Formation of dimer radical cation of 1,1-dianisylethylene through two-step hole transfer processes during TiO2 photocatalytic reactions

The formation of the 1,1-dianisylethylene dimer radical cation ((DAE)2+) during TiO2 photocatalytic reactions was successfully investigated by the transient absorption measurement with time-resolved diffuse reflectance spectroscopy. This reaction was explained in terms of the cascade hole transfer processes from the photo-generated holes in the TiO2 particles to free DAE (DAEfree) in the bulk solution mediated by the radical cation of p-phenylbenzoic acid adsorbed on the TiO2 surface (PBAads+).