The development of an effective cocatalyst for the modification of TiO 2 arrays has become highly desirable for the improvement of their photoelectrocatalytic properties. We investigated the modification of TiO 2 with nickel-based cocatalysts (nickel (Ni 0 ), nickel oxide (NiO), and nickel sulphide (NiS)) by electrochemical deposition. The formation of n-p heterojunctions for the Ti/TiO 2 /NiO and Ti/TiO 2 /NiS and the generation of Schottky-type barrier for the Ti/TiO 2 /Ni 0 led to the enhancement of visible light absorption and the reduction of the band gap energy, contributing significantly to improving the electrogeneration of the electron−hole and lifetime of the holes. The Ti/TiO 2 /NiS photocurrent was found to be almost two times higher than that of the Ti/TiO 2 (5.39 mA.cm −2 at +1.50 V); this result was attributed to the excellent distribution of the cocatalyst around the TiO 2 nanotube walls, which helped enhance the chemical interaction on the TiO 2 /NiS interface. Under optimized conditions (+0.50 V and UV-vis irradiation), the application of the Ti/TiO 2 /NiS electrode for the photoelectrocatalytic treatment of penicillin-G-(PG) (10 mg l −1 ) resulted in complete removal and mineralization after 60 min at pH 7. The results showed that one can potentially increase the photoelectrocatalytic efficiency of Ti/TiO 2 through a simple modification of the material.

The effect of phosphorene as co-catalyst in Ti/TiO2 nanotubes electrodes on CO2 reduction to methanol, and water splitting was investigated. The electrode was prepared by using poly-dopamine as anchoring agent...