Performance in degradation of tetracycline hydrochloride over Tb-doped Bi2WO6
As a photocatalyst,Bi2WO6 has the disadvantages of a narrow light response range and low efficiency in separating photogenerated electron-hole pairs.To address these drawbacks,Tb-doped Bi2WO6(Tb-BWO)was synthesized using hydrothermal method.Its photocatalytic performance was evaluated by degrading tetracycline hydrochloride(TCH)under visible light irradiation.The improvement in photocatalytic activity,degradation mechanism and stability of the photocatalyst were analyzed.Results indicated that at 1.2％Tb cation concentration,1.2Tb-BWO showed the highest photocatalytic activity,degrading 60.1％of TCH after 240 min of reaction.The enhanced activity of Tb-BWO was attributed to the Tb ion doping introducing impurity levels near the conduction band level ofBWO,which reduced the band gap and promoted photogenerated electron-hole pair generation.Oxygen vacancies adsorbed oxygen and reacted with trapped electrons to form strong oxidant superoxide radicals(·O2),thereby inhibiting photogenerated electron-hole pair recombination.Photogenerated electrons reduced Tb4+to Tb3+,while Tb34 was oxidized to Tb4+ and ·O2- by O2,aiding in the separation of photogenerated electron-hole pairs.TCH was decomposed by active radicals ·O2-and h+,with·O2-playing a crucial role.The catalyst's stability was maintained by cleaning the adsorbed TCH on the surface with ethanol after each cycle.
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