Effect of the substrate morphology on the adsorption of Ru‐bipyridyl sensitizers on anatase TiO₂

Abstract The effects of the morphology of anatase TiO 2 substrates on the adsorption nature of Ru‐bipyridyl complexes with carboxylate groups as anchoring moieties have been investigated with infrared absorption spectroscopy and electron microscopy. The investigated dyes were the recently synthesized [Ru(dcbpyH 2 ) 2 (bpy‐TPA 2 )](PF 6 ) 2 , Ru‐TPA 2 , and the well‐known (Bu 4 N) 2 [Ru(dcbpyH) 2 (NCS) 2 ], N719, complexes. As substrates, TiO 2 paste films and pristine anatase nanopowder were used. Scanning electron microscopy images show big differences in the grain size, shape, and dispersity of the titania nanoparticles. The attenuated total reflection Fourier transform infrared spectra suggest that the coordination of both complexes on the TiO 2 paste films occurs via bidentate or bridging linkage. The adsorption of the dyes on pristine anatase nanopowder appears to be via bridging or bidentate chelate linkage for the dye N719 as well, however, the Ru‐TPA 2 complex appears to bind via unidentate or ester‐like linkage or by direct physisorpion via H‐bonding.