TY - JOUR
T1 - Co adsorption on Au/Tio2 Catalysts
T2 - Observations, quantification, and explanation of a broad-band infrared signal
AU - Powell, Camilah D.
AU - Daigh, Arthur W.
AU - Pollock, Meagan N.
AU - Chandler, Bert D.
AU - Pursell, Christopher J.
N1 - Funding Information:
The authors gratefully acknowledge the financial support of the U.S. National Science Foundation (CBET-1160217 and CHE-1012395) and the Robert A. Welch Foundation (departmental grant W-0031). These experiments were performed by undergraduate students C.D.P., A.W.D., and M.N.P. under supervision from B.D.C. and C.J.P. at Trinity University. C.D.P. gratefully acknowledges the financial assistance of the Ronald E. McNair Scholars Program at Trinity University, which is funded in part by a grant from the U.S. Department of Education. The manuscript was partially prepared by C.J.P. during his academic sabbatical at the Okinawa Institute of Science and Technology (OIST). He gratefully acknowledges OIST and Trinity University for financial support during his sabbatical. C.J.P. also thanks Professor Mukhles Sowwan for hosting him at OIST.
Publisher Copyright:
© XXXX American Chemical Society.
PY - 2017
Y1 - 2017
N2 - The adsorption of CO on Au/TiO2 catalysts was examined at room temperature using FTIR transmission spectroscopy. Adsorption was observed as (i) a sharp peak at ∼2100 cm-1 due to CO molecular vibration (the Au-CO peak), and (ii) a broad-band infrared (BB-IR) signal. The Au-CO peak and BB-IR signal are correlated and quantitatively related to the amount of CO adsorbed on the Au nanoparticles. For comparison purposes, we also examined CO adsorption on Au/Al2O3 catalysts. When supported on this nonreducible support, CO adsorption on Au showed only the Au-CO peak; the BB-IR signal was absent. This allowed us to determine that the BB-IR signal observed for CO adsorption on the Au/TiO2 catalyst is associated with the reducibility of the support. Comparison of the two catalysts also enabled us to determine that the BB-IR signal is due to a decrease in transmission through the powdered catalysts when CO adsorbs on Au/TiO2. Consistent with previously published studies, we propose that this BB-IR signal is related to the reversible, partial reduction of the TiO2 at the Au-TiO2 interface. This reduction leads to an increase in surface disorder or roughening of TiO2 particles that produces a decrease in IR transmission through the catalyst (i.e. an increase in IR scattering). These results suggest an efficient CO-Au-TiO2 adsorbate-induced electronic metal-support interaction (EMSI) that may play an important role in understanding CO reactions on Au/TiO2 catalysts.
AB - The adsorption of CO on Au/TiO2 catalysts was examined at room temperature using FTIR transmission spectroscopy. Adsorption was observed as (i) a sharp peak at ∼2100 cm-1 due to CO molecular vibration (the Au-CO peak), and (ii) a broad-band infrared (BB-IR) signal. The Au-CO peak and BB-IR signal are correlated and quantitatively related to the amount of CO adsorbed on the Au nanoparticles. For comparison purposes, we also examined CO adsorption on Au/Al2O3 catalysts. When supported on this nonreducible support, CO adsorption on Au showed only the Au-CO peak; the BB-IR signal was absent. This allowed us to determine that the BB-IR signal observed for CO adsorption on the Au/TiO2 catalyst is associated with the reducibility of the support. Comparison of the two catalysts also enabled us to determine that the BB-IR signal is due to a decrease in transmission through the powdered catalysts when CO adsorbs on Au/TiO2. Consistent with previously published studies, we propose that this BB-IR signal is related to the reversible, partial reduction of the TiO2 at the Au-TiO2 interface. This reduction leads to an increase in surface disorder or roughening of TiO2 particles that produces a decrease in IR transmission through the catalyst (i.e. an increase in IR scattering). These results suggest an efficient CO-Au-TiO2 adsorbate-induced electronic metal-support interaction (EMSI) that may play an important role in understanding CO reactions on Au/TiO2 catalysts.
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U2 - 10.1021/acs.jpcc.7b07249
DO - 10.1021/acs.jpcc.7b07249
M3 - Article
AN - SCOPUS:85032750119
SN - 1932-7447
VL - 121
JO - Journal of Physical Chemistry C
JF - Journal of Physical Chemistry C
IS - 39
ER -