Lead halide perovskite materials have attracted significant attention in the context of photovoltaics and other optoelectronic applications, and recently, research efforts have been directed to nanostructured lead halide perovskites. Collodial nanocrystals (NCs) of cesium lead halides (CsPbX3, X = Cl, Br, I) exhibit bright photoluminescence, with emission tunable over the entire visible spectral region. However, previous studies on CsPbX3 NCs did not address key aspects of their chemistry and photophysics such as surface chemistry and quantitative light absorption. Here, we elaborate on the synthesis of CsPbBr3 NCs and their surface chemistry. In addition, the intrinsic absorption coefficient was determined experimentally by combining elemental analysis with accurate optical absorption measurements. (1)H solution nuclear magnetic resonance spectroscopy was used to characterize sample purity, elucidate the surface chemistry, and evaluate the influence of purification methods on the surface composition. We find that ligand binding to the NC surface is highly dynamic, and therefore, ligands are easily lost during the isolation and purification procedures. However, when a small amount of both oleic acid and oleylamine is added, the NCs can be purified, maintaining optical, colloidal, and material integrity. In addition, we find that a high amine content in the ligand shell increases the quantum yield due to the improved binding of the carboxylic acid.

This review captures the synthesis, assembly, properties, and applications of copper chalcogenide NCs, which have achieved significant research interest in the last decade due to their compositional and structural versatility. The outstanding functional properties of these materials stems from the relationship between their band structure and defect concentration, including charge carrier concentration and electronic conductivity character, which consequently affects their optoelectronic, optical, and plasmonic properties. This, combined with several metastable crystal phases and stoichiometries and the low energy of formation of defects, makes the reproducible synthesis of these materials, with tunable parameters, remarkable. Further to this, the review captures the progress of the hierarchical assembly of these NCs, which bridges the link between their discrete and collective properties. Their ubiquitous application set has cross-cut energy conversion (photovoltaics, photocatalysis, thermoelectrics), energy storage (lithium-ion batteries, hydrogen generation), emissive materials (plasmonics, LEDs, biolabelling), sensors (electrochemical, biochemical), biomedical devices (magnetic resonance imaging, X-ray computer tomography), and medical therapies (photochemothermal therapies, immunotherapy, radiotherapy, and drug delivery). The confluence of advances in the synthesis, assembly, and application of these NCs in the past decade has the potential to significantly impact society, both economically and environmentally.

We report a procedure to prepare highly monodisperse copper telluride nanocubes, nanoplates, and nanorods. The procedure is based on the reaction of a copper salt with trioctylphosphine telluride in the presence of lithium bis(trimethylsilyl)amide and oleylamine. CuTe nanocrystals display a strong near-infrared optical absorption associated with localized surface plasmon resonances. We exploit this plasmon resonance for the design of surface-enhanced Raman scattering sensors for unconventional optical probes. Furthermore, we also report here our preliminary analysis of the use of CuTe nanocrystals as cytotoxic and photothermal agents.

Cu 2 ZnSnS 4 , based on abundant and environmental friendly elements and with a direct band gap of 1.5 eV, is a main candidate material for solar energy conversion through both photovoltaics and photocatalysis. We detail here the synthesis of quasi-spherical Cu 2 ZnSnS 4 nanoparticles with unprecedented narrow size distributions. We further detail their use as seeds to produce CZTS-Au and CZTS-Pt heterostructured nanoparticles. Such heterostructured nanoparticles are shown to have excellent photocatalytic properties toward degradation of Rhodamine B and hydrogen generation by water splitting. C urrent functional nanomaterials must meet numerous very demanding properties that cannot be realized with a unique compound. Thus, the use heterostructured nanomaterials or nanocomposites is generally required in a wide range of applications. In such multiphase materials, not only the properties of the compounds but also those of their interface have a determinant influence over their performance. In particular, an efficient photocatalytic system requires an intimate interface between two phases, a light-absorbing semiconductor and a co-catalyst. Such hybrid materials can be produced with composition control at the nanometer scale through the direct growth in solution of one of the compounds from the surface of the other, which acts as a seed.1 Such direct growth of the heterostructured nanomaterial ensures a fast and efficient charge transfer between the two phases.Solar energy conversion to electricity or its storage in renewable fuels is a particularly interesting application requiring the development of high-performance, environmental friendly, and cost-effective heterostructured materials. While several semiconductors have been proposed to harvest sunlight, 2 Cu 2 ZnSnS 4 (CZTS) uniquely combines both outstanding optoelectronic properties, with a direct band gap energy of 1.5 eV, and a composition based on elements that abound in the Earth's crust. Such an environmental friendly and low-cost material has been demonstrated to be an excellent light absorber in photovoltaic devices and to have a large potential for photodegradation of pollutants and for photocatalytic generation of hydrogen and other value-added chemicals.3 CZTS and related quaternary nanocrystals can currently be produced by different procedures. 4 However, due to the difficulties in tuning the composition, phase, size, and shape of such complex materials, the preparation of CZTS-based heterostructures and particularly CZTS-metal hybrid nanoparticles has not yet been achieved.In the present work, we detail a procedure to produce colloidal CZTS-metal heterostructured nanoparticles with strongly electrically coupled interfaces. Au and Pt were the metals chosen due to their potential for plasmonic enhancement (Au) and a proper over-potential for hydrogen generation (Pt) (Scheme 1). Heterostructures were tested for photodegration of pollutants in solution using Rhodamine B as the model system, and for photocatalytic hydrogen generation from wate...