Solid-Phase Photochemical Growth of Composition-Variable Au-Ag Alloy Nanoparticles in AgBr Crystal
Solid-Phase Photochemical Growth of Composition-Variable Au-Ag Alloy Nanoparticles in AgBr Crystal
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DOI：
10.1021/acs.jpcc.7b04531
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发表时间：
2017-09-28
影响因子：
3.7
通讯作者：
Tada, Hiroaki
中科院分区：
文献类型：
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作者：
Naya, Shin-ichi;Hayashido, Yoshihiro;Tada, Hiroaki
银-卤化银(Ag-AgX，X=Cl，Br，I)是一种新型的可见光催化剂，可用于太阳-化学转化。提高等离子体光催化剂活性的关键是局部电场增强(LEFE)和有效利用太阳光作为能源的兼容性。银纳米粒子(NP)具有强烈的LEFE效应，而吸收峰位于可见光区的蓝边附近。另一方面，Au-NP具有与太阳光谱很好匹配的吸收，但LEFE比Ag-NP小得多。Au-x-Ag1-x合金Np的光学性质介于Ag和Au NPs之间，随成分x的不同而变化，因此，Np掺杂的Au-x-Ag1-x合金(Au-x-Ag1-x@Agx)有望成为一种很有前途的等离子体光催化剂。第一步，采用连续离子层吸附反应(SILAR)方法在介孔二氧化钛薄膜上制备了金离子掺杂的AgBrNPs。在第二步，样品在甲醇中紫外光照射(波长320 nm)，在AgBr内部得到直径接近5 nm的Au-x-Ag1-x合金颗粒，微晶尺寸接近50 nm。局域表面等离子体共振的峰值波长可以通过合金成分在500~600 nm范围内调谐。在实验和密度泛函理论计算结果的基础上，我们提出了一个合理的反应机理。
Silver-silver halides (Ag-AgX, X = Cl, Br, I) have emerged as a new type of visible-light photocatalyst for solar-to-chemical transformations. The key to improving the activity of the plasmonic photocatalyts is the compatibility of local electric field enhancement (LEFE) and effective utilization of the sunlight as the energy source. A Ag nanoparticle (NP) possesses an intense LEFE effect, while the absorption peak is situated near the blue edge of the visible region. On the other hand, the Au NP has an absorption matching well the solar spectrum, but the LEFE is much smaller than that of a Ag NP. The optical property of a Au-x-Ag1-x alloy NP varies between those of Ag and Au NPs depending on the composition x, and thus, Au-x-Ag1-x alloy NP-incorporated AgX (Au-x-Ag1-x@AgX) can be a promising plasmonic photocatalyst. At the first step, gold ion-doped AgBr NPs are formed on mesoporous TiO2 film by the successive ionic layer adsorption and reaction (SILAR) method. At the second step, UV-light irradiation (lambda > 320 nm) of the sample in methanol yields Au-x-Ag1-x alloy particles having diameter of similar to 5 nm in the interior of AgBr with crystallite size of similar to 50 nm. The peak wavelength for the localized surface plasmon resonance can be tuned in the range between 500 and 600 nm through the alloy composition. On the basis of the experimental and density functional theory calculation results, we propose a plausible reaction mechanism.