Guda Alexander A, Bugaev Aram L, Kopelent Rene, Braglia Luca, Soldatov Alexander V, Nachtegaal Maarten, Safonova Olga V, Smolentsev Grigory
The Smart Materials Research Center, Southern Federal University, Sladkova 174/28, Rostov-on-Don 344090, Russian Federation.
Paul Scherer Institute, Villigen 5232, Switzerland.
J Synchrotron Radiat. 2018 Jul 1;25(Pt 4):989-997. doi: 10.1107/S1600577518005325. Epub 2018 May 30.
A setup for fluorescence-detected X-ray absorption spectroscopy (XAS) with sub-second time resolution has been developed. This technique allows chemical speciation of low-concentrated materials embedded in highly absorbing matrices, which cannot be studied using transmission XAS. Using this setup, the reactivity of 1.5 wt% Pt/CeO catalyst was studied with 100 ms resolution during periodic cycling in CO- and oxygen-containing atmospheres in a plug-flow reactor. Measurements were performed at the Pt L- and Ce L-edges. The reactivity of platinum and cerium demonstrated a strong correlation. The oxidation of the catalyst starts on the ceria support helping the oxidation of platinum nanoparticles. The new time-resolved XAS setup can be applied to various systems, capable of reproducible cycling between different states triggered by gas atmosphere, light, temperature, etc. It opens up new perspectives for mechanistic studies on automotive catalysts, selective oxidation catalysts and photocatalysts.
已开发出一种具有亚秒级时间分辨率的用于荧光检测X射线吸收光谱（XAS）的装置。该技术能够对嵌入高吸收性基质中的低浓度材料进行化学形态分析，而这是使用透射XAS无法研究的。利用该装置，在活塞流反应器中，于含CO和氧气的气氛中进行周期性循环时，以100毫秒的分辨率研究了1.5 wt% Pt/CeO催化剂的反应活性。在Pt L边和Ce L边进行了测量。铂和铈的反应活性显示出很强的相关性。催化剂的氧化始于氧化铈载体，有助于铂纳米颗粒的氧化。这种新的时间分辨XAS装置可应用于各种系统，能够在由气体气氛、光、温度等触发的不同状态之间进行可重复的循环。它为汽车催化剂、选择性氧化催化剂和光催化剂的机理研究开辟了新的视角。
