C-60 Adsorbed on TiO2 Drives Dark Generation of Hydroxyl Radicals

Abstract

The photocatalytic effect of TiO2 has attracted a great deal of interest due to its many applications, especially water splitting. However, the wide band gap of TiO2 limits its efficiency as a photocatalyst in practical applications. Considerable efforts have so far been made to extend the spectral response to the visible light region. Here, we report the dark catalysis of water dissociation on a TiO2 (110) surface. C-60 molecules "decorated" this surface and acted as molecular electron acceptors. This adsorption of C-60 molecules on TiO2 led to an increase in the surface hole concentration due to charge transfer, eventually resulting in the dissociation of water molecules in the absence of photons. Hydroxyl radical was formed as a dissociation product, indicating that water dissociation occurred only via oxidation of H2O by the holes. The method presented here is simple and can be widely applied for tuning and enhancing the catalytic activity of various photocatalytic systems.