Modification of TiO2 semiconductor with molecules bearing functional phosphonic groups: a 31P solid state NMR study

In order to advance the work on the characterization of titanium oxide hetero-assemblies formed by surface modification with functional molecular materials, we are engaged in a solid state NMR study of the molecules chemisorption on the surface of the semiconductor. We present here the preliminary results of our study on two model organic compounds, methyl phosphonic acid and phenyl phosphonic acid, which are assembled to TiO2 via the phosphonic acid moiety. We are focusing on the 31P magnetic behavior, considering the obtained data as a very interesting tool that may lead to the elucidation of the adsorbent/semiconductor interaction and the optimization of the corresponding dye-sensitized solar cells. The above results are further supported by FT-IR experiments on titania powder sensitized by a RuII dye bearing functional phosphonic acid groups.