In Situ Oxidation Study of Pt(110) and Its Interaction with CO

Abstract

ABSTRACT:Many interesting structures have been observed for O 2 -exposed Pt(110). These structures, along with their stability and reactivity toward CO, provide insights into catalytic processes on open Pt surfaces, which have similarities to Pt nanoparticle catalysts. In this study, we present results from ambient-pressure X-ray photoelectron spectroscopy, high-pressure scanning tunneling microscopy, and density functional theory calculations. At low oxygen pressure, only chemisorbed oxygen is observed on the Pt(110) surface. At higher pressure (0.5 Torr of O 2 ), nanometer-sized islands of multilayered α-PtO 2 -like surface oxide form along with chemisorbed oxygen. Both chemisorbed oxygen and the surface oxide are removed in the presence of CO, and the rate of disappearance of the surface oxide is close to that of the chemisorbed oxygen at 270 K. The spectroscopic features of the surface oxide are similar to the oxide observed on Pt nanoparticles of a similar size, which provides us an extra incentive to revisit some single-crystal model catalyst surfaces under elevated pressure using in situ tools.

Chemical states of surface oxygen during CO oxidation on Pt(1 1 0) surface revealed by ambient pressure XPS

“…However, it is noteworthy that the evidence of surface oxide on the Pd surface under diffusion limited high-temperature region is indirectly probed with PM-IRAS under the oxygen-rich reaction condition, and no surface oxide is found in the case of the Pt(1 1 0) surface under the identical diffusion limited region [12]. Later, with AP-XPS, Butcher et al confirmed the formation of surface oxide under oxygen-rich environment, yet the reactivity of surface oxide was found not to be significantly higher than that of surface chemisorbed oxygen [23].…”

In Situ Oxidation Study of Pt Nanoparticles on MgO(001)

“…It is necessary to track oxygen-induced nanoparticle shape changes since the exposure of new particle facets may lead to totally different physical particle properties 2,[14][15][16][17] . In addition the CO oxidation mechanism over 4d and 5d transiton metal surfaces and nanoparticles is a topic of current discussion [18][19][20][21][22][23][24][25][26][27] .…”

Time Resolved Operando X-ray Techniques in Catalysis, a Case Study: CO Oxidation by O2 over Pt Surfaces and Alumina Supported Pt Catalysts

“…More recently these XPS studies have been augmented to study CO oxidation catalysis on low index Pt(110) [134] and Pt(111) surfaces [135], just as we have seen, in the previous section, SXRD applied to this problem. Some exemplary results, highlighting aspects of this method, are shown in Figures 8 and 9 from the study of Butcher et al [134] regarding CO oxidation at elevated pressures on Pt (110).…”

“…Some exemplary results, highlighting aspects of this method, are shown in Figures 8 and 9 from the study of Butcher et al [134] regarding CO oxidation at elevated pressures on Pt (110). XPS also brings with it an intrinsic level of surface sensitivity-due to the underlying physics of electron atom interactions that also plays a part in making EXAFS an intrinsically short range probe of local bulk structure-that is not intrinsic to XRD and XAFS as a result of energy of the X-rays, be they incident or fluorescent, applied or detected, generally used in the latter two methods.…”