Influence of Current Density on the Photocatalytic Activity of Nd:TiO₂ Coatings

The Nd:TiO2 PEO coatings were formed in a phosphate-based electrolyte with the addition of Nd2O3 under the current density of 150, 200, 250 and 300 mA/cm(2). SEM results showed that the micropores decreased on quantity and increased on scale with the increasing current density. AFM results revealed that the roughness of the coatings increased with the increasing current density. Phase and composition analysis showed that the Nd:TiO2 coatings were mainly composed of anatase and rutile phase. And the anatase phase content has reached the maximum value at the current density of 250 mA/cm(2). XPS results indicated that Ti2p spin-orbit components of the Nd:TiO2 coatings are shifted towards higher binding energy, compared with the pure TiO2 coating, suggesting that some of the Nd3+ ions are combined with TiO2 lattice and led to dislocation. Photocatalytic test showed that the photocatalytic activity of Nd:TiO2 coatings varied in the same pattern with the anatase content variation in Nd:TiO2 coatings. The photocatalytic experiment results show that the photocatalytic activity of Nd:TiO2 coatings can be greatly enhanced with moderate amount of Nd3+. However, excessive amount of Nd3+ does not have an effective impact on the photoctalytic activity improvement.