Preparation And Photocatalytic Performances Of TiO₂Nanotubes/Polyoxometalates Composite Film

Titania （TiO₂） nanotubes, as excellent semiconductor materials, have beenwidely used inenvironmental remediation, solar photovoltaic cells, and water splitting devices. However,most of these applications suffer from the dissatisfactory quantum efficiency due to the highelectron-hole recombination rate in the single TiO₂nanotubes. Polyoxometalates （POMs） canact as an efficient electron acceptor to suppress electron hole recombinationcan and thenimprove the photocatalytic and photovoltaic properties.In this work, a high density and well-ordered TiO₂nanotube array was prepared byelectrochemical anodization technique. The composite film containing TiO₂nanotubes andPOMs (H₃PW₁₂O₄₀, denoted as PW₁₂) was prepared by electrodeposition. First, we fabricatedthe TiO₂-POMs composite film by electrodeposition for2h in a solution of0.001M PW₁₂.The photocatalytic properties of the TiO₂nanotubes and the TiO₂-POMs composite film wereevaluated by the decomposition of nitrobenzene. As a result, the TiO₂-POMs composite filmshowed much higher photocatalytic activity than pure TiO₂nanotubes. These demonstratedthat the modification of the TiO₂nanotubes with POMs can provide an enhancedphotocatalytic activity.Second, we fabricated the TiO₂-POMs composite film by electrodeposition for2h in asolution of0.005M PW₁₂, and investigated its photoelectrocatalytic activity for methanol andhydrazine. The TiO₂-POMs composite film displayed more significant photoelectrocatalyticactivity for methanol and hydrazine than the TiO₂nanotubes.At last,The TiO₂nanotubes and TiO₂-POMs composite film were fabricated asphotoanodes.Their photovoltaic properties were investigated by assembling the solar celldevice.The results demonstrated that the TiO₂-POMs composite film showed the higherpower conversion efficiency than the TiO₂nanotubes.These results suggest that the modification of the TiO₂nanotubes with POMs caneffectively retard electron hole recombination, thus enhancing the photocatalytic andphotovoltaic properties. The results obtained from this study show that the combination ofsemiconductors with the appropriate POMs is a promising strategy for improvingphotoelectrochemical performance of semiconductors.