Designing CeTiO_x-based composite encapsulation overlayer on platinum for enhanced methanol steam reforming

Area of Science:

• Catalysis Science and Engineering
• Materials Science for Energy Applications
• Surface Chemistry and Heterogeneous Catalysis

Background:

• Methanol steam reforming (MSR) is crucial for sustainable hydrogen production.
• Conventional catalysts suffer from low efficiency due to sluggish reaction steps and poor selectivity.
• Encapsulation overlayers offer a strategy to improve catalyst performance.

Purpose of the Study:

• To develop a novel composite encapsulation overlayer catalyst for enhanced MSR.
• To investigate the structure-activity relationship of the Pt-5CeTiOₓ catalyst.
• To elucidate the reaction mechanism and identify key intermediates.

Main Methods:

• Synthesis of Pt-5CeTiOₓ catalyst with a composite CeTiOₓ overlayer.
• Quasi in situ X-ray photoelectron spectroscopy (XPS) for structural analysis.
• Temperature-programmed desorption (TPD), TPSR, and in situ DRIFTS for mechanistic studies.
• Density functional theory (DFT) calculations for theoretical validation.

Main Results:

• A unique multilayer structure with an inner CeOₓ-rich layer and outer TiO₂₋ₓ shell was formed.
• The composite overlayer stabilized Pt, promoted key C-H bond cleavage, and facilitated water dissociation.
• The Pt-5CeTiOₓ catalyst showed a 1.56-fold increase in MSR activity and >80% CO selectivity reduction compared to controls.

Conclusions:

• Rationally designed composite encapsulation overlayers significantly enhance MSR performance.
• The inverse Ce³⁺-OVs-(Pt⁰-Ptᵟ⁺) configuration is key to the improved catalytic activity and selectivity.
• This work presents a viable strategy for advancing catalyst design through composite overlayer architectures.