Metal-Metal Oxide Interaction Modulated Photocatalytic Methane Conversion

Area of Science:

• Heterogeneous Catalysis
• Materials Science
• Surface Chemistry
• Photocatalysis

Background:

• Metal-metal oxide (M-MO) interactions are crucial in catalysis, yet their precise role in modulating lattice oxygen activity and stabilizing reaction intermediates remains unclear.
• Understanding these interactions is vital for advancing catalytic processes like photocatalytic oxidative coupling of methane (POCM).

Purpose of the Study:

• To develop a simple, predictive model for M-MO interactions in POCM.
• To establish a quantitative framework linking M-MO interfacial properties to catalytic activity and selectivity.
• To enable rational design of M-MO photocatalysts for efficient methane conversion.

Main Methods:

• Development of a predictive model based on oxygen vacancy formation energy (E_OV) and methyl adsorption energy difference (ΔE_*CH3).
• Correlation of E_OV and ΔE_*CH3 with photocatalytic activity and selectivity in POCM.
• Experimental validation using a AgPd/TiO2 catalyst.

Main Results:

• E_OV governs lattice oxygen reactivity and C-H activation, while ΔE_*CH3 controls methyl distribution and C-C coupling selectivity.
• Optimal methane conversion requires moderately labile lattice oxygen and large ΔE_*CH3 for selective C-C bond formation.
• The AgPd/TiO2 catalyst demonstrated high methane conversion (30 mmol g⁻¹ h⁻¹), C2 selectivity (92%), and stability (160 h).

Conclusions:

• The E_OV-ΔE_*CH3 framework provides a unifying principle and predictive descriptor map for M-MO photocatalysts in POCM.
• Interfacial synergy is the principal determinant of M-MO photocatalyst performance.
• This study enables rational design of M-MO catalysts by quantifying M-MO interactions.