A facile template-free approach for fabrication of flower-like CdS: the evolutionary process of the structure and the performance of photocatalytic activity

Abstract

Uniform flower-like CdS was fabricated successfully using a facile hydrothermal approach without templates or additives. The formation process of the flower-like structures was investigated in detail.The as-prepared flower-like CdS exhibited good photocatalytic activity for the photodegradation of various organic dyes.Semiconductor photocatalysis technology has been considered a promising strategy to solve environmental issues through the photodegradation of organic pollutants because it is an eco-friendly, low-cost and sustainable treatment. 1 For example, anatase TiO 2 is the most studied semiconductor as an environmental cleanup photocatalyst owing to its photoactivity, stability, biocompatibility, and low cost. 2-4 On the other hand, TiO 2 has a high band gap and responds to UV light only. 1 Therefore, TiO 2 can only utilize a small part (<5%) of the solar spectrum, which limits its practical application as a photocatalyst. Therefore, considerable efforts have been made to find efficient photocatalysts that can effectively degrade organic pollutants under visible light irradiation. As an important II-VI semiconductor, cadmium sulfide (CdS) is an ideal visible light driven photocatalyst because of its narrow and direct band gap (at room temperature is approximately 2.42 eV), which corresponds well to the solar spectrum. Therefore, CdS has been extensively studied in diverse photocatalytic fields, such as reduction of nitro organics, water splitting and dye degradation. [5][6][7][8] The morphology and size of a semiconductor catalyst have a great effect on photocatalytic activity because reactants are in contact with the photocatalyst surface, where the catalytic reaction takes place. For CdS nanostructures, the morphology and size play important roles in the optical and physical properties. 9 Therefore, chemists and material scientists have made considerable efforts to control the morphology and size of CdS nanomaterials, and a range of CdS nanostructures have been obtained, such as quantum dots, 10,11 nanospheres, 12,13 nanorods, 13,14 nanowires, 15,16 nanobelts, 17,18 nanosheets, 19 nanotubes, 20 nanoboxes, 21 hierarchical nanostructures, 22-26 hollow nanostructures, 27,28 and flower-like nanostructures. 8,29 To fabricate CdS nanostructures with the desired morphology and different sizes, various synthetic approaches have been developed, such as chemical vapor deposition, 30 thermal evaporation, 31 thermal decomposition, 32,33 the vapor-liquid-solid process, 18,34 electrodeposition, 16 the template method, 21,35 microwave-assisted aqueous synthesis, 36 solvothermal synthesis, 37-39 and the hydrothermal method. 29,40-42 Of these, the hydrothermal method has been demonstrated to be an effective approach for fabricating CdS nanomaterials. For example, Salavati-Niasari et al. have reported the size-controlled synthesis of a CdS nanostructure by a mild and simple hydrothermal method. 29 Herein, we show a facile hydrothermal approach to synthesize flower-like CdS nanomaterials with uniform size and good dispersibi...

Morphology‐ and Size‐Controlled Fabrication of CdS from Flower‐Like to Spherical Structures and their Application for High‐Performance Photoactivity

“…For example, Yu et al have synthesized the morphology‐controlled CdS photocatalysts by adjusting the sulfur source and solvent, explaining the formation mechanism and influence of different morphologies and the nature of solvents on the activity . Wang et al synthesized flower‐like CdS nanomaterials with uniform size and good dispersibility by a facile hydrothermal approach, exhibiting the excellent photocatalytic activity for the degradation of various organic dyes . Zhong et al prepared high quality CdS nanoribbons by low pressure thermal evaporation which can be utilized in optoelectronic devices .…”