Roger M, Artiglia L, Boucly A, Buttignol F, Agote-Arán M, van Bokhoven J A, Kröcher O, Ferri D
Paul Scherrer Institut Forschungsstrasse 111, CH-5232 Villigen PSI Switzerland
École Polytechnique Fédérale de Lausanne (EPFL), Institute for Chemical Sciences and Engineering CH-1015 Lausanne Switzerland.
Chem Sci. 2023 May 30;14(27):7482-7491. doi: 10.1039/d3sc01274c. eCollection 2023 Jul 12.
Ambient pressure X-ray photoelectron spectroscopy (APXPS) is a powerful tool to characterize the surface structure of heterogeneous catalysts . In order to improve the time resolution and the signal-to-noise (S/N) ratio of photoemission spectra, we collected consecutive APXP spectra during the periodic perturbation of a powder Pd/AlO catalyst away from its equilibrium state according to the modulated excitation approach (ME). Averaging of the spectra along the alternate pulses of O and CO improved the S/N ratio demonstrating that the time resolution of the measurement can be limited solely to the acquisition time of one spectrum. Through phase sensitive analysis of the averaged time-resolved spectra, the formation/consumption dynamics of three oxidic species, two metal species, adsorbed CO on Pd as well as Pd ( > 2) was followed along the gas switches. Pd and 2-fold surface PdO species were recognised as most reactive to the gas switches. Our approach demonstrates that phase sensitive detection of time-resolved XPS data allows following the dynamics of reactive species at the solid-gas interface under different reaction environments with unprecedented precision.
环境压力X射线光电子能谱（APXPS）是表征多相催化剂表面结构的有力工具。为了提高光发射光谱的时间分辨率和信噪比（S/N），我们根据调制激发方法（ME），在粉末Pd/AlO催化剂远离其平衡态的周期性扰动过程中收集连续的APXP光谱。沿着O和CO的交替脉冲对光谱进行平均提高了信噪比，这表明测量的时间分辨率可以仅限制在一个光谱的采集时间。通过对平均时间分辨光谱的相敏分析，跟踪了三种氧化态物种、两种金属物种、吸附在Pd上的CO以及Pd（>2）在气体切换过程中的形成/消耗动力学。Pd和二倍表面PdO物种被认为对气体切换最具反应性。我们的方法表明，对时间分辨XPS数据进行相敏检测，可以以前所未有的精度跟踪不同反应环境下固-气界面反应物种的动力学。
