Simulating Temperature Programmed Desorption of Oxygen on Pt(111) Using DFT Derived Coverage Dependent Desorption Barriers
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The dissociative adsorption energy of oxygen on Pt(111) is known to be coverage dependent. Simple Redhead analysis of temperature programmed desorption (TPD) experiments that assumes a coverage independent desorption barrier can lead to errors in estimated properties such as desorption barriers and adsorption energies. A simple correction is to assume a linear coverage dependence of the desorption barrier, but there is usually no formal justification given for that functional form. More advanced TPD analysis methods that are suitable for determining coverage dependent adsorption parameters are limited by their need for large amounts of high quality, low noise data. We present a method to estimate the functional form of the coverage dependent desorption barrier from density functional theory calculations for use in analysis of TPD spectra. Density functional theory was employed to calculate the coverage dependence of the adsorption energy. Simulated TPD spectra were then produced by empirically scaling the DFT based adsorption energies utilizing the Brønstead–Evans–Polyani relationship between adsorption energies and desorption barriers. The resulting simulated spectra show better agreement with the experimental spectra than spectra predicted using barriers that are either coverage-independent or simply linearly dependent on coverage. The empirically derived scaling of the desorption barriers for Pt(111) is shown to be useful in predicting the low coverage desorption barriers for oxygen desorption from other metal surfaces, which showed reasonable agreement with the reported experimental values for those other metals.
KeywordsCoverage dependence Temperature programmed desorption Density functional theory Late transition metals
- 1 .
- 2.Allers KH, Pfnur H, Feulner P, Menzel D (1996) Angle and energy distributions of thermally desorbing oxygen from Pt(111): the influences of a dynamically variable activation barrier. Int J Res Phys Chem Chem Phys 197(Part 1–2):253–268Google Scholar
- 14.Dominik C (2010) The Org Mode 7 Reference Manual: Organize your life with GNU Emacs. Network Theory, UKGoogle Scholar
- 15.Dumesic JA, Rudd DF, Aparicio LM, Rekoske (1993) The microkinetics of heterogeneous catalysis. American Chemical Society, Washington, DCGoogle Scholar
- 16.Fischer-Wolfarth JH, Hartmann J, Farmer JA, Flores-Camacho JM, Campbell CT, Schauermann S, Freund HJ (2011) An improved single crystal adsorption calorimeter for determining gas adsorption and reaction energies on complex model catalysts. Rev Sci Instrum 82:024102Google Scholar
- 25.Ihm H, Ajo HM, Gottfried JM, Bera P, Campbell CT (2004) Calorimetric measurement of the heat of adsorption of benzene on Pt(111). J Phys Chem B 108(38):14627–14633Google Scholar
- 34.Perdew JP, Wang Y (1992) Accurate and simple analytic representation of the electron-gas correlation-energy. Phys Rev B 45(23):13244–13249Google Scholar
- 43.Tang HR, Van der Ven A, Trout BL (2004) Phase diagram of oxygen adsorbed on platinum (111) by first-principles investigation. Phys Rev B 70(4):045,420Google Scholar
- 46.Wartnaby CE, Stuck A, Yee YY, King DA (1996) Microcalorimetric heats of adsorption for CO, NO, and oxygen on Pt(110). J Phys Chem A 100(30):12483–12488Google Scholar