Abstract A novel route to prepare monodispersed 1–2 nm gold nanoparticles (NPs), based on the use of extremely small SiO2 NPs (2–4 nm) as a support and increasing their metal-support interaction with surface modifier oxides is presented. The influence of modifier (La, Ce and Fe oxides) and modification method (impregnation (i) or direct synthesis (s)) on the formation of ultra-small Au NPs and their structural and electronic properties was studied. The samples were characterized by N2 adsorption (BET), FTIR of adsorbed CO, XRD and HR-TEM methods, and tested for the catalytic selective oxidation of 1-octanol. Preparation of monodispersed Au NPs with 1 nm diameter was successfully achieved for all the modified samples studied, with exception of Au/Ce/SiO2-i, where CeO2 was not homogeneously distributed. The Au NPs have high degree of monodispersity and are stable when treated in H2 up to 300 °C. Formation of these Au NPs depended on the strong interactions between the cationic gold complex precursor and the surface of modified SiO2 NPs. Modifiers changed electronic properties of supported gold; favoring the formation and stabilization of Auδ+ states, which are probable gold active sites of selective liquid-phase oxidation of alcohols in redox catalytic processes. 1-octanol oxidation was used as a model reaction for oxidation of fatty alcohols obtained during biomass transformation. The best performance for 1-octanol oxidation was found for gold nanoparticles supported on the ultra-small SiO2 modified cerium oxide by impregnation method. The relative order of activity was: AuCeSiO2-i > AuFeSiO2-i ≫ AuLaSiO2-i ≈ AuLaSiO2-s > AuSiO2 > AuFeSiO2-s≫ AuCeSiO2-s. The obtained results open the possibility of further development of high-performance catalysts for conversion of secondary products of biomass processing into valuable chemicals.

中文翻译：

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在 SiO2 载体上合成超小金纳米粒子的新途径

摘要提出了一种制备单分散 1-2 nm 金纳米粒子 (NPs) 的新途径，基于使用极小的 SiO2 NPs (2-4 nm) 作为载体并增加它们与表面改性剂氧化物的金属-载体相互作用。研究了改性剂（La、Ce 和 Fe 氧化物）和改性方法（浸渍 (i) 或直接合成 (s)）对超小金纳米粒子的形成及其结构和电子特性的影响。样品通过 N2 吸附（BET）、吸附 CO 的 FTIR、XRD 和 HR-TEM 方法进行表征，并测试了 1-辛醇的催化选择性氧化。除了 Au/Ce/SiO2-i 外，CeO2 分布不均匀，所有研究的改性样品均成功制备了直径为 1 nm 的单分散 Au NP。Au NPs 具有高度的单分散性，并且在 H2 中处理至 300 °C 时是稳定的。这些 Au NPs 的形成取决于阳离子金络合物前体与改性 SiO2 NPs 表面之间的强相互作用。改性剂改变了支撑金的电子特性；有利于 Auδ+ 状态的形成和稳定，这是氧化还原催化过程中醇选择性液相氧化的可能金活性位点。1-辛醇氧化用作生物质转化过程中获得的脂肪醇氧化的模型反应。通过浸渍法，发现负载在超小 SiO2 改性氧化铈上的金纳米粒子的 1-辛醇氧化性能最佳。活性的相对顺序是：AuCeSiO2-i > AuFeSiO2-i ≫ AuLaSiO2-i ≈ AuLaSiO2-s > AuSiO2 > AuFeSiO2-s≫ AuCeSiO2-s。所获得的结果为进一步开发用于将生物质加工的副产品转化为有价值的化学品的高性能催化剂提供了可能性。