Eu-doped ZnO coatings prepared by spray pyrolysis for photocatalytic applications

The ZnO-Eu2O3 2 O 3 coatings immobilized on stainless steel foil were synthesized by a spray pyrolysis method using an inorganic salt, Zn(CH3COO)2 & sdot;2H2O, 3 COO) 2 & sdot;2H 2 O, and Eu2O3 2 O 3 nanopowder with different Zn/Eu ratios. The coatings were investigated by SEM, XRD, XPS, DRS, and photoluminescence analysis, and their photoactivity was studied in the degradation of two pollutants, lindane and methyl orange. The ZnO-Eu2O3 2 O 3 coatings were more photoactive than coatings containing only ZnO. Among the ZnO-Eu2O3 2 O 3 coatings, the photocatalyst with 2 wt% Eu2O3 2 O 3 showed the highest photoactivity for both pollutants. The incorporation of Eu3+ 3 + ions into the ZnO crystal lattice causes the appearance of oxygen vacancy defects and better charge separation in the ZnO-Eu2O3 2 O 3 coating. When the Eu2O3 2 O 3 concentration exceeds 2 wt%, the photoactivity decreases as additional centers for electron-hole pair recombination are created. It is shown that the main factor influencing the photoactivity of Eu-doped ZnO composite coatings is the amount of Eu3+ 3 + incorporated into the ZnO lattice.