The synthesis of size and shape controlled Au/Ag/Pd alloy nanoparticles (NPs) and their self-supported assembly into monolithic aerogels for electro-oxidation of ethanol is reported. Two distinct morphologies of ultrasmall (3–5 nm) Au/Ag/Pd alloy NPs were produced via stepwise galvanic replacement of thiol-coated Ag NPs. The resultant nanoalloys were self-assembled into large, free-standing, aerogel superstructures that exhibit direct NP connectivity, high surface area (269 ± 18.1–76 ± 6.4 m²/g) and mesoporosity (2–50 nm), and high electrocatalytic activity via controlled oxidation of the surfactant ligands. The gelation kinetics have been tuned by varying the oxidant/surfactant molar ratio that governs the acidity of sol–gel reaction and consequently the extent of Ag dealloying with in situ generated HNO₃. As-synthesized Au/Ag/Pd aerogels exhibit polymeric or colloidal gel morphology that can be manipulated by varying the shape and composition of precursor NPs. The electrocatalytic activity of ternary alloy aerogels for oxidation of ethanol was investigated using cyclic voltammetry and chronoamperometry. The monolithic aerogels exhibit high catalytic activity and durability, which is ∼20–30 times greater than those of the discrete Au/Ag/Pd alloy NPs. The polymeric morphology of high Pd-containing alloy aerogels resulted in ∼1 order of magnitude higher current density and mass activity in comparison to low Pd-containing colloidal aerogels. The synergistic effect of trimetallic alloy mitigates the catalyst poisoning effects and increases the stability and durability while the self-supported superstructure with direct NP connectivity, high surface area, and mesoporosity offers a facile conduit for both molecular and electron transport, enabling Au/Ag/Pd aerogel as a high-efficiency electrocatalyst.

中文翻译：

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Au / Ag / Pd纳米合金的形状控制合成及其氧化诱导的自组装成电催化活性气凝胶整体结构

报道了尺寸和形状可控的Au / Ag / Pd合金纳米粒子（NPs）的合成及其自支撑组装为用于乙醇电氧化的整体式气凝胶。通过逐步电置换硫醇包覆的Ag NP可以产生两种不同的超小（3-5 nm）Au / Ag / Pd合金NPs形态。所得的纳米合金可自组装成大型的，独立的气凝胶上层结构，这些结构具有直接的NP连接性，高表面积（269±18.1–76±6.4 m ² / g）和介孔率（2–50 nm），以及高电催化性通过控制表面活性剂配体的氧化产生活性。通过改变控制溶胶-凝胶反应酸度的氧化剂/表面活性剂的摩尔比，从而改变Ag的凝胶动力学，从而改变了Ag与原位生成的HNO的脱合金程度₃。合成后的Au / Ag / Pd气凝胶表现出聚合物或胶体凝胶形态，可以通过改变前体NP的形状和组成来控制。使用循环伏安法和计时电流法研究了三元合金气凝胶对乙醇氧化的电催化活性。整体式气凝胶具有很高的催化活性和耐用性，是离散的Au / Ag / Pd合金NP的约20–30倍。与低含钯胶态气凝胶相比，高含钯合金气凝胶的聚合物形态导致电流密度和质量活性提高约1个数量级。三金属合金的协同作用减轻了催化剂中毒的影响，并提高了稳定性和耐久性，而具有直接NP连接性的自支撑上部结构，