Enhanced Photoelectrocatalytic Reduction and Removal of Atrazine: Effect of Co-Catalyst and Cathode Potential

Photoelectrocatalytic (PEC) reduction and removal of atrazine, one typical endocrine disruptor chemical, was achieved on Pd quantum dots modified TiO₂ nanotubes (PdQDs@TiO₂NTs) under regulating potentials. Compared with that on TiO₂NTs, the PEC reduction efficiency of atrazine on PdQDs@TiO₂NTs significantly increased, mainly attributed to the reduced electron transfer resistance, longer lifetime of the photogenerated electrons and the faster electron injection from the catalyst to atrazine in the solution. Meanwhile, PdQDs could also function as cocatalyst so that the electrocatalytic activity of PdQDs@TiO₂NTs was evidently improved. Moreover, the investigation indicated that the applied potential not only played important role in accelerating the separation of photogenerated electrons and holes, but also with the increment of the cathodic potential, the PEC reduction mechanism of atrazine underwent the variation of electro-assisted photocatalysis, synergetic photoelectro-catalysis, and photoassisted electro-catalysis. A highest atrazine PEC reduction efficiency was achieved as 99.5% on PdQDs@TiO₂NTs in about 5 h under the potential of -1.3 V vs. SCE, whereas the highest synergetic effect of photo- and electro- catalysis was achieved at a lower potential of -0.9 V vs. SCE.