Density functional theory study of α-cyanoacrylic acid adsorbed on rutile TiO2(110) surface

The investigation of adsorption properties of anchor group on photo-anode is foundation in the optimization of dye sensitizers (DS) for solar cells. alpha-cyanoacrylic acid (CAA) is the typical anchor moiety coupled electronic acceptor in DS. To understand the interaction between rutile TiO2 photo-anode and DS based upon CAA in dye sensitized solar cells, the atomic configurations, energies and electronic properties of CAA adsorbed on rutile TiO2(1 1 0) surface were studied by using density functional theory calculations. The results indicate CAA prefers to dissociatively adsorb on rutile TiO2(1 1 0) surface as bidentate configuration in which the O atoms of CAA bind with two adjacent surface five-coordinate Ti atoms along [001] direction, and the H atom in hydroxyl of CAA adhere to the nearest neighbor surface O atom at bridge site, generating a hydroxyl species. The corresponding adsorption energy is 1.480 eV. The analysis of geometrical parameters, density of states and electron density suggests the bonds between rutile TiO2(1 1 0) surface and CAA are formed. The density of states and orbital character at the gamma-point in reciprocal space support that the adsorption of CAA on the surface provides feasible mode for photo-induced electron injection. (C) 2016 Elsevier B.V. All rights reserved.