Photocatalytic reduction of CO2with SiC recovered from silicon sludge wastes

In the present study, silicon carbide (SiC) recovered from silicon sludge wastes is used as catalysts for photocatalytic reduction of CO2. By X-ray diffraction, it is clear that the main components in the silicon sludge wastes are silicon and SiC. The grain size of the SiC separated from the sludge waste is in the range of 10–20 µm in diameter (observed by scanning electron microscopy). By solid state nuclear magnetic resonance, it is found that α-SiC is the main crystallite in the purified SiC. The α-SiC has the band-gap of 3.0 eV. To yield C1–C2 chemicals from photocatalytic reduction of CO2, hydrogen is provided by simultaneous photocatalytic splitting of H2O. Under the light (253–2000 nm) illumination, 12.03 and 1.22 µmol/h g cat of formic and acetic acids, respectively, can be yielded.