We investigate the viability of using doped metal oxides for low-temperature methane activation from first principles. We find methane chemisorption occuring on substitutionally doped TiO2 anatase (101) and rutile (110), with the latter exhibiting the best performance. A total of 30 dopants from the period 4-6 d-block transition metals were screened for rutile TiO2, with Rh, Pd, Os, Ir, and Pt having chemisorption energies ranging from -0.32 to -0.62 eV compared to -0.36 eV obtained on rutile IrO2. Detailed electronic structure analysis shows orbital overlap and mixing for chemisorbing dopants, as well as charge localization between the molecule and the surface demonstrating the presence of chemical bonding. For all aforementioned elements, facile C-H dissociation occurs with transition state energies lower than desorption energies, and were more negative than IrO2. Calculations were corroborated at the GGA, GGA + dispersion, meta-GGA and hybrid functional level and found to reach similar conclusions. We predict low-temperature methane activation for Pt, Ir, Pd, Rh, Os doped TiO2, which can be promising catalysts for economical, energy efficient, and selective methane conversion.

Predicting low-temperature methane activation via doped metal oxides from first principles

255th National Meeting (2018)

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