SiC is a crystalline material with large pore volume, surface area close to 100 m2 g–1, and open mesoporous structure. The surface of por-SiC is covered with a thin carbon-enriched layer, bearing carboxylic acid groups. Depending on the SiC resistivity, etchant composition, and current density, three different types of por-SiC morphology, namely, a macroporous tubular, mesoporous hierarchical, and mesoporous filamentary were revealed. A qualitative physical model of SiC electrochemical dissolution, based on the phenomena of quantum confinement, charge carriers trapping onto the surface defects, and the surface passivation, was proposed, and the model successfully interpreted the dependencies of por-SiC morphology and material balance on the etching conditions. The por-SiC is anticipated to be a prospective material for catalytic, nanofiltration, and sensing applications.