Rare earth (Gd, La) co-doped ZnO nanoflowers for direct sunlight driven photocatalytic activity

In this work Gd/La@ZnO nanoflower photocatalyst has been successfully synthesized by a co-precipitation method and applied for rhodamine B (Rh B) and tetracycline (TCN) degradation under direct sunlight irradiation. The doping of rare earth elements enhances the optical absorption ability of ZnO to visible-light region (401 nm) from UV region (390 nm). In addition, the co-doped ZnO nanoflower exhibits lower charge recombination efficiency and it was confirmed by photoluminescence emission analysis. Moreover, the co-doped ZnO nanoflower exhibits the maximum degradation efficiency of 91% for Rh B and 74% for TCN under sunlight irradiation. The calculated synergistic index of co-doped ZnO is higher than pure ZnO. The production of reactive radicals was confirmed by terephthalic acid (TA) and nitro-blue tetrazolium (NBT) test. The holes and hydroxyl (•OH) radicals play the major role for degradation reaction and it was confirmed by scavenger’s test. Moreover, the recycling test confirmed the stability of the photocatalyst. Highly active and stable rare earth (Gd and La) co-doped ZnO nanoflower has been prepared for photocatalytic organic pollutant degradation.