Controllable Lattice Expansion of Monodisperse Face-Centered Cubic Pd–Ag Nanoparticles for C1 and C2 Alcohol Oxidation: The Role of Core–Sheath Lattice Mismatch,ACS Sustainable Chemistry & Engineering

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Controllable Lattice Expansion of Monodisperse Face-Centered Cubic Pd–Ag Nanoparticles for C1 and C2 Alcohol Oxidation: The Role of Core–Sheath Lattice Mismatch
ACS Sustainable Chemistry & Engineering ( IF 7.1 ) Pub Date : 2022-05-12 , DOI: 10.1021/acssuschemeng.2c01592
Xianzhuo Lao ₁ , Tong Sun ₁ , Xingxue Zhang ₁ , Mingyuan Pang ₁ , Aiping Fu ₂ , Peizhi Guo ₁

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Direct alcohol fuel cells are considered as promising and sustainable power sources to address global climate change as well as energy and environmental problems. However, designing efficient catalysts for the oxidation of alcohol molecules remains challenging. This study reports the synthesis of monodisperse PdAg nanoparticles (NPs) with face-centered cubic structures with controllable alloying degrees and particle diameters for improving oxidation of ethanol and methanol. Interestingly, the lattice enlargement of the silver-rich core leads to the lattice expansion of the palladium-rich sheath. The lattice expansion of the interface of the NPs leads to the upshifting of the d-band center of Pd toward the Fermi level followed by the stronger binding of a small molecule. The PdAg NPs exhibit “volcano-type” behavior, where the maximum electrocatalytic activity is governed by the balance of the adsorption energies of OH* (reactive intermediates) and CO* (blocking species). The Pd₅Ag₁ NPs exhibit electrocatalytic activities of 2402 and 1541 mA mg_Pd^–1 for ethanol oxidation reaction and methanol oxidation reaction in alkaline solution, respectively, about four and three times those of the commercial Pd/C catalysts. The enhanced mass activities of the catalysts can be further analyzed by density functional theory calculations, indicating that the lattice expansion after including silver would lead to the upshifting of the d-band center followed by the strengthened OH* binding. This work discloses a promising way to build novel nanocatalysts with controllable alloying degrees as efficient fuel cell catalysts.

中文翻译：

用于 C1 和 C2 醇氧化的单分散面心立方 Pd-Ag 纳米粒子的可控晶格扩展：核-鞘晶格失配的作用

直接酒精燃料电池被认为是解决全球气候变化以及能源和环境问题的有前途和可持续的能源。然而，设计用于醇分子氧化的有效催化剂仍然具有挑战性。本研究报道了具有可控合金度和粒径的面心立方结构的单分散 PdAg 纳米粒子 (NPs) 的合成，用于改善乙醇和甲醇的氧化。有趣的是，富银核的晶格扩大导致富钯鞘的晶格膨胀。NPs界面的晶格扩展导致Pd的d带中心向费米能级上移，随后小分子的结合力更强。PdAg NPs 表现出“火山型”行为，其中最大电催化活性取决于 OH*（反应性中间体）和 CO*（阻断物质）的吸附能平衡。钯₅ Ag ₁ NPs 在碱性溶液中对乙醇氧化反应和甲醇氧化反应的电催化活性分别为 2402 和 1541 mA mg _Pd^-1，约为商业 Pd/C 催化剂的 4 倍和 3 倍。可以通过密度泛函理论计算进一步分析催化剂质量活性的增强，表明加入银后的晶格膨胀会导致 d 带中心的上移，从而增强 OH* 结合。这项工作揭示了一种有前途的方法来构建具有可控合金化度的新型纳米催化剂作为高效的燃料电池催化剂。

更新日期：2022-05-12

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