Insight into the transient inactivation effect on Au/TiO2 catalyst by in-situ DRIFT and UV–vis spectroscopy

Abstract

Au catalysts have drawn broad attention for catalytic CO oxidation. However, a molecular-level understanding of the reaction mechanism on a fast time-resolved scale is still lacking. Herein, we apply in situ DRIFTS and UV-Vis spectroscopy to monitor the rapid dynamic changes during CO oxidation over Au/TiO2. A pronounced transient inactivation effect likely due to a structural change of Au/TiO2 induced by the reactants (CO and O2) is observed at the beginning of the reaction. The transient inactivation effect is affected by the ratio of CO and O2 concentrations. More importantly, during the unstable state, the electronic properties of the Au particles change, as indicated by the shift of the CO stretching vibration. UV-Vis spectroscopy corroborates the structure change of Au/TiO2 surface induced by the reactants, which leads to a weakening of the Au catalyst’s ability to be oxidized (less O2 adsorption), resulting in the transient inactivation effect.

Revealing the Selective Bifunctional Electrocatalytic Sites via In Situ Irradiated X‐Ray Photoelectron Spectroscopy for Lithium–Sulfur Battery

“…Similarly, there are two peaks that can be confirmed at 458.4 and 464.1 eV in the high‐resolution Ti 2p spectrum of TCNF (Figure S6b, Supporting Information). [ 44 ] In the high‐resolution Ni 2p spectra of NTCNF (Figure 1i), two characteristic peaks at 852.89 and 871.70 eV correspond to the Ni 2p 1/2 and Ni 2p 3/2 of Ni element of NTCNF, respectively. [ 20 ] Two evident peaks with respect to Ni 2+ and shakeup satellites are located at 857.60 and 877.50 eV, due to the bonding of Ni with the oxide from surface oxidation.…”

Very Low Temperature CO Oxidation over Atomically Precise Au25 Nanoclusters on MnO2

“…DRIFT spectra were measured on a Bruker Equinox 55 FTIR spectrometer equipped with a liquid-nitrogen-cooled MCT detector at a resolution of 8 cm –1 resolution. Catalyst powder was placed in a home-built cell (volume = 67.4 μL) . The inlet of the cell was connected to an automated 4-way valve (VICI Valco).…”

“…Catalyst powder was placed in a home-built cell (volume = 67.4 μL). 50 The inlet of the cell was connected to an automated 4-way valve (VICI Valco). Before the catalytic reaction, the sample was pretreated in situ by flowing reactant gas (1% CO and 10% O 2 in He) at different temperatures for 30 min.…”

“…Before the catalytic reaction, the sample was pretreated in situ by flowing reactant gas (1% CO and 10% O 2 in He) at different temperatures for 30 min. Modulation excitation spectroscopy (MES) experiments were performed by periodically switching between two different gas atmospheres according to the following sequences: 50 (i) for CO adsorption, 1% of CO in He and pure He, and (ii) for CO oxidation, 1% of CO and 10% of O 2 in He and pure He. The flow rate was 30 mL min −1 .…”

In Situ UV–Vis–NIR Absorption Spectroscopy and Catalysis

“…In the most accepted hypotheses, adsorption and catalysis occur at the gold−support interface. 124,125 126 FTIR results showed a sudden intensity increase of the CO vibrational band together with an intensity decrease of the CO 2 band and a red-shift of the CO band. The increase of the adsorbed CO band was not related to an increase of the CO 2 formation rate, indicating that during this unstable state the O 2 coverage was decreased probably due to structural changes on the Au/TiO 2 surface, which were tracked by in situ UV−vis−NIR reflectance spectroscopy.…”