V ions implanted ZnO nanorod arrays for photoelectrochemical water splitting under visible light

In this work, V ions were doped into ZnO nanorod arrays via an advanced ion implantation method for photoelectrochemical water splitting under visible light. It was indicated that the V dopants were incorporated into ZnO lattice as V⁴⁺ and V⁵⁺ ions. V ion doping expanded the optical absorption of ZnO nanorod arrays into visible light region and led to considerable photoelectrochemical performance under visible light illumination (λ > 420 nm). The photocurrent density of V ions doped ZnO nanorod arrays could achieve 10.5 μA/cm² at 0.8 V (vs. Ag/AgCl), which was about 4 times higher than that of the pure ZnO nanorod arrays. The enhancement in photoelectrochemical performances for V ions doped ZnO nanorod arrays should be attributed to the improved visible light absorption ability and the increased charge carrier density induced by V ion doping.