本研究首度利用膠體合成法成功合成出二碲化鎢花狀形貌的奈米粒子。二碲化鎢屬於過渡金屬硫族化合物，具有Te-W-Te為單位堆疊之層狀結構，由掃描式電子顯微鏡影像得知，二碲化鎢奈米粒子具有高均勻性的粒子尺寸，粒子直徑約500~600nm;經由X光繞射分析、高解析穿透式電子顯微鏡影像及X光光電子能譜儀分析，確認合成出之奈米粒子具有可靠的純度以及良好的結晶性且同時具有2H及1T’(1T distortion)之結構，由穿透式電子顯微鏡影像顯示膠體合成之二碲化鎢奈米粒子具有豐富的少數層，其層間距為0.715 nm，與X光繞射圖譜之分析結果相符合。而由X光光電子能譜儀及能量散佈分析儀之分析可以確認鎢原子與碲原子之鍵結訊號，同時在二碲化鎢奈米粒子表面也會偵測到與氧鍵結的訊號，顯示出膠體合成之二碲化鎢奈米粒子具有長期表面穩定性的問題。進一步利用壓電響應力顯微鏡以及穿隧式原子力顯微鏡分析證實膠體合成之二碲化鎢奈米花之正、逆壓電性質。根據此一特性，對二碲化鎢奈米花進行壓電觸媒實驗分析，結果顯示30 mg之二碲化鎢奈米粒子在超音波震盪作為外加應力源之情況下可將30 ml的亞甲基藍染料(以下簡稱染料)水溶液在10秒內降解至完全透明，且具有重複再利用的優點，在第三次試驗下依舊可將染料水溶液在1分鐘內降解至剩餘10%。

We are the first group to synthesize few-layers tungsten ditelluride (WTe2) nanoflowers, which is a member of two-dimensional transition metal dichalcogenide by using colloidal synthesis technique. The crystal structure of the WTe2 nanoflowers have been confirmed by X-ray diffraction pattern (XRD), Raman, and High-resolution transmission electron microscope (HRTEM). According to the scanning electron microscope (SEM) images, the WTe2 nanoflowers contain a great number of few-layers nanopetals and possess high uniformity. HRTEM image reveals that in each WTe2 nanoflowers own a large number of few layers and have high crystallinity，which confirms that our nanoflowers display a large population of active sites. In addition, the lattice fringes between each single layer is about 0.715nm, which is slightly larger than the reported value of 0.7nm for the WTe2. The piezoresponse force microscopy (PFM) and tunneling atomic force microscopy analysis (TUNA) further indicate that the WTe2 nanoflowers exhibit impressive piezoelectric potential, which is generated from the active edge sites of WTe2 nanoflowers. By the way, piezocatalyst experiment also manifest that these WTe2 nanoflowers can successfully degrade the Methylene blue (MB) dye solution in 10 seconds with the assist of ultrasonic vibration which was served as a mechanical force to induce piezoelectric response.

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