  We synthesized the pure and co-doped titanium dioxide (TiO$_2$) electrodes
via spin coating. We examined the optical and electronic properties of
as-prepared thin film electrodes with co-doping of transition metals and
non-metals. The co-doping of Cu, Zn, and N increase the absorption of the
radiation in the visible region. The doping leads to the formation of defect
states in the electrodes. In this article, we have studied the carrier kinetics
in pristine and co-doped TiO2 electrodes. To study the role of dopants in
carrier transport of the synthesized TiO2 based electrodes, the electrochemical
impedance spectroscopy measurement is performed in the frequency range of 10-1
Hz to 106 Hz. The study reveals the influence of dopants on electron-hole
recombination in the defect sites present in bulk and the transport mechanism
of the electrons and ions to the surface/interface of the electrodes.
