Elucidation of Active Sites for the Reaction of Ethanol on TiO2/Au(111)

作者：Boyle David T; Wilke Jeremy A; Palomino Robert M; Lam Vivian H; Schlosser Daniel A; Andahazy Wil J; Stopak Cameron Z; Stacchiola Dario J; Rodriguez Jose A; Baber Ashleigh E^*

来源：Journal of Physical Chemistry C, 2017, 121(14): 7794-7802.

DOI：10.1021/acs.jpcc.6b11764

Obtaining a molecular-level understanding of the reaction of alcohols with heterogeneous model catalysts is critical for improving industrial catalytic processes, such as the production of H-2 from alcohols. Gold has been shown to be an excellent oxidation catalyst once oxygen is added to it. The use of reducible oxides provides a source of oxygen on Au(111) for the reaction of ethanol, which is easily regenerated in the presence of an oxygen background. In this work, ethanol operates as a probe molecule to investigate the role of Au(111), TiO2 nanoparticles, and TiO2/Au interfacial surface sites on the catalytic properties of TiO2/Au(111). Ultrahigh vacuum temperature-programmed desorption (TPD) studies with ethanol/Au(111) elucidate previously unreported adsorption sites for ethanol. Ethanol molecularly adsorbs to Au terrace sites, step edges, and undercoordinated kink sites with adsorption energies of -51.7, -55.8, and -65.1 kJ/mol, respectively. A TPD coverage study of ethanol on TiO2/Au(111) indicates ethanol undergoes dissociative adsorption to form H*(a) and CH3CH2O*(a) on the inverse model catalyst surface. The desorption temperature of low coverages of ethanol from TiO2/Au(111) (T-des approximate to 235 K) is at an intermediate temperature between the desorption temperatures from bulk Au(111) and TiO2(110), indicating both Au and TiO2 play a role in the adsorption of ethanol. Both low -temperature adsorption and high -temperature reactions are studied and indicate that ethanol derived products such as acetaldehyde and ethylene desorb from TiO2/Au(111) at similar to 500 K. Herein, we report the identification of catalytically active sites on TiO2/Au(111) as interfacial sites between the oxide and Au(111) surface through the use of temperature-programmed desorption and infrared reflection absorption spectroscopy.

• 出版日期2017-4-13