Template-Free Preparation of Crystalline Ge Nanowire Film Electrodes via an Electrochemical Liquid–Liquid–Solid Process in Water at Ambient Pressure and Temperature for Energy Storage

Abstract

The direct electrodeposition of crystalline germanium (Ge) nanowire film electrodes from an aqueous solution of dissolved GeO(2) using discrete 'flux' nanoparticles capable of dissolving Ge(s) has been demonstrated. Electrodeposition of Ge at inert electrode substrates decorated with small (<100 nm), discrete indium (In) nanoparticles resulted in crystalline Ge nanowire films with definable nanowire diameters and densities without the need for a physical or chemical template. The Ge nanowires exhibited strong polycrystalline character as-deposited, with approximate crystallite dimensions of 20 nm and a mixed orientation of the crystallites along the length of the nanowire. Energy dispersive spectroscopic elemental mapping of individual Ge nanowires showed that the In nanoparticles remained at the base of each nanowire, indicating good electrical communication between the Ge nanowire and the underlying conductive support. As-deposited Ge nanowire films prepared on Cu supports were used without further processing as Li(+) battery anodes. Cycling studies performed at 1 C (1624 mA g(-1)) indicated the native Ge nanowire films supported stable discharge capacities at the level of 973 mA h g(-1), higher than analogous Ge nanowire film electrodes prepared through an energy-intensive vapor-liquid-solid nanowire growth process. The cumulative data show that ec-LLS is a viable method for directly preparing a functional, high-activity nanomaterials-based device component. The work presented here is a step toward the realization of simple processes that make fully functional energy conversion/storage technologies based on crystalline inorganic semiconductors entirely through benchtop, aqueous chemistry and electrochemistry without time- or energy-intensive process steps.

Влияние температуры электролита на процесс катодного осаждения нитевидных наноструктур Ge из водных растворов на частицах In и Sn

“…Таким образом, отсутствие роста на Sn и его наличие на In, а также сопоставление полученных нами экспериментальных ре-зультатов с результатами работ [12,13,15] указывают на то, что основополагающую роль для синтеза нитевидных нанокристаллов Ge из водного раствора является нали-чие частиц металла в жидком состоянии.…”

“…• C. Так, в работе [15] возможность роста нитевидных структур германия из водных растворов с использованием частиц In с размера-ми, не превышающими 100 нм (температура плавления объемного In составляет ∼ 156.6…”

“…Известно, что тем-пература плавления снижается с уменьшением размеров металлических частиц [16]. Однако в работе [15] сделано только лишь предположение о возможном расплавлении частиц металла в ходе процесса роста.…”

Recent advances in the growth of germanium nanowires: synthesis, growth dynamics and morphology control

“…Vapour and liquid-based growth of Ge nanowires consists of any method where the Ge precursor is in either vapour and liquid form and include techniques such as chemical vapour deposition (CVD) [45][46][47][48][49][50] , metal-organic chemical vapour deposition (MOCVD) 51 52 , molecular beam epitaxy [53][54][55] , template methods 56,57 and various evaporation methods such as electron beam evaporation 58,59 and thermal evaporation 60,61 . Alternatively, liquid/solution (see figure 1) 14,52,[62][63][64][65][66][67] and SCF [68][69][70][71][72] based methods involve the introduction of precursors in liquid and supercritical media respectively. The key mechanism involved in most of these processes is analogous to the VLS mechanism first proposed by…”

Ge Nanoparticles Encapsulated in Nitrogen-Doped Reduced Graphene Oxide as an Advanced Anode Material for Lithium-Ion Batteries

“…[26][27][28][29][30][31] Previously studies have demonstrated that decreasing the Ge particle size into the nanometer range could alleviate the stress produced during Li uptake and release processes and suppress the tendency of the nanostructure to fracture. [32][33][34][35] Moreover, the nanostructure can facilitate the diffusion of Li ion, resulting in high rate capability. [36][37][38][39] However, the cycling performance remains unsatisfactory because the Ge nanoparticles aggregate during cycling.…”