Bond formation and relaxation are effective methods to alter the electronic and photonic behavior of semiconductor. With the aid of first principle calculations, the electronic properties of TiO2 have been modulated by the impurity C, Fe, Co or H atom. Results show that, the electronic distribution around the impurity atoms is changed by the bonds formation and relaxation. The electronic and photonic behavior of TiO2 based photocatalysts are altered by modulating the number and energy of impurity level and reducing the band gap. Moreover, the carrier mobility in impurity levels increased after the H atom being introduced into, which not only reduce the electronic transition energies but also suppress the electron-hole recombination rate. Finally, the Co-C-2H codoped TiO2 may have the best photocatalytic activity. (C) 2015 Elsevier B.V. All rights reserved.