Ultrafast Sunlight-Driven PhotocatalyticOxidation of 3,3′,5,5′-Tetramethylbenzidine within 10 s by H2O to ·OH Using Nitrogen-Doped Carbon Dots

Photocatalytic systems often suffer from rapid charge recombination and demanding operational requirements. Current photocatalytic oxidation reactions often require the addition of external oxidants. Herein, we develop nitrogen-doped carbon dots (CDs) as a highly efficient photocatalyst with H 2 O as electron acceptors. The optimized CDs achieve exceptional degradation of methyl orange and rhodamine B with rate constants of 0.275 min -1 and 0.307 min -1 , significantly surpassing many reported catalysts. Under ambient sunlight, they rapidly oxidize TMB within 10 s by generating hydroxyl radicals (·OH) from H 2 O. Nitrogen doping elevates the valence band to 2.94 eV, exceeding the ·OH formation potential, while pyrrole N and the conjugated π-system enhance water adsorption and electron transfer. Radical trapping confirms ·OH as the primary active species. This work provides a new paradigm for solar-driven oxidation via rational molecular-level design.