In situ photocatalytic formation of carbon quantum dots from corn stover via interfacial hydrogen peroxide generation

Abstract

We present a sustainable photocatalytic approach for synthesizing carbon quantum dots (CQDs) from renewable corn stover under simulated solar irradiation. In this process, hydrogen peroxide (H₂O₂) is spontaneously and continuously generated at the gas–water microdroplet interface. Naturally occurring ferrous (Fe²⁺) and other multivalent ions in the corn stover catalyze the decomposition of H₂O₂, producing highly reactive hydroxyl radicals (˙OH) that drive the oxidation and fragmentation of lignocellulosic components, ultimately leading to CQD formation. An oxygen-rich environment further facilitates the reaction. Compared to conventional methods, this approach enhances H₂O₂ utilization efficiency while avoiding excessive oxidation associated with high doses of external oxidants (e.g., H₂O₂ and HNO₃). The resulting CQDs (4.6 ± 0.8 nm) exhibit intense blue fluorescence with a quantum yield of up to 20.1 ± 0.8%. Structural analyses (XRD, FTIR, Raman, NMR, and XPS) confirm their amorphous graphitic nature with nitrogen self-doping. Uniform CQDs with an average size of 3.1 ± 1.4 nm and high purity were obtained through centrifugation and dialysis purification. This low-cost, scalable method, which integrates in situ H₂O₂ generation at the microdroplet interface, offers a promising pathway for environmentally friendly CQD production.