Nanoceria as an Acid–Base Catalyst for Interfacial Hydrolysis of Sulfonylureas: A Combined 31P MAS NMR and DFT Study

Abstract

Understanding coordination-driven bond activation at metal oxide interfaces is essential for predicting the chemical stability of complex organic molecules. Here, we demonstrate that nanoceria efficiently drives the spontaneous, dark hydrolysis of sulfonylureas (amidosulfuron, metsulfuron-methyl, and nicosulfuron) via surface acid–base chemistry under ambient conditions. By combining liquid chromatography–mass spectrometry (LC-HRMS) with density functional theory (DFT) calculations, we show that the degradation proceeds through urea N–C bond cleavage. While the experimental identification of the degradation products confirms the overall hydrolytic pathway, DFT calculations are used to provide unique insights into the specific mechanism, proposing that the reaction is initiated by lattice-oxygen nucleophilic attack leading preferentially to sulfonyl-side N–C bond cleavage. Crucially, solid-state 31P MAS NMR spectroscopy using a trimethylphosphine oxide probe explicitly mapped the distribution and strength of surface Lewis and Brønsted acidic sites (oxygen vacancies and bridging hydroxyls). This provides a molecular-level link between ceria defect structures and their unique interfacial reactivity, highlighting the potential of tailored ceria surfaces to drive spontaneous chemical transformations without external energy inputs.