Camus Élise, Pellarin Michel, Blanchard Nicholas, Boisron Olivier, Hillenkamp Matthias, Roiban Lucian, Andreazza Pascal, Cottancin Emmanuel
Univ. Lyon 1, CNRS, iLM, UMR 5306, F- 69622 Villeurbanne, France.
Univ Lyon, INSA Lyon, UCBL, CNRS, MATEIS, UMR5510, F-69621 Villeurbanne, France.
Faraday Discuss. 2023 Jan 31;242(0):478-498. doi: 10.1039/d2fd00109h.
In this study, the atomic and chemical structure and the optical response of AB bimetallic nanoparticles (BNPs) combining gold or silver (A) with aluminium or indium (B) were investigated at various stoichiometries in order to examine if stable alloyed phases could exist and promote the emergence of localized surface plasmon resonance (LSPR) in the UV range. The structure and morphology of BNPs of a few nanometres, produced by laser vaporization, were analysed by transmission electron microscopy (TEM) and optical absorption measurements were performed on matrix-embedded BNPs. Information about the oxidation state of the BNPs can be inferred from a comparison between experimental optical spectra and Mie calculations in the dipolar approximation. The BNPs' internal structures were further investigated by additional characterization techniques. Firstly, X-ray photoelectron spectroscopy provided information about the chemical state of the constituent elements and their evolution with time. Secondly, synchrotron-based X-ray scattering techniques were performed on Ag-Al BNPs in a wide-angle configuration under grazing incidence, giving complementary information about structural and morphological heterogeneities in the BNPs. Finally, the restructuring of the partially oxidized AuAl BNPs annealed in a reducing atmosphere was also attempted by environmental TEM. The complementary techniques of characterization show that silver-based Ag-In and Ag-Al BNPs form metallic silver-rich alloyed cores surrounded by an indium or aluminium oxide shell. The initial LSPR is in the UV range for both systems, but the difference in the kinetics of oxidation between indium and aluminium involves less blue-shifted LSPR for Ag-Al BNPs. In the case of gold-based BNPs, we show evidence of ordered nanoalloys just after air exposure and the appearance of gold and indium (or aluminium) demixing during oxidation. The initial LSPR of Au-In BNPs is the one the most in the UV range among the four systems, with an LSPR peak centred at 254 nm, which may be a sign of the formation of the AuIn alloy. Nevertheless, strategies to preserve BNPs from oxidation have to be developed.
在本研究中，研究了将金或银（A）与铝或铟（B）相结合的AB双金属纳米颗粒（BNP）在各种化学计量比下的原子和化学结构以及光学响应，以检验是否能形成稳定的合金相并促进紫外范围内局域表面等离子体共振（LSPR）的出现。通过激光蒸发制备的几纳米BNP的结构和形态，用透射电子显微镜（TEM）进行了分析，并对嵌入基质的BNP进行了光吸收测量。通过在偶极近似下将实验光谱与米氏计算进行比较，可以推断出BNP的氧化态信息。通过其他表征技术进一步研究了BNP的内部结构。首先，X射线光电子能谱提供了有关组成元素化学状态及其随时间演变的信息。其次，在掠入射下以广角配置对Ag-Al BNP进行了基于同步加速器的X射线散射技术，给出了有关BNP结构和形态异质性的补充信息。最后，还尝试通过环境TEM对在还原气氛中退火的部分氧化的AuAl BNP进行重构。这些互补的表征技术表明，银基Ag-In和Ag-Al BNP形成了富含金属银的合金核，周围是氧化铟或氧化铝壳。两种体系的初始LSPR均在紫外范围内，但铟和铝氧化动力学的差异导致Ag-Al BNP的LSPR蓝移较小。对于金基BNP，我们展示了刚暴露于空气中时有序纳米合金的证据以及氧化过程中金和铟（或铝）的分离现象。Au-In BNP的初始LSPR是四个体系中最处于紫外范围内的，其LSPR峰位于254 nm处，这可能是形成AuIn合金的迹象。然而，必须开发防止BNP氧化的策略。
