PHOTOCATALYTIC REDUCTION OF CO2 USING SURFACE-MODIFIED CDS PHOTOCATALYSTS IN ORGANIC-SOLVENTS

The photocatalytic reduction of carbon dioxide on CdS particles with a nd without surface modification by several kinds of thiol compounds wa s investigated in various kinds of solvents. Formate and carbon monoxi de were obtained as the major reduction products, and the ratio of the former to the latter was largely influenced by the kind of solvents w hen naked cadmium sulfide was used as the photocatalyst, and with incr ease of the dielectric constant of the solvent, the ratio increased. E ven if CdS particles were modified by thiol compounds, the effect of t he solvent was not eventually altered, but the ratio of formate to car bon monoxide became greater with increase of the surface modification of CdS. The observed effect of the surface modification of CdS is disc ussed in terms of involvement of Cd2+ sites adjacent to surface vacanc ies of CdS photocatalysts in adsorption of anion radicals of CO2. (C) 1998 Elsevier Science S.A.