Photocatalytic activity of water-dispersible all-inorganic Si quantum dots (QDs) with heavily B and P codoped shells was studied by monitoring bleaching of Rhodamine B (RhB) in a mixture aqueous solution of Si QDs and RhB under light irradiation. The size of Si QDs was changed from 2.8 to 9.0 nm. A strong size dependence was observed in the dissociation rate of RhB. The observed size dependence of the rate could be well explained by the Marcus theory, which considers charge transfer from the LUMO of Si QDs to that of RhB. Quenching of the photoluminescence (PL) and the shortening of the PL lifetime of Si QDs due to the electron transfer to RhB were also observed. From these two approaches, we demonstrated that the quantum size effect plays a crucial role for the enhanced photocatalytic activity of Si QDs.

中文翻译：

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胶体硅量子点的尺寸依赖性光催化活性

通过在光照射下监测罗丹明B（RhB）在Si QDs和RhB的混合水溶液中的漂白，研究了重掺杂B和P共掺杂壳的水分散性全无机Si量子点（QDs）的光催化活性。Si QD的尺寸从2.8 nm更改为9.0 nm。在RhB的解离速率中观察到强烈的大小依赖性。Marcus理论可以很好地解释所观察到的速率的大小依赖性，该理论考虑了电荷从Si量子点的LUMO转移到RhB的电荷。还观察到由于电子转移到RhB导致Si量子点的光致发光（PL）淬灭和PL寿命缩短。从这两种方法，我们证明了量子尺寸效应对于提高硅量子点的光催化活性起着至关重要的作用。