超細鉍奈米線的合成與機制探討

本篇研究是在溶液相系統中製備直徑約為2~4nm之超細鉍奈米線(Ultrathin Bi NWs)，並探討其生長機制。由高溫的油胺(oleylamine, OLA)作為溶劑並與前驅物2-乙基己酸鉍(Bismuth 2-ethylhexanoate) 形成高分子鏈(polymer strands)，在反應抑制劑─共聚高分子(PVP/HDE)的存在下，OLA將Bi3+ in situ還原成Bi0而合成出超細鉍奈米線。從X光粉末繞射圖譜(XRD)可判定超細鉍奈米線結構為rhomb-centered結構，而從高解析穿透式電子顯微鏡(HRTEM)可得知超細鉍奈米線沿[012]方向生長，且常聚集成束狀微結構。因鉍熔點(塊材時約為271℃)低，超細鉍奈米線在電子束照射下，會於短時間內熔化為液珠，再結晶形成多晶結構。此研究也進行多組實驗比較不同變因對合成超細鉍奈米線的影響，包含熱溶劑注射法與升溫法的差別、不同反應溫度、不同共聚高分子用量、不同界面活性劑、不同還原劑之影響，再放大實驗條件確定其工業合成的可能性。鉍奈米線也應用於鋰離子電池(LIBs)做充放電測試，其充放電速率越快，電容越低，且在50次循環充放電測試後，可觀察到電容損失的現象。

關鍵字

鉍；奈米線；合成；鋰離子電池

並列摘要

In this study, ultrathin bismuth nanowires(Bi UNWs) with an diameter of 2~4nm were synthesized in solution-phase system, and the mechanism was discussed. Oleylamine(OLA) played the role as solvent and formed polymer strands with the precursor of Bi (Bismuth 2-ethylhexanoate), then OLA reduced Bi3+ in situ to Bi0 with the existence of copolymer(PVP/HDE) as reaction inhibitor obtaining Bi UNWs. X-ray diffraction data showed that Bi UNWs are crystalline with rhomb-centered structure, and high-resolution transmission electron microscopy studies revealed that Bi UNWs grew along the [012] direction and frequently aggregated into bundle-like mesostructure, which is in accordance with X-ray diffraction data. Due to low melting point of Bi, Bi UNWs melted under electron beam irradiation, leading to the formation of small liquid droplets during TEM examination, and then re-crystallized to a polycrystalline nanowire. The experimental parameters, including method of mixing reagents, reaction temperature, amount of copolymer applied, surfactant, and reducing agent, were tuned to study their effects on the synthesis of Bi UNWs. Large scale synthetic experiment was carried out to evaluate the possibility of Bi UNWs for industrial scale production. Finally, Bi UNWs were also applied as the anode material for lithium-ion batteries. The higher the charge/discharge rate, the lower the capacity. Also, capacity fade is observed after a cycle life of 50 cycles.

並列關鍵字

Bismuth ； Nanowires ； Synthesis ； Lithium-ion batteries(LIBs)

參考文獻

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超細鉍奈米線的合成與機制探討

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