Kar Arik, Sain Sumanta, Kundu Simanta, Bhattacharyya Arka, Kumar Pradhan Swapan, Patra Amitava
Department of Materials Science, Indian Association for the Cultivation of Science, Kolkata 700 032 (India); Present address: Department of Chemistry, University of Cambridge (UK).
Chemphyschem. 2015 Apr 7;16(5):1017-25. doi: 10.1002/cphc.201402864. Epub 2015 Feb 2.
Tuning the functional properties of nanocrystals is an important issue in nanoscience. Here, we are able to tune the photocatalytic properties of SnO2 nanocrystals by controlling their size and shape. A structural analysis was carried out by using X-ray diffraction (XRD)/Rietveld and transmission electron microscopy (TEM). The results reveal that the number of oxygen-related defects varies upon changing the size and shape of the nanocrystals, which eventually influences their photocatalytic properties. Time-resolved spectroscopic studies of the carrier relaxation dynamics of the SnO2 nanocrystals further confirm that the electron-hole recombination process is controlled by oxygen/defect states, which can be tuned by changing the shape and size of the materials. The degradation of dyes (90%) in the presence of SnO2 nanoparticles under UV light is comparable to that (88%) in the presence of standard TiO2 Degussa P-25 (P25) powders. The photocatalytic activity of the nanoparticles is significantly higher than those of nanorods and nanospheres because the effective charge separation in the SnO2 nanoparticles is controlled by defect states leading to enhanced photocatalytic properties. The size- and shape-dependent photocatalytic properties of SnO2 nanocrystals make these materials interesting candidates for photocatalytic applications.
调节纳米晶体的功能特性是纳米科学中的一个重要问题。在此，我们能够通过控制SnO₂纳米晶体的尺寸和形状来调节其光催化性能。利用X射线衍射（XRD）/Rietveld方法和透射电子显微镜（TEM）进行了结构分析。结果表明，与氧相关的缺陷数量会随着纳米晶体尺寸和形状的变化而改变，这最终会影响它们的光催化性能。对SnO₂纳米晶体载流子弛豫动力学的时间分辨光谱研究进一步证实，电子 - 空穴复合过程受氧/缺陷态控制，而氧/缺陷态可通过改变材料的形状和尺寸来调节。在紫外光下，SnO₂纳米颗粒存在时染料的降解率（90%）与标准TiO₂德固赛P - 25（P25）粉末存在时的降解率（88%）相当。纳米颗粒的光催化活性明显高于纳米棒和纳米球，因为SnO₂纳米颗粒中的有效电荷分离受缺陷态控制，从而导致光催化性能增强。SnO₂纳米晶体尺寸和形状依赖的光催化性能使这些材料成为光催化应用的有趣候选材料。
