Easy Preparation of Carbon Nano Onion—Poly Ionic Liquid-Like Hybrids Through the Deep Eutectic Monomer (DEM) Approach and Their Use in Heterogeneous Catalysis

Carbon nano-onions (CNOs) are efficiently functionalized using a sustainable approach based on polymerizable deep eutectic solvents (PDESs), or deep eutectic monomers (DEMs). These systems replace conventional organic solvents, acting simultaneously as dispersing media and functionalization reagents. The method enables the rapid introduction of functional groups such as –OH, –NH3⁺Br−, and –SO3− onto CNO surfaces. The resulting materials are comprehensively characterized by TGA, 13C-CPMAS-TOSS NMR, FT-IR spectroscopy, TEM, AFM, DLS, and XPS. Notably, sulfonate-functionalized CNOs support the Keggin-type polyoxometalate H3PW12O40 (PW12), which acts as a recyclable heterogeneous catalyst for the oxidation of alcohols to carbonyl compounds.