Toward an Active Site–Performance Relationship for Oxide-Supported Single and Few Atoms

The directional regulation of product distribution is contingent upon the rational design of catalytically active sites, wherein a lucid comprehension of active site–performance relationships (APR) is indispensable. We employed syngas conversion as a prototypical reaction, and the dynamic evolution of APR across different neighboring density (ND) active sites was elucidated. The variability in APR is predominantly attributed to the alterations in the structure and electronic environment, which induce differential behavior in the adsorption/activation of reactants and the adsorption/desorption of intermediates. As the pivotal rate-limiting step, the adsorption–desorption dynamics of formaldehyde on Mo sites critically govern product distribution; with the increased ND, the product distribution changes from aromatics to low-chain alkanes. Fundamentally, the disparity in adsorption behavior stems from the heterogeneity or homogeneity of the charge environment conferred by the adsorption sites. Moreover, the catalytic reactivity depends on the density and accessibility of the active sites on the catalyst. This study designs a class of syngas conversion catalyst prototypes with active sites at varying ND, elucidating the dynamic evolution of APR and providing a critical theoretical foundation for the selective modulation of catalytic performance.