Photoelectrochemical water oxidation over TiO 2 nanotubes modified with MoS 2 and g-C 3 N 4 .

TiO 2 nanotube arrays (TNAs) have been studied for photoelectrochemical (PEC) water splitting. However, there are two major barriers of TNAs, including a low photo-response and the fast charge carrier recombination in TNAs, leading to poor photocatalytic efficiency. Through a comparison of MoS 2 /TNAs and g-C 3 N 4 /TNAs, it was found that TNAs modified with MoS 2 and g-C 3 N 4 exhibited a current density of, respectively, 210.6 and 139.6 μA·cm -2 at an overpotential of 1.23 V vs RHE, which is 18.2 and 12 times higher than that of pure TNAs under the same conditions. The stability of the MoS 2 /TNAs heterojunction is higher than that of g-C 3 N 4 /TNAs.