Five typical additives N-Butylbenzimidazole (NBB), N-Methylbenzimidazole (NMBI), 3-Methoxypropionitrile (MPN), 4-tert-butylpyridine (TBP) and Guanidinium thiocyanate (GNCS) are selected to investigate the diverse interactions with TiO2 anatase (101), (100) and (001) surfaces in vacuum and acetonitrile conditions, respectively, by means of the analyses of adsorption mode and electronic structure based on a periodic density functional theory method. Five additives are adsorbed more strongly in the order (101) < (100) < (001). The defects that appear in the upmost TiO2 (001) surface induced by additive adsorption affect bonding greatly. GNCS possesses the maximum adsorption energy due to special multidentate and dissociative adsorption modes, while MPN has the minimum adsorption energy, no matter which surface is used. Positive Fermi energy shift (i.e. negative potential shift) is in the order (100) < (001) < (101) for every additive adsorption. The larger shift results in the higher open-circuit photovoltage of dye-sensitized solar cells. Acetonitrile addition reduces the adsorption energy but improves the shift trend of Fermi energy except TBP-TiO2 (100) and (001) systems. There should be a critical point of adsorption density for MPN and TBP adsorption on the TiO2 (100) and (001) surfaces, changing Fermi energy shift from negative to positive value. (C) 2013 Elsevier B.V. All rights reserved.