Aqueous germanate ion solution promoted synthesis of worm-like crystallized Ge nanostructures under ambient conditions

Abstract

This work demonstrates that it is possible to synthesize crystallized Ge nanostructures directly in an aqueous medium under ambient conditions by using widely available GeO2 (in the form of germanate ions) as a precursor. The reaction of germanate ions with NaBH4 in an aqueous medium resulted in highly hydrogenated Ge that could be transformed into crystallized Ge after an air-drying treatment. The NaBH4/GeO2 molar ratio, reaction time and drying temperature were optimized for the synthesis of crystallized Ge products. Furthermore, the reaction time has an influence on the size and shape of the final crystallized Ge products. A reaction time of 12 h could result in crystallized Ge powder samples that contain ultra-small (5-20 nm) particles and larger (50-100 nm) particles. By controlling the reaction time to 24 h, a Ge powder product consisting of worm-like crystallized Ge nanostructures with diameters of 10-80 nm and lengths up to 1000 nm was obtained. The possible reaction and growth mechanisms involved in this method were investigated. This new synthetic route may be a good candidate for synthesizing a wide variety of crystallized Ge nanomaterials and devices due to its low cost, low safety risk, facileness, high yield (above 70% and in gram scale) and convenience for adding other chemicals (i.e. dopants or morphology modifying agents) into the reaction system.

Facile Synthesis of Ge@C Core–Shell Nanocomposites for High‐Performance Lithium Storage in Lithium‐Ion Batteries

“…The Ge@C core–shell nanocomposites were prepared by using a facile solution route 19. In a typical synthesis, GeO 2 (200 mg, 99.99 %, Sigma–Aldrich) was dissolved in an aqueous solution of NaOH (0.05 M , 98 %, Sigma–Aldrich).…”

Group IV Nanoparticles: Synthesis, Properties, and Biological Applications

“…The reaction of germanium diiodide with LiAlH 4 produces Ge nanocrystals with an average diameter of 3–11 nm depending on the precursor concentration 228. The reaction between GeO 2 and NaBH 4 in an aqueous medium results in 5–20 nm diameter Ge nanoparticles 229. Ultrasonic solution reduction of GeCl 4 by metal hydride and alkaline produces 3–10 nm Ge nanocrystals230 and borohydride reduction of GeCl 4 at room temperature yields 5 nm Ge nanocrystals that emit light at 352 nm 231…”

Reduced GeO2 Nanoparticles: Electronic Structure of a Nominal GeOx Complex and Its Stability under H2 Annealing

“…GeO x contains a mixture of Ge, GeO x , and GeO 2 , and in an oxidizing (or reducing) environment, these three components can transform from one species to another 19 20 21 . In fact, GeO x has been deliberately synthesized and served either as the precursor for making Ge nanocrystals and/or GeO 2 nanostructures for the purpose of fabricating electronic and optical devices 22 23 24 . Although there have been relatively large amount of early studies done on Ge nanocrystal embedded GeO x or SiO x thin films for the purpose of electronic devices fabrication, few reports are available on the structure characterization of the free-standing Ge/GeO x /GeO 2 nanocomposite in terms of battery applications.…”