Two-Dimensional Submonolayer Pt Clusters with Optimal Pt⁰-Pt^δ+ Sites for Efficient Methylcyclohexane Dehydrogenation

Area of Science:

• Heterogeneous catalysis
• Materials science
• Hydrogen storage technology

Background:

• Methylcyclohexane dehydrogenation (MCHDH) is crucial for hydrogen storage and transport.
• The precise atomic structure of active platinum (Pt) sites in Pt/Al2O3 catalysts for MCHDH remains unclear.
• Subnanometer characterization is needed to understand Pt site structure and C-H activation mechanisms.

Purpose of the Study:

• To elucidate the atomic-scale structure of optimal active Pt sites for MCHDH.
• To investigate the relationship between Pt cluster structure and catalytic performance.
• To develop highly active and selective catalysts for MCHDH.

Main Methods:

• Comprehensive structural characterizations.
• Density functional theory (DFT) calculations.
• Catalytic performance testing of Pt catalysts with varying structures (2D SLCs, single atoms, nanoparticles).

Main Results:

• Identified optimal active sites as 2D submonolayer clusters (SLCs) interfaced with γ-Al2O3.
• Demonstrated that an appropriate ratio of Ptδ+ to Pt0 forms superior Pt0-Ptδ+ interfacial sites.
• Achieved a reaction rate of 29,353 mmol gPt−1 min−1 with 99.98% toluene selectivity using Pt 2D SLCs, outperforming Pt single atoms and nanoparticles.

Conclusions:

• Atomic-scale 2D Pt SLCs with optimal Pt0-Ptδ+ interfaces significantly enhance MCHDH activity and selectivity.
• The electronic properties (5d-electron domination) and interfacial sites facilitate sequential C-H bond activation and toluene desorption.
• Constructing 2D submonolayer metal clusters is a promising strategy for designing efficient catalysts for selective C-H activation.