Mechanistic insights into methane activation over zirconium-based metal-organic framework-supported transition...

Zirconium-based metal-organic frameworks (Zr-based MOFs) are promising supports for metal-based catalysts that can activate methane. In this study, we investigate all possible methane activation pathways and the potential active sites within the Co - O system supported on the Zr-based MOF NU-1000, complemented by extrapolations to first-row transition metal compounds. The potential energy surface (PES) and electronic structure analyses demonstrate that nearly all supported metals can follow two distinct pathways for methane activation: hydrogen-atom transfer (HAT) and proton-coupled electron transfer (PCET), with the preferred mechanism strongly dependent on the nature of metals. Early transition metals predominantly follow the PCET mechanism, whereas late transition metals favor the HAT mechanism and show significantly higher activity. Moving beyond conventional approaches that focus solely on loaded metal active sites, this work demonstrates that the loaded transition metals can induce cooperate with Zr in NU-1000, activating the framework itself as an active center and enabling methane activation via a bimetallic synergistic mechanism. Particularly in late transition metals, this synergistic effect facilitates electron transfer between the two metal centers, optimizes their electronic structures, and lowers the energy of acceptor orbitals, collectively enhancing electron transfer efficiency. These findings highlight the critical importance of metal-MOF synergy and offer valuable theoretical insights for the rational design of highly efficient catalysts for methane activation.