Vibrational Disorder Effects on Temperature-Resolved X-Ray Absorption Signatures of Metal Catalysts: From Single-Atoms to Clusters and Nanoparticles
Year: 2026
Type: article
Abstract: High Resolution Image Download MS PowerPoint Slide Revealing dynamic local-structure changes of (sub)nanometric metal species under operating conditions is essential. In heterogeneous catalysis, this insight enables the rationalization of operation and optimization of catalyst efficiency and stability. Extended X-ray absorption fine structure (EXAFS) provides element-specific access to metal–metal coordination numbers, interatomic distances, and local disorder, which is pivotal when active motifs lack long-range order. Yet, accurate determination of structural parameters from EXAFS signatures is often complicated by the convolution of static heterogeneity and thermal vibration effects, encoded in the Debye–Waller factor: σ 2 = σ dynamic 2 ( T ) + σ static 2 . This coupling, especially at elevated temperatures typical of in situ and operando studies, obscures genuine structural changes. Here we present a temperature-resolved EXAFS study geared toward deconvoluting σ dynamic 2 ( T ) in three supported Ag catalysts spanning different σ static 2 levels and metal aggregation states: Al 2 O 3 -supported Ag nanocrystals, few-atom Ag clusters confined to a zeotype host, and single-atom Ag dispersed on WO x /Al 2 O 3 . Over 298–723 K, representative of catalyst activation and deployment conditions, we observe a nuclearity-dependent vibrational stiffness: Ag–Ag bonds in nanoparticles show strong thermal disorder, whereas Ag–O bonds in single-atoms and confined clusters remain comparatively rigid, limiting dynamic fluxionality. While a classical formalism, such as the correlated Einstein model, adequately captures nanocrystal dynamics, it fails for few- and single-atom motifs. Therefore, a direct parametrization of σ 2 ( T ) is proposed, better capturing vibrational disorder in low-nuclearity metal catalysts. The results provide guidance for decoupling thermal and static contributions in temperature-resolved EXAFS studies, enabling a more reliable structural analysis of (sub)nanometric metal species under operando conditions.
Source: ACS Nano
Language: English
Subfield: Radiation
Field: Physics and Astronomy
Domain: Physical Sciences
Open Access status: hybrid
Estimated APC paid: $4,500
Awards: G1175115578, G121809054, G1482201912, G1622782223, G1855990336, G2064873908, G210041235, G2262748287, G2309174360, G2601397997, G2660406951, G279363373, G30027904, G3005324705, G300979063, G3325152418, G34346518, G3480869486, G3518538256, G3546882995, G3681454997, G4042783231, G410571670, G425668148, G430777504, G4442677895, G451917667, G4526231891, G5046955865, G5080475149, G5177266462, G5195188938, G5417250019, G5421974903, G5539308778, G5744226816, G5967599077, G677611228, G69051668, G7016589888, G7084143925, G726759913, G7420629364, G8460294086, G8589050819, G8920660035, G897484643, G929308097, G99296377
OpenAlex ID: W7156011264