Enhanced Visible Light Photocatalytic Activity of ZnO Nanowires Doped with Mn²⁺ and Co²⁺ Ions

In this research, ZnO nanowires doped with Mn²⁺ and Co²⁺ ions were synthesized through a facile and inexpensive hydrothermal approach, in which Mn²⁺ and Co²⁺ ions successfully substituted Zn²⁺ in the ZnO crystal lattice without changing the morphology and crystalline structure of ZnO. The atomic percentages of Mn and Co were 6.29% and 1.68%, respectively, in the doped ZnO nanowires. The photocatalytic results showed that Mn-doped and Co-doped ZnO nanowires both exhibited higher photocatalytic activities than undoped ZnO nanowires. Among the doped ZnO nanowires, Co-doped ZnO, which owns a twice active visible-light photocatalytic performance compared to pure ZnO, is considered a more efficient photocatalyst material. The enhancement of its photocatalytic performance originates from the doped metal ions, which enhance the light absorption ability and inhibit the recombination of photo-generated electron-hole pairs as well. The effect of the doped ion types on the morphology, crystal lattice and other properties of ZnO was also investigated.