Detailed Study of a TiO2-phenol Complex Using Deuterated Phenol

Interfacial charge-transfer transitions (ICTTs) between organic compounds and inorganic semiconductors have recently attracted much interest for their potential applications in photoenergy conversions and chemical sensing. A TiO2-phenol complex is one of the most fundamental ICTT systems. However, the adsorption structure and electronic and optical properties have not been scrutinized yet. Here, we examine the TiO2-phenol complex in detail using deuterated phenol. The experimental and computational vibrational analysis reveals that phenol is dissociatively adsorbed on TiO2 with deprotonation of the hydroxy group. The dissociative adsorption induces much stronger ICTT via d-pi electronic couplings than the non-dissociative adsorption.