Two-Dimensional Submonolayer Pt Clusters with Optimal Pt⁰–Ptδ+ Sites for Efficient Methylcyclohexane Dehydrogenation

Methylcyclohexane dehydrogenation (MCHDH) is vital in hydrogen storage and carriage technologies. However, Pt/Al2O3, as a classic practical catalyst for MCHDH, remains ambiguous regarding the catalytic structure of active Pt sites for C–H activation at the atomic scale due to a shortage of subnanometer characterization. Here, based on comprehensive structural characterizations and density functional theory (DFT) calculations, we demonstrate optimal active Pt sites: two-dimensional (2D) submonolayer clusters (SLCs) interfaced with γ-Al2O3 with an appropriate ratio of Ptδ+ to Pt0 to form optimal Pt0–Ptδ+ interfacial sites that have superior activity for the MCHDH reaction. This SLC's catalyst achieves a reaction rate of up to 29,353 mmol gPt–1 min–1 at 320 °C, with a 99.98% selectivity for toluene over MCHDH, which is significantly better than that of the corresponding Pt single atoms and conventional Pt nanoparticles (NPs) catalysts. The excellent MCHDH performance of Pt 2D SLCs is attributed to their sufficient 5d-electron domination and the optimal Pt0–Ptδ+ sites, which facilitate the sequential activation of multiple C–H bonds and toluene desorption. In comparison, the presence of too many continuous Pt0–Pt0 sites in Pt 2D SLCs can hinder these processes. Our study highlights that constructing atomic-scale 2D submonolayer metal clusters is a promising strategy for optimizing efficient catalysts with abundant M0–Mδ+ (M = metal) sites, enhancing the catalytic performance for selective C–H bond activation.