Photocatalytic reduction of CO₂ with SiC recovered from silicon sludge wastes

Abstract

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.

Keywords:

• photocatalytic reduction of CO₂
• recovery of SiC
• formic acids

Acknowledgements

The financial supports by the Taiwan National Science Council, Bureau of Energy, and Ministry of Economic Affairs (Project #: 101-EC-17-A-10-S1-187) are gratefully acknowledged.