發(fā)布時(shí)間：2018-11-10 16:47

【摘要】：采用原位液體池透射電鏡技術(shù),在掃描透射電子顯微鏡(STEM)中,實(shí)時(shí)觀察溶液中金屬鈀(Pd)在金(Au)納米顆粒及團(tuán)簇周?chē)漠愘|(zhì)沉積過(guò)程。通過(guò)對(duì)該動(dòng)態(tài)過(guò)程的定量分析,結(jié)合高分辨透射電子顯微鏡(HRTEM)對(duì)樣品進(jìn)行形貌與結(jié)構(gòu)表征,研究異質(zhì)沉積的機(jī)理。結(jié)果表明,電子束輻照下Au-Pd異質(zhì)結(jié)構(gòu)納米顆粒的形成存在兩種主要機(jī)制:第一種機(jī)制中,Pd在Au納米顆粒表面的生長(zhǎng)是以島狀沉積開(kāi)始,隨著時(shí)間推移,出現(xiàn)Pd島的結(jié)構(gòu)弛豫和沿著Au顆粒表面的遷移擴(kuò)展。伴隨Pd的不斷沉積和弛豫,Au-Pd復(fù)合顆粒的外接圓直徑表現(xiàn)為震蕩生長(zhǎng),而Au表面的Pd覆蓋率顯示出隨時(shí)間單調(diào)增加的趨勢(shì)。第二種機(jī)制中,由于Pd單體在Au納米顆粒上的沉積位點(diǎn)有限,使部分被還原的Pd在Au顆粒以外區(qū)域進(jìn)行同質(zhì)形核與生長(zhǎng)形成Pd團(tuán)簇,之后再與Au顆粒上的Pd島合并。進(jìn)一步的結(jié)果分析顯示,Au顆粒外圍的Pd沉積體為多晶結(jié)構(gòu),由隨機(jī)取向的Pd納米晶粒構(gòu)成。
[Abstract]:In situ liquid cell transmission electron microscopy (TEM) technique was used to observe the heterogeneous deposition of palladium (Pd) in solution around gold (Au) nanoparticles and clusters by scanning transmission electron microscopy (STEM). The mechanism of heterogeneous deposition was studied by quantitative analysis of the dynamic process and characterization of the morphology and structure of the samples by high resolution transmission electron microscope (HRTEM). The results show that there are two main mechanisms for the formation of Au-Pd heterostructure nanoparticles under electron beam irradiation. In the first mechanism, the growth of Pd on the surface of Au nanoparticles begins with island deposition. Structural relaxation of Pd island and migration and propagation along the surface of Au particles occur. With the continuous deposition and relaxation of Pd, the diameter of the outer circle of Au-Pd composite particles appears to be oscillating, while the Pd coverage of Au surface shows a monotone increasing trend with time. In the second mechanism, due to the limited deposition sites of Pd monomers on Au nanoparticles, partial reduced Pd nucleates and grows into Pd clusters outside Au particles, and then merges with Pd islands on Au particles. The further analysis shows that the Pd deposition in the periphery of Au particles is polycrystalline and consists of randomly oriented Pd nanocrystals.
【作者單位】： 華東理工大學(xué)材料科學(xué)與工程學(xué)院超細(xì)材料制備與應(yīng)用教育部重點(diǎn)實(shí)驗(yàn)室上海市先進(jìn)聚合物材料重點(diǎn)實(shí)驗(yàn)室;浙江大學(xué)材料科學(xué)與工程學(xué)院硅材料國(guó)家重點(diǎn)實(shí)驗(yàn)室;中國(guó)科學(xué)院上海微系統(tǒng)與信息技術(shù)研究所信息功能材料國(guó)家重點(diǎn)實(shí)驗(yàn)室;
【基金】：上海市重點(diǎn)學(xué)科項(xiàng)目(B502) 上海市重點(diǎn)實(shí)驗(yàn)室項(xiàng)目(08DZ2230500) 上海市科學(xué)技術(shù)委員會(huì)項(xiàng)目(11nm0507000) 信息功能材料國(guó)家重點(diǎn)實(shí)驗(yàn)室開(kāi)放課題(SKL201306) 國(guó)家自然科學(xué)基金(51222202)資助~~
【分類(lèi)號(hào)】：O614.823;O647

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