Materials Chemistry Research Centre, Department of Chemistry, University College London, 20 Gordon Street, London, WC1H 0AJ, UK.
Chemistry. 2012 Oct 8;18(41):13048-58. doi: 10.1002/chem.201201859. Epub 2012 Sep 3.
It has often been suggested that anatase-rutile mixtures/composites synergistically enhance photocatalysis. However, in the case of dense thin-films containing an intimate mix of both anatase and rutile phases, such an effect has not been observed. In synthesising combinatorial films with graded film thickness and phase, and applying established photocatalytic mapping methods, we were able to assess how dense thin-films of intimately mixed anatase-rutile mixtures affect photocatalytic performance. We found that no photocatalytic synergy between anatase-rutile composites (29≤rutile %≤83) within such dense thin-film systems exists. In fact, an increased presence of rutile caused the photocatalytic activity to fall. This was explained by the unfavourable energetics in the multiple electron transfers required between several neighbouring rutile and anatase sites for the photo-generated electron to reach the material's surface; encouraging the trapping of electrons within the bulk and increasing the likelihood of charge recombination. The decrease in photocatalytic activity was found to vary linearly with rutile component.
人们常说锐钛矿-金红石混合物/复合材料协同增强光催化作用。然而，在含有锐钛矿和金红石相紧密混合的致密薄膜的情况下，尚未观察到这种效果。在通过合成具有分级膜厚和相的组合膜，并应用已建立的光催化映射方法，我们能够评估致密的锐钛矿-金红石混合物薄膜如何影响光催化性能。我们发现，在这种致密的薄膜体系中，锐钛矿-金红石复合材料（29≤金红石%≤83）之间不存在光催化协同作用。实际上，金红石的存在增加会导致光催化活性下降。这可以通过在光生电子到达材料表面所需的多个相邻金红石和锐钛矿之间的多次电子转移中存在不利的能量学来解释；这鼓励了电子在体相中的捕获，并增加了电荷复合的可能性。发现光催化活性的下降与金红石成分呈线性关系。
