2.2. Electrode Fabrication
ZnO nanorods were synthesized by a two-step chemical bath
deposition (CBD) technique, then coated with TiO2 nanoparticles
by electrostatic layer-by-layer deposition, as previously reported
[28]. The ethanolic ZnO seed layer precursor solution was modified
by the addition of 0.6 M H2O to increase the spacing between the
nanorods [29]. Doping ZnO with Co2+ and TiO2 with Zr4+ was
achieved by substituting 10 mol% of the zinc nitrate with cobalt(II)
nitrate and 5 or 10 mol% of titanium tetraisopropoxide with
zirconium tetraisopropoxide, respectively.