Effect of Metal Nanoparticle Aggregate Structure on the Thermodynamics of Oxidative Dissolution
Effect of Metal Nanoparticle Aggregate Structure on the Thermodynamics of Oxidative Dissolution
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金属纳米粒子聚集结构对氧化溶解热力学的影响
DOI：
10.1021/acs.langmuir.1c00565
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发表时间：
2021
期刊：
影响因子：
3.9
通讯作者：
Zamborini, Francis P.
中科院分区：
文献类型：
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作者：
Pattadar, Dhruba K.;Nambiar, Harikrishnan N.;Allen, Stacy L.;Jasinski, Jacek B.;Zamborini, Francis P.
在这里，我们比较了由酸（低pH）聚集的15 nm直径的柠檬酸盐稳定的Au NPs与由四（羟甲基）氯化鏻（THPC）聚集的那些的电化学氧化电位。对于酸诱导的聚集，溶液变为蓝紫色，Au NPs在520 nm处的局部表面等离子体共振（LSPR）带随着较高波长（600-800 nm）处吸光度的增加而沿着降低，并且在溴化物中获得的阳极溶出伏安法（ASV）中的峰值氧化电位（Ep）具有高达200 mV的正移。对于THPC诱导的聚集体（Au/THPC摩尔比= 62.5），随着520 nm处的LSPR带的减少，溶液变为蓝色，并在700 nm处出现一个新的明显峰，但Ep不显示正位移。扫描透射电子显微镜（STEM）图像显示，酸诱导的聚集体是三维的，具有强烈融合的Au NP-Au NP接触，而THPC诱导的聚集体是线性或二维的，Au NPs之间的间距为1.1 nm。由于强的Au NP-Au NP接触，酸聚集的Au NP的表面积与体积比（SA/V）降低，这导致较低的表面自由能和较高的Ep。对于THPC聚集的Au NP，SA/V不改变，因为在它们之间保留空间并且它们的SA是完全可接近的。这些发现表明，由ASV测定的金属NP氧化稳定性对聚集体结构的细节高度敏感。
Here, we compare the electrochemical oxidation potential of 15 nm diameter citrate-stabilized Au NPs aggregated by acid (low pH) to those aggregated by tetrakis(hydroxymethyl) phosphonium chloride (THPC). For acid-induced aggregation, the solution changes to a blue-violet color, the localized surface plasmon resonance (LSPR) band of Au NPs at 520 nm decreases along with an increase in absorbance at higher wavelengths (600–800 nm), and the peak oxidation potential (Ep) in anodic stripping voltammetry (ASV) obtained in bromide has a positive shift by as large as 200 mV. For THPC-induced aggregation (Au/THPC mole ratio = 62.5), the solution changes to a blue color as the LSPR band at 520 nm decreases and a new distinct peak at 700 nm appears, but theEpdoes not exhibit a positive shift. Scanning transmission electron microscopy (STEM) images reveal that acid-induced aggregates are three-dimensional with strongly fused Au NP–Au NP contacts, while THPC-induced aggregates are linear or two-dimensional with ∼1 nm separation between Au NPs. The surface area-to-volume ratio (SA/V) decreases for acid-aggregated Au NPs due to strong Au NP–Au NP contacts, which leads to lower surface free energy and a higherEp. The SA/V does not change for THPC-aggregated Au NPs since space remains between them and their SA is fully accessible. These findings show that metal NP oxidative stability, as determined by ASV, is highly sensitive to the details of the aggregate structure.