Reduction of CO2 aqueous solution by using photosensitized-TiO2 nanotube catalysts modified by supramolecular metalloporphyrins-ruthenium(II) polypyridyl complexes

The photosensitized semiconductor catalysts – TiO2 nanotubes – were modified by functionalized supramolecular sensitizers: zinc(II)/copper(II)/cobalt(II) porphyrin-ruthenium(II) polypyridly complexes and photocatalytic activity of the modified TiO2 nanotubes were investigated through the reduction of CO2 aqueous solution as a probe reaction under UV–vis light. The diverse photoreduction properties of the catalysts resulted from the different polypyridly derivatives: 2,2′-bipyridyl, 1,10-phenanthroline, and 2,2′-bipyridyl-4,4′-dicarboxylate. The different central coordinated metal ions in the porphyrin ring influenced the photocatalytic efficiency of the sensitized-TiO2 system at the same time. A possible mechanism for the photocatalytic reduction was also proposed in this paper.

Graphical abstractThe photosensitized semiconductor catalysts – TiO2 nanotubes – were modified by functionalized supramolecular sensitizers: zinc(II)/copper(II)/cobalt(II) porphyrin-ruthenium(II) polypyridly complexes and photocatalytic activity of the modified TiO2 nanotubes were investigated through the reduction of CO2 aqueous solution as a probe reaction under UV–vis light. The diverse photoreduction properties of the catalysts were resulted from the different polypyridly derivatives: 2,2′-bipyridyl, 1,10-phenanthroline, and 2,2′-bipyridyl-4,4′-dicarboxylate. The different central coordinated metal ions in porphyrin ring influence the photocatalytic efficiency of the sensitized-TiO2 system at the same time. A possible mechanism of the photocatalytic reduction was also proposed in this paper.Figure optionsDownload full-size imageDownload high-quality image (269 K)Download as PowerPoint slideHighlights► Novel supramolecular photosensitizers TiO2 nanotube catalysts were synthesized. ► The TiO2 nanotube photocatalytic in CO2 reduction have not been report at present. ► All the photosensitizers enhanced the catalytic efficiency of bare TiO2 nanotube. ► The modified TiO2 catalysts displayed good methanol selectivity. ► A possible mechanism of the photocatalytic reduction was proposed in this paper.