TiO₂@PEI-Grafted-MWCNTs Hybrids Nanocomposites Catalysts for CO₂ Photoreduction.

Anatase (TiO₂) and multiwalled carbon nanotubes bearing polyethylenimine (PEI) anchored on their surface were hybridized in different proportions according to a sol-gel method. The resulting nanocomposites (TiO₂@PEI-MWCNTs), characterized by BET, XRD, XPS, SEM, and UV techniques, were found efficient catalysts for CO₂ photoreduction into formic and acetic acids in water suspension and under visible light irradiation. PEI-grafted nanotubes co-catalysts are believed to act as CO₂ activators by forming a carbamate intermediate allowing to accomplish the first example in the literature of polyamines/nanotubes/TiO₂ mediated CO₂ photoreduction to carboxylic acids.