Surface metal ion doped TiO2 nanowire arrays by low energy ion implantation for enhanced photoelectrochemical performance

Various metal ions, including Mg, Co, Nb, and W, were chfosen for ion implantation to modify TiO2 nanowire arrays. The introduction of metal ions was confirmed by both simulations and transmission electron microscopy (TEM) morphology characterization. A doped TiO2 shell on the surface was formed by the ion implantation process. Furthermore, the unbonded metal W was found in the doped TiO2 nanowires. The XPS results implied a special mechanism of heavy ions chosen for low-energy ion implantation. The presence of non-bonded metal restricted water splitting ability evidently. PEC results provided brief evidence that Nb doped TiO2 nanowire arrays is a promising choice with a 60% improvement in current density. The charge transfer resistance and the flat band potential are more benefit to water splitting than other doped metal ions. The theoretical calculation also supported efficient band gap narrowing of TiO2 caused by Nb dopant.