Germanium Nanomaterials Research Articles

Characterization of Germanium Nanoparticles from Arylgermanium Trihydrides.

Germanium is a promising basis for nanomaterials due to its low toxicity and valuable optical and electronic properties. However, germanium nanomaterials have seen little research compared to other group 14 elements due to unpredictable chemical behavior and high costs. Here, we report the dehydrocoupling of o-tolylgermanium trihydride to amorphous nanoparticles. The reaction is facilitated through reflux at 162 °C and can be accelerated with an amine base catalyst. Through cleavage of both H2 and toluene, new Ge-Ge bonds form. This results in nanoparticles consisting of crosslinked germanium with o-tolyl termination. The particles are 2-6 nm in size and have masses above approximately 3500 Da. The organic substituents are promising for further functionalization. Combined with strong absorption up to 600 nm and moderate solubility and air stability, there are numerous possibilities for future applications.

Amorphous Germanium Nanomaterials as High‐Performance Anode for Lithium and Sodium‐Ion Batteries

AbstractAmorphous germanium (a‐Ge) is a promising anode material for lithium and sodium‐ion batteries (LIBs and SIBs) due to its higher capacity than traditional graphite materials. Herein, a method to prepare the a‐Ge nano‐materials with a particle size ≈10 nm is proposed by decomposing the CaGe Zintl phase at room temperature. For LIBs, a‐Ge has a high‐capacity retention of 80% even after 180 cycles (1375 mAh g−1). When employed as the anode for SIBs, two‐dimensional composites with the a‐Ge supported on the graphite nanosheets (a‐Ge@GNS) is configured, and a high reversible capacity of 526 mAh g−1 after 120 cycles is achieved. The preparation of such high‐performance amorphous Ge nanomaterials demonstrated in this work is low‐cost and environmentally‐friendly, and compared with other methods it is especially suitable for scaling‐up or mass production.

Germanium Crystalline Nanomaterials for Li-Ion Storage Prepared by Decomposing LiZnGe in Air.

Germanium nanomaterials are important for their potential applications in many fields. However, current synthetic technologies usually involve either high-cost explosive reagents or complicated facilities, which make the mass production especially challenging. In this report, a method was developed to synthesize nano-Ge materials conveniently, realized by decomposing LiZnGe in air at room temperature. The process is nontoxic, inexpensive, and, most of all, very suitable for large-scale production in combination with ball milling. The as-prepared Ge nanomaterials are crystalline whose structures can be flexibly tuned through the ball milling syntheses. As the lithium-ion battery anode, such Ge nanomaterials exhibited long-term cycle ability with high specific capacity as well as excellent rate performance. These results not only provided a very efficient way to prepare nano-Ge in lab or even promising industry production but also suggested a universal method in synthesizing the tetrels elemental nanomaterials.

Radical-Initiated and Thermally Induced Hydrogermylation of Alkenes on the Surfaces of Germanium Nanosheets

The synthesis of germanium nanomaterials with well-defined surface chemistry is of considerable interest because of not only general scientific curiosity but also their vast potential in optoelectronics, energy storage, and the semiconductor industry. Herein, we report a straightforward preparative route that yields hydride-terminated germanium nanosheet (H-GeNS) monolayers via sonochemical exfoliation of hydride-terminated germanane flakes (HGe-flakes) derived from crystalline CaGe2. We subsequently show that these freestanding H-GeNSs are readily functionalized by radical-initiated and thermally induced hydrogermylation. Furthermore, we demonstrate that following functionalization the crystal structure of the GeNSs remains intact, and the introduction of organic moieties to the GeNS surfaces imparts improved thermal stability and solvent compatibility.

Solution Synthesis, Surface Passivation, Optical Properties, Biomedical Applications, and Cytotoxicity of Silicon and Germanium Nanocrystals.

Silicon and germanium nanocrystals (NCs) are attractive materials owing to their unique size and surface-dependent optical properties. The optical properties of silicon and germanium NCs make them highly suitable for a range of applications, including bioimaging, light-emitting diodes, and solar cells. In this review, the solution synthesis, surface passivation, optical properties, biomedical applications, and cytotoxicity of silicon and germanium NCs are compared and contrasted. Over the last 10 years, synthetic protocols have improved considerably, with size control readily achieved. Investigations have begun into a range of silicon and germanium nanostructures, including doped, alloy, and metal-semiconductor hybrid NCs, which represent the next generation of silicon and germanium nanomaterials. Silicon and germanium NCs are actively researched for a wide array of biomedical applications, including, long-term in vivo cellular imaging, fluorescent nanocarriers for drug delivery, and as contrast agents for magnetic resonance imaging (MRI). Cytotoxicity studies have shown the low toxicity of Si NCs, while demonstrating that Ge NCs are less toxic than CdSe NCs at similar concentrations, giving these materials a strong future in nanomedicine applications.

Template-free electrosynthesis of crystalline germanium nanowires from solid germanium oxide in molten CaCl2–NaCl

Germanium nano-materials are attractive due to their potential application prospects in electronic, information and energy industry. Herein we report a one-step preparation of crystalline germanium nanowires (Ge-NWs) by direct electrochemical reduction of solid GeO2 in molten CaCl2–NaCl at 600°C with a current efficiency of ~86% and an energy consumptions as low as 3.26kWh (kgGe)−1. The cyclic voltammogram of the GeO2-filled cavity electrode shows that the onset electroreduction potential of GeO2 is −1.0V vs. Ag/Ag+, much more positive than the reduction potential of cations in the melt. The as-prepared Ge-NWs are of high aspect ratio, high purity and good crystallinity according to the XRD, EDX, SEM and TEM characterizations. The present approach provides a simple and short process for the production of Ge-NWs from a cost-affordable germanium precursor (GeO2). The potential applications of the obtained Ge for photodetector and infrared optical window have been also investigated by Raman and FT-IR measurements.

Synthesis and Characterization of Germanium Coordination Compounds for Production of Germanium Nanomaterials.

A series of novel germanium(II) precursors was synthesized to initiate an investigation between the precursors' structures and the morphologies of the resulting nanoparticles. The precursors were synthesized from the reaction of Ge[N(SiMe3)2]2 or [Ge(OBut)2]2 and the appropriate ligand: N,N'-dibenzylethylenediamine (H2-DBED), tert-butanol (H-OBut), 2,6-di-methyl phenol (H-DMP), 2,6-di-phenyl phenol (H-DPP), tert-butyldimethylsilanol (H-DMBS), triphenylsilanol (H-TPS), triphenylsilanethiol (H-TPST), and benzenethiol (H-PS). The products were identified as: [Ge(μc-DBED)]2 (1, μc= bridging chelating), [Ge(μ-DMP)(DMP)]2 (2), Ge(DPP)2 (3), [Ge(μ-OBut)(DMBS)]2, (4), [Ge(μ-DMBS)(DMBS)]2 (5), Ge(TPS)3(H) (6), [Ge(μ-TPST)(TPST)]2 (7), and Ge(PS)4 (8). The Ge(II) metal centers were found to adopt a pyramidal geometry for 1, 2, 4, 5, 7, a bent arrangement for 3, and a tetrahedral coordination for the Ge(IV) species 6 and 8. Using a simple solution precipitation methodology, Ge(0) nanomaterials were isolated as dots and wires for the majority of precursors. Compound 7 led to the isolation of amorphous GexSy. The nanomaterials isolated were characterized by TEM, EDS, and powder XRD. A correlation between the precursor's arrangement and final observed nanomorphology was proffered as part of the 'precursor structure affect' phenomenon.