Kinetics of H2 Adsorption at the Metal-Support Interface of Au/TiO2 Catalysts Probed by Broad Background IR Absorbance

Akbar Mahdavi-Shakib; K B Sravan Kumar; Todd N Whittaker; Tianze Xie; Lars C Grabow; Robert M Rioux; Bert D Chandler

doi:10.1002/anie.202013359

Kinetics of H₂ Adsorption at the Metal-Support Interface of Au/TiO₂ Catalysts Probed by Broad Background IR Absorbance

Angew Chem Int Ed Engl. 2021 Mar 29;60(14):7735-7743. doi: 10.1002/anie.202013359. Epub 2021 Feb 26.

Authors

Akbar Mahdavi-Shakib¹, K B Sravan Kumar^{1

2}, Todd N Whittaker¹, Tianze Xie³, Lars C Grabow^{2

4}, Robert M Rioux^{3

5}, Bert D Chandler^{1

3

5}

Affiliations

¹ Department of Chemistry, Trinity University, San Antonio, TX, 78212-7200, USA.
² Department of Chemical and Biomolecular Engineering, University of Houston, Houston, TX, 77204-4004, USA.
³ Department of Chemical Engineering, The Pennsylvania State University, University Park, PA, 16802, USA.
⁴ Texas Center for Superconductivity at the, University of Houston (TcSUH), University of Houston, Houston, TX, 77204, USA.
⁵ Department of Chemistry, The Pennsylvania State University, University Park, PA, 16802, USA.

PMID: 33403732
DOI: 10.1002/anie.202013359

Abstract

H₂ adsorption on Au catalysts is weak and reversible, making it difficult to quantitatively study. We demonstrate H₂ adsorption on Au/TiO₂ catalysts results in electron transfer to the support, inducing shifts in the FTIR background. This broad background absorbance (BBA) signal is used to quantify H₂ adsorption; adsorption equilibrium constants are comparable to volumetric adsorption measurements. H₂ adsorption kinetics measured with the BBA show a lower E_app value (23 kJ mol^-1 ) for H₂ adsorption than previously reported from proxy H/D exchange (33 kJ mol^-1 ). We also identify a previously unreported H-O-H bending vibration associated with proton adsorption on electronically distinct Ti-OH metal-support interface sites, providing new insight into the nature and dynamics of H₂ adsorption at the Au/TiO₂ interface.

Keywords: gold catalyst; hydrogen activation; hydroxyl groups; infrared spectroscopy; metal-support interface.

Abstract

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