报告人：Günther Rupprechter教授（维也纳工业大学）

报告题目：Operando spectroscopy and microscopy of applied and model catalysts

报告时间：2024年7月27日上午9:30

报告地点：苏州大学独墅湖校区909 B厅

报告摘要

Operando spectroscopy of catalytic reactions has been very successful in mechanistic studies.¹ However, as spectroscopy typically examines large areas/volumes, this averaging “smoothens out” local variations that may be critical to understand how a reaction proceeds. Dynamics in catalyst structure, composition and adsorbate coverage may also go unnoticed by averaged spectral data. A way overcoming these limitations is to use correlative surface microsopy to directly “watch” ongoing catalytic reactions, i.e. to apply several microscopic and spectro-microscopic techniques to the same catalysts locations under identical reaction conditions.² Most of the methods herein not only image catalyst structure or composition, but also the adsorbed reactants, so that active and inactive states can be discerned (kinetics by imaging), active regions identified and mechanisms elucidated.³

Examples of real-time in situ imaging of H₂ oxidation include meso-scale polycrystalline Rh surfaces and Rh nanotips (as small as 30 nm, enabling single particle catalysis). For planar catalysts, UV- and X-ray photoemission electron microscopy (UV- and X-PEEM), low energy electron microscopy (LEEM) and scanning photoelectron microscopy (SPEM) were used with resolution up to 3 nm. For nanotips, field emission microscopy (FEM) and field ion microscopy (FIM) were applied with up to atomic resolution.

The direct, real-time and locally-resolved observation of H₂ oxidation on Rh-based catalysts revealed:

(i) the transition from inactive to active states via catalytic ignition and spreading of chemical waves,⁴

(ii) the mechanism of oscillatory H₂ oxidation involving subsurface oxygen,⁴

(iii) how particle size, support and surface composition (decoration, SMSI) affect the local activity,⁵

(iv) whether different facets on a single Rh nanoparticle communicate via hydrogen diffusion or not (coupled monofrequential vs. (uncloupled) multifrequential oscillations),⁶

(v) detecting active sites on a single particle via imaging water molecules,⁶

(vi) that chaos even exists at the nanoscale,⁷ and

(vii) how La modifies the reaction dynamics on a Rh nanotip.⁸

Microkinetic modelling and density functional theory (DFT) rationalized the experimental observations. The novel nanoscale insights in the dynamics of reactants and surfaces, including the identification of active regions, may stimulate new ways of catalyst design and operation.

References:

[1]   G. Rupprechter, Small 2021, 2004289.

[2]   J. Zeininger et al., ACS Catalysis 12 (2022) 11974.

[3]   Y. Suchorski, G. Rupprechter, Surface Science 643 (2016) 52.

[4]   P. Winkler et al., Nature Communications 12 (2021) 69 and 6517.

[5]   P. Winkler et al., ACS Catalysis 13 (2023) 7650.

[6]   Y. Suchorski, G. Rupprechter et al., Science 372 (2021) 1314.

[7]   M Raab et al., Nature Communications 14 (2023) 282.

[8]   M Raab et al., Nature Communications 14 (2023) 7186.

个人简介 ：

Günther Rupprechter isProfessor of Surface and Interface Chemistry at TU Wien (Vienna, Austria). He has been Renowned Overseas Professor of Shanghai University of Engineering Science and Guest Professor at Kasetsart University Bangkok.Prof. Rupprechter is Director of Research of the new Austrian Cluster of Excellence “Materials for Energy Conversion and Storage (MECS)” of the Austrian Science Fund (FWF), including 5 Austrian universities/institutions. He is member of the Austrian Academy of Sciences, Fellow of the European Academy of Sciences, Vice-Chair of the Austrian Catalysis Society and Editorial Board Member of “Catalysis Letters” and “Topics in Catalysis”. Research interests of Günther Rupprechter are in heterogeneous catalysis and nanomaterials, particularly in situ (operando) spectroscopy/microscopy of model and technological catalysts, applied to studies of the mechanisms and kinetics of processes relevant for energy and environment: hydrogen as clean fuel, methane reforming, CO₂ and olefin hydrogenation, automotive catalysis, sensing and waste remediation.

联系人：何乐 教授