Role of the Interface between Pd and PdO in Methane Dissociation

Abstract

Dissociation of the first C–H bond of methane was investigated at the interface of partial PdO(101) monolayer and supporting Pd(100) surface with density functional calculations. Activation pathways of CH4 on the bulk PdO(100), PdO(101), Pd(100), and Pd(100) supported PdO(101) monolayer surfaces were also examined. The PdO(101)@Pd(100) boundary enables several new routes for methane dissociation compared to the bulk surfaces, the lowest activation energy barrier being 0.8 eV. The barrier on the most stable and dominant bulk PdO(100) surface is as high as 1.2 eV, whereas on the lower proportion bulk PdO(101) surface it is only 0.5 eV. However, the corresponding barrier increases to 1.2 eV in the case of supported PdO(101) monolayer. A low activation energy of 0.7 eV is observed also on the Pd(100) surface, however, the reaction enthalpy on the metal surface is not as favored as on oxide surfaces or at the phase boundary. Hydrogen diffusion from metal to oxide phase can improve the reaction enthalpy, but it causes increase in the total activation energy. Overall, the results indicate that the presence of phase boundary between PdO and Pd enhances the activity in methane combustion, rationalizing experimental findings.

The Positive Effects of Nanoclay on the Hydraulic Conductivity of Compacted Kahrizak Clay Permeated With Landfill Leachate

“…14 found to be low on the under‐coordinated site. This result is supported by other ultra high vacuum studies of methane adsorption on PdO(101) 15, 16.…”

“…Methane adsorption and dissociation was investigated over the (101) surface cut from a tetragonal bulk lattice. As only PdO adopts this structure, the other oxides should be considered as model systems that allow investigation of the electronic reasons for the low activation energy previously reported for methane dissociation over PdO(101) 14–16. The investigated metals are chosen to probe how the filling of the d‐shell affects the methane dissociation energy.…”

Iridium Oxide Nanoparticles and Iridium/Iridium Oxide Nanocomposites: Photochemical Fabrication and Application in Catalytic Reduction of 4-Nitrophenol

“…28 35 and Au/Au 2 O 3 , 36 have been reported in previous works, proving that the interface between metal and metal oxide is beneficial for improving the catalytic activity of pristine metal catalysts. However, little attention is paid to the Ir/IrO x system.…”

PdO nanoparticles enhancing the catalytic activity of Pd/carbon nanotubes for 4-nitrophenol reduction

“…14 Meanwhile, there exists some evidence showing that the Pd/PdO nanoparticles can enhance the catalytic activity in comparison with Pd nanoparticles in catalysis, 15,16 since the complex electron interaction between the Pd and PdO component, 17 and the reaction activity on the metal surface is not as high as at the phase boundary of Pd and PdO component in methane dissociation. 18 Therefore, it is interesting and meaningful to develop the high efficient Pd/PdO catalysts.…”