Semiconductor Photocatalysis. Part 22. Visible-Light Induced Photoreduction of CO2 with CdS Nanocrystallites — Importance of the Morphology and Surface Structures Controlled through Solvation by N,N-Dimethylformamide

Carbon dioxide (CO2) is reduced to CO on hexagonal CdS nanocrystallites (mean diameter of 4 nm) prepared in N,N-dimethylformamide (DMF) under visible-light irradiation with a quantum yield of 0.098 at λ = 405 nm in the presence of TEA as an electron donor. Solvation of the surface of CdS nanocrystallites by DMF or a related amide molecules should control the crystalline growth and stabilize the favorable morphology with a size quantization-effect. The effect of Cd2+ or H2S on CO production and the emission behavior, and the effect of electron donors suggest an important role of the surface structures of CdS–DMF for photo-induced electron transfer to CO2. The scope and limitation of the photoreduction of CO2 with semiconductor nanoparticles are discussed.