Electron-Hopping Brings Lattice Strain and High Catalytic Activity in the Low-Temperature Oxidative Coupling of Methane in an Electric Field

Abstract

Detailed reaction mechanisms for the oxidative coupling of methane (OCM) over Ce 2 (WO 4 ) 3 catalysts at low temperatures in an electric field were investigated. The influence of Ce cations in the Ce 2 (WO 4 ) 3 catalyst was evaluated by comparing the OCM activity over various Ln 2 (WO 4 ) 3 (Ln = La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, and Dy) catalysts in an electric field. The electronic states of Ln and W cations and the relationship between the distorted Ce 2 (WO 4 ) 3 structure and methane activation were examined using X-ray absorption fine structure (XAFS) measurements and first-principles calculations. The results reveal that the Ln 2 (WO 4 ) 3 catalysts with redoxactive Ln cations (Ce, Pr, Sm, Eu, and Tb) show OCM activity. First-principles calculations indicate that Ce 3+ species in the Ce 2 (WO 4 ) 3 structure are oxidized to Ce 4+ species in an electric field by extracting electrons from the Ce 4f orbitals near the Fermi level; as a result, its structure is distorted. The results indicate that the redox reaction of Ln cations in Ln 2 (WO 4 ) 3 induced by an electric field brings lattice strain and a high OCM activity in an electric field.

Charge Coupling Enhanced Photocatalytic Activity of BaTiO3/MoO3 Heterostructures

“…The strain can be induced by various factors such as lattice mismatch, thermal coefficient mismatch, grain morphology, lattice distortions, and interlayer charge transfer. , The effect of thermal coefficient mismatch on strain can be excluded because the growth (deposition/annealing) temperature is the same for all the films. In the present study, the lattice distortion and charge transfer mechanism due to the internal field have a predominant contribution to the lattice strain than the other factors.…”

“…This will be further corroborated from the FTIR, PL, and current–voltage ( I – V ) analysis. It is found that the heterostructure with t MoO 3 = 67 nm exhibits a maximum lattice strain which could be possibly due to the interfacial charge transfer and octahedral distortion . This will, in turn, reduce the charge carrier recombination rate which is vital for better photocatalytic efficiency.…”

Recent Developments in Natural Gas Flaring Reduction and Reformation to Energy-Efficient Fuels: A Review

“…However, at temperatures less than 600 °C, creation of active oxygen sites on MgO led to lower activity. Contrary, at low temperature, catalysts such as Ca-Sm 2 O 3 /MgO, Sm 2 O 3 /MgO, and Ca-CeO 2 /MgO exhibited higher yields than those of Li- and Na-based catalysts, due to less active site activation at lower temperature …”

Field-effect surface chemistry: chemical reactions on two-dimensional materials controlled by field-effect transistor configurations

“…Similarly, the V D application can activate the active layer. In the case of the oxidative coupling of methane over cerium tungsten oxide catalysts, the reaction temperature was found to decrease when an electrical current flowed through the catalyst bed [30]. The proposed mechanism involves the activation of lattice oxygen through the oxidation of Ce cations, which enhances the ability of H abstraction from methane.…”