In situ Raman study of the photoinduced behavior of dye molecules on TiO(2)(hkl) single crystal surfaces

In dye-sensitized solar cells (DSSCs), the TiO(2)/dye interface significantly affects photovoltaic performance. However, the adsorption and photoinduced behavior of dye molecules on the TiO(2) substrate remains unclear. Herein, shell-isolated nanoparticle-enhanced Raman spectroscopy (SHINERS) was used to study the adsorption and photoinduced behavior of dye (N719) molecules on different TiO(2)(hkl) surfaces. On TiO(2)(001) and TiO(2)(110) surfaces, the in situ SHINERS and mass spectrometry results indicate S[double bond, length as m-dash]C bond cleavage in the anchoring groups of adsorbed N719, whereas negligible bond cleavage occurs on the TiO(2)(111) surface. Furthermore, DFT calculations show the stability of the S[double bond, length as m-dash]C anchoring group on three TiO(2)(hkl) surfaces in the order TiO(2)(001) < TiO(2)(110) < TiO(2)(111), which correlated well with the observed photocatalytic activities. This work reveals the photoactivity of different TiO(2)(hkl) surface structures and can help with the rational design of DSSCs. Thus, this strategy can be applied to real-time probing of photoinduced processes on semiconductor single crystal surfaces.