Reactivity of Gas-Phase Metal Clusters: Unlocking Mechanisms of Activation and Conversion of Small Molecules

Activation and conversion of very stable and abundantly available molecules such as methane (CH₄), nitrogen (N₂), carbon dioxide (CO₂), and so on into value-added products under mild conditions represents a critical issue in energy and environmental chemistry. Gas-phase cluster reactivity studies, conducted in isolated and interference-free environments, can provide fundamental insights into the activation and transformation of inert chemical bonds at a molecular-level, thereby informing the rational design of efficient catalysts. This perspective article summarizes the research progress over the past five years in the activation and conversion of CH₄, N₂, CO_x (x = 1 and 2), and other molecules mediated by gas-phase metal clusters investigated by both the traditional experimental/theoretical methods and the emerging techniques based on artificial intelligence. Novel reaction pathways covering both elementary and catalytic reactions as well as new electronic and geometric factors governing metal cluster reactivity have been introduced. Machine learning models constructed for the quantitative structure-activity relationship of metal clusters that enable the rapid and reliable reactivity prediction of metal clusters have also been presented. These fruitful results offer fresh perspectives for practical catalytic systems and are helpful to develop advanced catalytic materials for the transformation of CH₄, N₂, CO_x, and other molecules under mild conditions.