It has been shown the crystal planes of tin dioxide (SnO2) play a critical role in the observed reduction properties and the resulting surface chemistries. SnO2 has been extensively studied due to its versatility in many areas of interest such as oxidation catalysis, transparent oxide conductors, and gas sensing. It has been recently demonstrated that the oxidation of volatile organic compounds (VOCs) over SnO2 surfaces is possible, where 2-propanol was used as a representative VOC. In UHV, the transition from a stoichiometric to a reduced SnO2(101) surface occurs at temperatures above 500 K, which is a higher temperature than observed for SnO2(110). The dual valency of the Sn enables the reduction of the SnO2 surface and a transition from the Sn+4 to the Sn+2 state. Furthermore, recent studies indicate the ratio of Sn+2/Sn+4 on SnO2 nanomaterials strongly impact the activity of the oxidation of carbon monoxide. For this study, we have utilized ambient pressure X-ray photoelectron spectroscopy (AP-XPS) and low energy electron diffraction (LEED) to characterize the surface chemistry of 2-propanol on well-defined SnO2(101) surfaces. These results will be compared to similar studies performed on a SnO2(110) surface. This allows a direct comparison of the catalytic properties and the electronic states of the two surface terminations. Further investigations using AP-XPS were done on the SnO2(101) in the presence of 2-propanol up to 1 mbar, various 2-propanol/O2 ratios, and over a range of temperatures. By using valence-band spectra during reaction conditions we confirm the transition of Sn+4 to Sn+2 in the presence of 2-propanol. The reaction selectivities will be compared for the various reaction conditions for SnO2(101) and SnO2(110) and will be related to the surface atomic structure.

Reaction of 2-propanol on SnO2(101) studied using ambient-pressure X-ray photoelectron spectroscopy

ACS Spring Meeting 2021

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