Thiosulfate leaching of gold—A review

Semiconductor nanocrystals possess size-dependent properties, which make them interesting candidates for a variety of applications, e.g., in solar energy conversion, lighting, display technology, or biolabelling. However, many of the best studied nanocrystalline materials contain toxic heavy metals; this seriously limits their potential for widespread application. One of the possible less toxic alternatives to cadmium- or lead-containing semiconductors is copper indium disulfide (CIS), a direct semiconductor with a bandgap in the bulk of 1.45 eV and a Bohr exciton radius of 4.1 nm. This Review gives an overview of the methods developed during the last years to synthesize CIS nanocrystals and summarizes the possibilities to influence their shape, composition and crystallographic structure. Also the potential of the application of CIS nanocrystals in biolabellling, photocatalysis, solar energy conversion, and light-emitting devices is discussed.

Synthesis and Application of Colloidal CuInS2 Semiconductor Nanocrystals

Gold nanoparticles and their arrays are some of the most studied nanomaterials, with promising applications in many fields such as electronics, optoelectronics, catalysis and biology. In order to protect bare gold nanoparticles from aggregation, to manipulate the optical, electronic and catalytic properties of the gold core, as well as to control interfacial properties, the gold nanoparticles are generally capped by an organic layer. Previous studies [C.D. Bain, G.M. Whitesides, J. Am. Chem. Soc. 110 (1988) 3665-3666] have revealed that many phenomena (e.g., wetting, friction and adhesion), are sensitive to the top few angstroms of a surface. The interfacial properties of a gold surface derivatized with a self-assembled monolayer will thus be dictated by the functionalities present on the outer side of the monolayer. The synthesis, functionalization and surface structure of monolayer-protected gold nanoparticles have been intensively studied in recent times [M.-C. Daniel, D. Astruc, Chem. Rev. 104 (2004) 293-346]. In addition, the aggregation and dispersion of colloidal nanoparticles is one of the key issues related to their potential applications. The forces that govern the colloid stability of nanoparticle dispersions, and how to control them, have yet to be fully investigated. Here special attention has been paid to control of colloid stability using external stimuli. In this feature article, the following five areas are reviewed: synthesis and applications of nanostructured particles; formation and structure of self-assembled monolayer protected gold nanoparticles; colloid stability-DLVO and non-DLVO forces; photochemistry, photochromism and pyrimidine; and manipulation of colloid stability with external stimuli.

Functionalized gold nanoparticles: Synthesis, structure and colloid stability

The development of copper chalcogenide based nanomaterials as promising candidates for sustainable energy materials, due to their environmental compatibility and low toxicity, is presented and discussed in this review. Different solution syntheses have recently been developed for the low-cost preparation of copper chalcogenide nanocrystals, and their unique properties derived from copper deficiencies were investigated with much progress. The notorious compositional instability and defect formation of copper chalcogenide nanocrystals have been healed by forming donor–acceptor pairs in ternary and quaternary chalcogenide based nanocrystals, especially in copper zinc tin sulfides (CZTS). In addition to their use as light absorbers in solar cells, copper chalcogenide nanocrystals have also been utilized in different applications, such as electrode materials in Li ion batteries and high efficiency counter electrodes in dye/quantum dot sensitized solar cells as well as for NIR photothermal therapy. All relate to their unique copper deficiency properties. The copper chalcogenide based nanomaterials are believed to be sustainable materials for future energy applications once the syntheses and property investigations have led to a more complete understanding of their physics.

Development of plasmonic semiconductor nanomaterials with copper chalcogenides for a future with sustainable energy materials

Spent lithium-ion battery recycling - Reductive ammonia leaching of metals from cathode scrap by sodium sulphite.

Preferential leaching of cobalt, nickel and copper from cobalt-rich ferromanganese crusts with ammoniacal solutions using ammonium thiosulfate and ammonium sulfite as reducing agents

CuInS2 nanoparticles (NPs) have been synthesized via thermal decomposition of metal-thiolate in high boiling temperature solvent. This method does not require toxic, unstable and expensive raw materials. Nearly monodispersed NPs with average diameter ranging from 1.8 to 2.8 nm are obtained. The NPs are found to be compositionally copper rich, Cu:In:S=1.6:1.0:1.3. They exhibit size-dependent optical properties such as photoluminescence (PL) and optical absorption, indicating quantum confinement effects. In PL spectra, the stokes-shifts (∼300 meV) from the absorption band edge and their broad PL spectra indicate that PL is ascribed to a donor-acceptor transition. These results demonstrate that chalcopyrite NPs are promising candidates for luminous and solar cell materials.

Takahide Wakamatsu

Papers

Preferential leaching of cobalt, nickel and copper from cobalt-rich ferromanganese crusts with ammoniacal solutions using ammonium thiosulfate and ammonium sulfite as reducing agents

Synthesis of Chalcopyrite Nanoparticles via Thermal Decomposition of Metal-Thiolate

Facile synthesis of nearly monodispersed copper sulfide nanocrystals

The role of alkaline earth cations in flotation separation of quartz from feldspar

Adsorption of 2-mercaptobenzothiazole onto pyrite