Sodium-Naphthalenide-Driven Synthesis of Base-Metal Nanoparticles and Follow-up Reactions.

Mo(0), W(0), Fe(0), Ru(0), Re(0), and Zn(0) nanoparticles­essentially base metals­are prepared as a general strategy by a sodium naphthalenide ([NaNaph])-driven reduction of simple metal chlorides in ethers (1,2-dimethoxyethane (DME), tetrahydrofuran (THF)). All the nanoparticles have diameters ≤10 nm, and they can be obtained either as powder samples or long-term stable suspensions. Direct follow-up reactions (e.g., Mo(0)+S8, FeCl3+AsCl3, ReCl5+MoCl5), moreover, allow the preparation of MoS2, FeAs2, or Re4Mo nanoparticles of similar size as the pristine metals (≤10 nm).

Light-induced modification of silver nanoparticles with functional polymers.

A mild, efficient and ambient temperature photochemical approach for the synthesis of silver nanoparticle core-shell structures employing a zwitterionic polymer as well as polyethylene glycol is presented.

Tungsten nanoparticles from liquid-ammonia-based synthesis.

Tungsten nanoparticles were obtained from liquid-ammonia-based synthesis via reduction of WCl6 with dissolved sodium. The W(0) nanoparticles exhibit a diameter of 1-2 nm and can be dispersed in alkanes, showing a grayish-orange color due to red-shifted plasmon resonance absorption.

Quantum-confined GaN nanoparticles synthesized via liquid-ammonia-in-oil-microemulsions.

GaN nanoparticles, 3-4 nm in size, are synthesized in a microemulsion using liquid ammonia as the polar droplet phase. Surprisingly, GaN is readily crystalline although prepared at -40 °C. The nanoparticles show a band gap of 4.4 eV as well as light emission with its maximum at 336 nm. Both confirm the expected quantum-confinement effect.

Ammonia-in-oil-microemulsions and their application.

Liquid ammonia on the nanoscale: Ammonia-in-oil microemulsions are used to synthesize Bi, Re, CoN, and GaN nanoparticles, which can be obtained without further thermal treatment. These microemulsions are as reproducible and simple as their water-in-oil conterparts, with the exception of the required low temperature of -40 °C.

Bulk heterojunction nanomorphology of fluorenyl hexa-peri-hexabenzocoronene-fullerene blend films.

In this study, the nanomorphology of fluorenyl hexa-peri-hexabenzocoronene:[6,6]-phenyl C61-butyric acid methyl ester (FHBC:PC61BM) absorber layers of organic solar cells was investigated. Different electron microscopical techniques, atomic force microscopy, and grazing incidence wide-angle X-ray scattering were applied for a comprehensive nanomorphology analysis. The development of the nanomorphology upon sample annealing and the associated change of the device performance were investigated. It was shown that the annealing process enhances the phase separation and therefore the bulk heterojunction structure. Due to π-π stacking, the FHBC molecules assemble into columnar stacks, which are already present before annealing. While the nonannealed sample consists of a mixture of homogeneously distributed PC61BM molecules and FHBC stacks with a preferential in-plane stack orientation, crystalline FHBC precipitates occur in the annealed samples. These crystals, which consist of hexagonal arranged FHBC stacks, grow with increased annealing time. They are distributed homogeneously over the whole volume of the absorber layer as revealed by electron tomography. The FHBC stacks, whether in the two phase mixture or in the pure crystalline precipitates, exhibit an edge-on orientation, according to results from grazing incidence wide-angle X-ray scattering (GIWAXS), dark-field transmission electron microscopy (DF TEM) imaging and selective area electron diffraction (SAED). The best solar cell efficiencies were obtained after 20 or 40 s sample annealing. These annealing times induce an optimized degree of phase separation between donor and acceptor material.