Surface Coordination Chemistry of Graphitic Carbon Nitride from Ag Molecular Probes.

Abstract

Graphitic carbon nitride (g-C₃N₄) has gained significant attention for its catalytic properties, especially in the development of Single Atom Catalysts (SACs). However, the surface chemistry underlying the formation of these isolated metal sites remains poorly understood. In this study we employ Surface OrganoMetallic Chemistry (SOMC) together with advanced microscopic and spectroscopic techniques for an in-depth analysis of functionalized g-C₃N₄ materials, where tailored organosilver probe molecules are used to monitor surface processes and characterize resulting surface species. A multi-technique approach - including high-angle annular dark-field scanning transmission electron microscopy (HAADF-STEM), X-ray absorption spectroscopy (XAS), and multinuclear solid-state Nuclear Magnetic Resonance spectroscopy (ssNMR), coupled with density functional theory (DFT) calculations - identifies three primary surface species in Ag-functionalized g-C₃N₄: bis-NHC-Ag⁺, dispersed Ag⁺ sites, and physisorbed molecular precursor. These findings highlight a dynamic grafting process and provide insights into the surface coordination chemistry of functionalized g-C₃N₄ materials.