Determination of the phase diagrams for the nanocrystalline forms of materials is crucial for our understanding of nanostructures and the design of functional materials using nanoscale building blocks. The ability to study such transformations in nanomaterials with controlled shape offers further insight into transition mechanisms and the influence of particular facets. Here we present an investigation of the size-dependent, temperature-induced solid-solid phase transition in copper sulfide nanorods from low-to high-chalcocite. We find the transition temperature to be substantially reduced, with the high chalcocite phase appearing in the smallest nanocrystals at temperatures so low that they are typical of photovoltaic operation. Size dependence in phase transformations suggests the possibility of accessing morphologies that are not found in bulk solids at ambient conditions. These otherwise-inaccessible crystal phases could enable higher-performing materials in a range of applications, including sensing, switching, lighting, and photovoltaics.
Squaring the circle: Carbon monoxide was used to grow faceted cube‐like platinum tips on semiconductor nanorods (see scheme). These novel hybrid structures reveal a new degree of synthetic control and might allow control over the catalytic activity of nanoscale photocatalysts by adding defined faceting.
Reine Kristalle: Durch Ionenaustausch an Halbleiterkristallen wurden Materialien mit unbefriedigenden optoelektronischen Eigenschaften wie einer geringen Photolumineszenz‐Quantenausbeute erhalten. Der Grund für die geringe Quantenausbeute dieser Kristalle sind Unreinheiten. Nanostrukturen, die durch Kationenaustausch erhalten wurden, konnten nach dem Austausch gereinigt werden und lieferten qualitativ hochwertige Kristalle (siehe Bild).
Auf die Spitze getrieben: Kohlenmonoxid wurde dazu verwendet, facettierte würfelähnliche Platinspitzen auf Halbleiternanostäbchen zu erzeugen (siehe Schema). Diese neuartigen Hybridstrukturen zeichnen sich durch einen zuvor unerreichten Grad an präparativer Kontrolle aus und könnten es ermöglichen, die katalytische Aktivität nanoskaliger Photokatalysatoren mithilfe von definierter Facettierung zu steuern.
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