Kinetics of H 2 Adsorption at the Metal–Support Interface of Au/TiO 2 Catalysts Probed by Broad Background IR Absorbance

H 2 adsorption on Au catalysts is weak and reversible, making it difficult to quantitatively study. We demonstrate H 2 adsorption on Au/TiO 2 catalysts results in electron transfer to the support, inducing shifts in the FTIR background. This broad background absorbance (BBA) signal is used to quantify H 2 adsorption; adsorption equilibrium constants are comparable to volumetric adsorption measurements. H 2 adsorption kinetics measured with the BBA show a lower E app value (23 kJ mol −1 ) for H 2 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 H 2 adsorption at the Au/TiO 2 interface.