A facile template-free approach for the large-scale solid-phase synthesis of cds nanostructures and their excellent photocatalytic performance
Date
2011
Authors
Apte, S.K.
Garaje, S.N.
Mane, G.P.
Vinu, A.
Naik, S.D.
Amalnerkar, D.P.
Kale, B.B.
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Journal article
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Small, 2011; 7(7):957-964
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Abstract
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/NH2CSNH2 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 H2 generation and organic dye degradation are performed under visible-light irradiation. The maximum H2 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. The hexagonal phase of wurtzite nanostructured CdS with cubelike morphology is obtained by a one-pot solid-state method. CdS with a uniform size of 5-7 nm can be produced on a large scale. This nanostructured CdS shows excellent photocatalytic activity for hydrogen production and organic dye degradation under solar light. The CdS can be used to make thin films for solar-cell applications as well as photoconducting devices.
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Copyright 2011 Wiley-VCH