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We report here a new ternary chalcogenide material, cadmium lanthanum sulfide (CdLa2S4) produced using a facile hydrothermal method at 433 K. The effect of the solvent on the morphology of the CdLa2S4was demonstrated for the first time. The prima facieobservations revealed the formation of highly crystalline hexagonal structures in the form of flowers in aqueous medium. The flowers comprise hexagonal columns ∼300 nm in diameter and 1–1.2 μm in length. All the hexagonal structures have a sharp tip with a cavity of 10 nm and are almost equal in size. The nanoprisms have an average base size of 35 nm with 35 nm edges, and the nanowires have a diameter of 10–15 nm; both were obtained in methanol. Crystal and electronic structure calculations were performed using the Vienna ab initiosimulation package (VASP) based on density functional theory (DFT). Considering the band gap of pristine CdLa2S4in the visible region (2.3 eV), we have demonstrated CdLa2S4as a photocatalyst for the production of H2under solar light. Nanostructured CdLa2S4prisms gave the maximum hydrogen production, i.e.2552 μmol h−1. Being a stable ternary nanostructured metal sulfide (with nanohexagons, nanoprisms, nanowires), CdLa2S4may have other potential prospective applications in solar cells and optoelectronic devices. [ABSTRACT FROM AUTHOR]

We have demonstrated the synthesis of nanostructured CdIn2S4with a fascinating ‘marigold flower’ morphology using a hydrothermal method, and mixed morphologies (flowers, spheres and pyramids) using a microwave method. In the microwave synthesis, the product was formed within 15 min, whereas by the hydrothermal method more than 24 h was required. In the microwave method, various capping agents were used that result in different particle morphologies. Hydrothermal formation of crystalline CdIn2S4nanotubes in methanol showed a significant effect of reaction medium on morphology. Synthesis of these crystalline CdIn2S4nanopyramids and ‘marigold flowers’ has also been demonstrated using microwave synthesis for the first time. An XRD study showed a cubic spinel structure for CdIn2S4prepared by both methods. The band gap for CdIn2S4was 2.27 eV when synthesized using the microwave method, and 2.23 eV using the hydrothermal method, implying that the microwave method produces a lower particle size than the hydrothermal method. A noteworthy aspect of this work is that we obtained novel ternary chalcogenide hierarchical nanostructures by simple hydrothermal and microwave methods. Considering that the band gap of the hierarchical CdIn2S4is within the visible region, we compared its ability to photocatalytically degrade methylene blue (MB) with that of CdS. The marigold flowers, nanoparticle spheres and nanopyramids of CdIn2S4synthesised by microwave method gave almost 30% enhancement in the degradation of MB as compared to CdS under direct sunlight. This is of importance, considering that CdIn2S4has potential for applications in solar energy conversion and opto-electronic devices. [ABSTRACT FROM AUTHOR]

The present work is the investigation of our novel approach to designing quantum dot–glass nanosystems by confining nano CdS in designated glass and the first employment of such a quantum dot system in solar hydrogen production. The CdS quantum dots were grown in a special glass matrix, which involved a sequence of steps. The obtained glass was of uniformly bright yellow in color and the bulk glass was pulverized to a fine powder of micron size particles. The glass powder was characterized structurally and morphologically. X-Ray diffraction and electron diffraction patterns reveal a hexagonal crystallite system for the CdS quantum dots. Field emission scanning electron microscopy, transmission electron microscopy, X-ray photoelectron spectroscopy, X-ray fluorescence spectroscopy and chemical leaching with HCl studies demonstrate that the 2.5 nm size CdS quantum dots distribute homogeneously in a monodispersed form in the glass domain and on the surface with a “partially embedded exposure” configuration. This disposition imparts an excellent photostability against photocorrosion and also a facile catalytic function. Therefore, even a very small amount of CdS quantum dots (0.005 g per gram of glass powder) is able to photodecompose H2S under visible light (λ≥ 420 nm) both in alkaline and pure aqueous media and produce solar hydrogen with markedly high quantum yields of 17.5 and 11.4%, respectively at 470 nm. Salient features like reusability after simple washing, corrosionless-stability and remarkable catalytic activity of this quantum dot–glass nanosystem are brought forth by our novel catalyst design and are much acclaimed in large scale solar H2 production. [ABSTRACT FROM AUTHOR]