Centre for Materials for Electronics Technology, Department of Information and Technology, Govt. of India, Panchawati off Pashan Road, Pune 411008, India.
Small. 2011 Apr 4;7(7):957-64. doi: 10.1002/smll.201002130. Epub 2011 Mar 8.
The simple, template-free, low-temperature, large-scale synthesis of nanostructured CdS with the hexagonal wurtzite phase from bulk cadmium oxide under solid-phase conditions is demonstrated for the first time. The novel approach involves the homogenization of cadmium oxide (CdO) and thiourea in various stoichiometric ratios at moderate temperature. Among the different molar ratios of CdO and thiourea studied, the CdO/NH(2) CSNH(2) molar ratio of 1:2 is found to be the best to obtain highly pure CdS. The obtained CdS nanostructures exhibit excellent cubic morphology and high specific surface area with a particle size in the range of 5-7 nm. The bandgap of the nanostructured CdS is in the range of 2.42 to 2.46 eV due to its nanocrystalline nature. In photoluminescence studies, emission is observed at 520.34 and 536.42 nm, which is characteristic of the greenish-yellow region of the visible spectrum. Considering the bandgap of the CdS is within the visible region, the photocatalytic activity for H(2) generation and organic dye degradation are performed under visible-light irradiation. The maximum H(2) evolution of 2945 μmol h(-1) is obtained using nanostructured CdS prepared in the 1:2 ratio, which is three times higher than that of bulk CdS (1010 μmol h(-1) ). CdS synthesized using the 1:2 molar ratio shows maximum methylene blue degradation (87.5%) over a period of 60 min, which is approximately four times higher than that of bulk CdS (22%). This amazing performance of the material is due to its nanocrystalline nature and the high surface area of the CdS. The proposed simple methodology is believed to be a significant breakthrough in the field of nanotechnology, and the method can be further generalized as a rational preparation scheme for the large-scale synthesis of various other nanostructured metal sulfides.
首次在固相条件下，通过块状氧化镉（CdO）在模板自由、低温、大规模条件下合成出六方纤锌矿结构纳米硫化镉（CdS）。该新方法涉及在中等温度下将 CdO 和硫代乙酰胺（thiourea）按不同化学计量比均匀混合。在所研究的不同 CdO 和硫代乙酰胺摩尔比中，发现 CdO/NH2CSNH2 的摩尔比为 1:2 时最有利于获得高纯度的 CdS。所得到的 CdS 纳米结构具有极好的立方形态和高比表面积，粒径在 5-7nm 范围内。由于纳米晶的特性，纳米结构 CdS 的带隙在 2.42 到 2.46eV 范围内。在光致发光研究中，在 520.34 和 536.42nm 处观察到发射，这是可见光光谱中绿黄色区域的特征。考虑到 CdS 的带隙在可见光范围内，在可见光照射下进行了 H2 生成和有机染料降解的光催化活性研究。使用 1:2 摩尔比制备的纳米结构 CdS 获得了 2945μmol h-1 的最大 H2 释放量，是块状 CdS（1010μmol h-1）的三倍。使用 1:2 摩尔比合成的 CdS 在 60 分钟内显示出最大的亚甲基蓝降解（87.5%），是块状 CdS（22%）的四倍。该材料的这种惊人性能归因于其纳米晶性质和 CdS 的高表面积。所提出的简单方法被认为是纳米技术领域的重大突破，该方法可以进一步推广为各种其他纳米结构金属硫化物的大规模合成的合理制备方案。
