鉑催化劑是一種以金屬鉑為主要活性組分制成的催化劑的總稱。采用鉑金屬網、鉑黑、或把鉑載于氧化鋁等載體上，也可含有金屬錸等助催化劑組分。主要用于氨氧化、石油烴重整、不飽和化合物氧化及加氫、氣體中一氧化碳、氮氧化物的脫除等過程。是化學、石油和化工反應過程經常采用的一種催化劑。

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.

鉑納米催化劑表現出卓越的可逆性：催化劑穩定性和可重復使用性的飛躍

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

在一項開創性的研究中，美國能源部布魯克海文國家實驗室和石溪大學的研究人員揭示了一種非凡的過程，即在反應條件下，二氧化鈰基上的鉑原子可以組裝成活性納米催化劑，然后在冷卻時分解。這一發現發表在《納米尺度》雜志上，對催化劑的穩定性和再利用具有重要意義，可能會徹底改變納米催化領域。 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.

組裝與拆卸：活力二人組 Assembly and Disassembly: A Dynamic Duo

在反應的高溫條件下（572°F 或 300°C），二氧化鈰表面上的單個鉑原子會聚在一起形成活性催化納米顆粒。有趣的是，當反應結束并且系統冷卻時，這些納米顆粒會分解回單個鉑原子。與人們的預期相反，這種可逆碎片化實際上可以增強催化劑的長期穩定性。 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. 布魯克海文實驗室化學家、石溪大學教授、這項研究的負責人阿納托利·弗蘭克爾說：“鉑納米催化劑在二氧化鈰上的這種可逆碎裂可能有助于控制催化劑的長期穩定性。” “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

這一過程中的關鍵因素是“逆水煤氣變換”反應的副產品一氧化碳 (CO)。CO 分子表現出強烈的排斥相互作用，這種相互作用隨著它們冷卻并積聚在鉑原子上而增強。這些相互作用導致 CO 分子將結合較松散的鉑原子從納米顆粒上拉開，從而將它們分散到二氧化鈰載體上。韓國忠南國立大學的同事通過熱力學計算證實了這一機制。 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.

多模態成像和光譜 Multimodal Imaging and Spectroscopy

為了解開這一現象，研究人員采用了一系列先進的技術： To unravel this phenomenon, the researchers employed a suite of advanced techniques: 國家同步加速器光源二號的X射線吸收光譜提供了對原子電子狀態的深入了解，揭示了鉑原子、二氧化鈰中的氧和一氧化碳之間的相互作用。 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.

布魯克海文實驗室 SDAN 實驗室的紅外光譜區分了單個鉑原子和納米顆粒，展示了 CO 在反應過程中和反應后如何與它們相互作用。 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.

布魯克海文功能納米材料中心的電子顯微鏡產生了納米級圖像，證實了在反應的不同階段存在單個原子和納米粒子。 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.

“這些技術綜合起來告訴我們，一旦反應停止，溫度下降，納米顆粒就會開始分裂成單個原子，”Frenkel 說。“每次獨立測量都無法為我們提供足夠的數據來了解我們正在處理的問題。” “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.”

對催化劑設計的影響 Implications for Catalyst Design

這一發現對催化劑的設計和使用具有深遠的影響。鉑納米催化劑的可逆性質可以防止納米顆粒的不可逆融合，這是導致許多催化劑失活的常見問題。此外，組裝和拆卸過程會在納米顆粒中引入缺陷和應變，這可以通過改善反應物和催化劑之間的電子能級對齊來增強其催化性能。 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. “人們試圖故意設計具有這些類型缺陷的催化劑；我們的方法自然地融入了應變，”弗倫克爾解釋道。 “People try to design catalysts with these types of imperfections deliberately; our method incorporates strain naturally,” Frenkel explained.

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