铂催化剂是一种以金属铂为主要活性组分制成的催化剂的总称。采用铂金属网、铂黑、或把铂载于氧化铝等载体上，也可含有金属铼等助催化剂组分。主要用于氨氧化、石油烃重整、不饱和化合物氧化及加氢、气体中一氧化碳、氮氧化物的脱除等过程。是化学、石油和化工反应过程经常采用的一种催化剂。

Platinum catalyst is a general term for catalysts made of metal platinum as the main active component. It uses platinum metal mesh, platinum black, or platinum on carriers such as alumina, and may also contain metal rhenium and other co-catalyst components. It is mainly used in ammonia oxidation, petroleum hydrocarbon reforming, unsaturated compound oxidation and hydrogenation, and removal of carbon monoxide and nitrogen oxides in gas. It is a catalyst often used in chemical, petroleum and chemical reaction processes.

铂纳米催化剂表现出卓越的可逆性：催化剂稳定性和可重复使用性的飞跃

Platinum Nanocatalysts Show Remarkable Reversibility: A Leap Forward in Catalyst Stability and Reusability

在一项开创性的研究中，美国能源部布鲁克海文国家实验室和石溪大学的研究人员揭示了一种非凡的过程，即在反应条件下，二氧化铈基上的铂原子可以组装成活性纳米催化剂，然后在冷却时分解。这一发现发表在《纳米尺度》杂志上，对催化剂的稳定性和再利用具有重要意义，可能会彻底改变纳米催化领域。 In a groundbreaking study, researchers from the U.S. Department of Energy’s Brookhaven National Laboratory and Stony Brook University have unveiled a remarkable process by which platinum atoms on a cerium oxide base can assemble into active nanocatalysts under reaction conditions and then disassemble upon cooling. This discovery, published in the journal Nanoscale, has significant implications for the stability and reuse of catalysts, potentially revolutionizing the field of nanocatalysis.

组装与拆卸：活力二人组 Assembly and Disassembly: A Dynamic Duo

在反应的高温条件下（572°F 或 300°C），二氧化铈表面上的单个铂原子会聚在一起形成活性催化纳米颗粒。有趣的是，当反应结束并且系统冷却时，这些纳米颗粒会分解回单个铂原子。与人们的预期相反，这种可逆碎片化实际上可以增强催化剂的长期稳定性。 Under the high-temperature conditions of a reaction (572°F or 300°C), single platinum atoms on a cerium oxide surface come together to form active catalytic nanoparticles. Intriguingly, when the reaction ends and the system cools, these nanoparticles disassemble back into individual platinum atoms. This reversible fragmentation, contrary to what one might expect, could actually enhance the catalyst’s long-term stability. 布鲁克海文实验室化学家、石溪大学教授、这项研究的负责人阿纳托利·弗兰克尔说：“铂纳米催化剂在二氧化铈上的这种可逆碎裂可能有助于控制催化剂的长期稳定性。” “Such reversible fragmentation of a platinum nanocatalyst on cerium oxide could be potentially useful for controlling the catalyst’s long-term stability,” said Anatoly Frenkel, a chemist at Brookhaven Lab and professor at Stony Brook University who led the research.

一氧化碳的作用 The Role of Carbon Monoxide

这一过程中的关键因素是“逆水煤气变换”反应的副产品一氧化碳 (CO)。CO 分子表现出强烈的排斥相互作用，这种相互作用随着它们冷却并积聚在铂原子上而增强。这些相互作用导致 CO 分子将结合较松散的铂原子从纳米颗粒上拉开，从而将它们分散到二氧化铈载体上。韩国忠南国立大学的同事通过热力学计算证实了这一机制。 A key player in this process is carbon monoxide (CO), a byproduct of the "reverse water gas shift" reaction. CO molecules exhibit strong repulsive interactions, which increase as they cool and accumulate on the platinum atoms. These interactions cause CO molecules to pull less tightly bound platinum atoms away from the nanoparticle, dispersing them onto the cerium oxide support. This mechanism was confirmed by thermodynamic calculations performed by colleagues at Chungnam National University in Korea.

多模态成像和光谱 Multimodal Imaging and Spectroscopy

为了解开这一现象，研究人员采用了一系列先进的技术： To unravel this phenomenon, the researchers employed a suite of advanced techniques: 国家同步加速器光源二号的X射线吸收光谱提供了对原子电子状态的深入了解，揭示了铂原子、二氧化铈中的氧和一氧化碳之间的相互作用。 X-ray Absorption Spectroscopy at the National Synchrotron Light Source-II provided insights into the electronic states of the atoms, revealing interactions between platinum atoms, oxygen from cerium oxide, and carbon monoxide.

布鲁克海文实验室 SDAN 实验室的红外光谱区分了单个铂原子和纳米颗粒，展示了 CO 在反应过程中和反应后如何与它们相互作用。 Infrared Spectroscopy at Brookhaven Lab’s SDAN laboratory differentiated between single platinum atoms and nanoparticles, showing how CO interacts with each during and after the reaction.

布鲁克海文功能纳米材料中心的电子显微镜产生了纳米级图像，证实了在反应的不同阶段存在单个原子和纳米粒子。 Electron Microscopy at Brookhaven’s Center for Functional Nanomaterials produced nanoscale images confirming the presence of both single atoms and nanoparticles at different stages of the reaction.

“这些技术综合起来告诉我们，一旦反应停止，温度下降，纳米颗粒就会开始分裂成单个原子，”Frenkel 说。“每次独立测量都无法为我们提供足够的数据来了解我们正在处理的问题。” “These techniques together tell us that, once the reaction stops and the temperature drops, the nanoparticles have started to fragment into single atoms,” Frenkel said. “Each measurement independently would not have given us enough data to understand what we are dealing with.”

对催化剂设计的影响 Implications for Catalyst Design

这一发现对催化剂的设计和使用具有深远的影响。铂纳米催化剂的可逆性质可以防止纳米颗粒的不可逆融合，这是导致许多催化剂失活的常见问题。此外，组装和拆卸过程会在纳米颗粒中引入缺陷和应变，这可以通过改善反应物和催化剂之间的电子能级对齐来增强其催化性能。 The findings have far-reaching implications for the design and use of catalysts. The reversible nature of the platinum nanocatalysts could prevent the irreversible fusion of nanoparticles, a common issue that deactivates many catalysts. Additionally, the process of assembly and disassembly introduces defects and strain into the nanoparticles, which could enhance their catalytic performance by improving the alignment of electronic levels between the reactants and the catalyst. “人们试图故意设计具有这些类型缺陷的催化剂；我们的方法自然地融入了应变，”弗伦克尔解释道。 “People try to design catalysts with these types of imperfections deliberately; our method incorporates strain naturally,” Frenkel explained.

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