Carbon dots and graphene nanocomposite as an electrocatalyst for selective two electron oxygen reduction to H2O2

Electrochemical synthesis of hydrogen peroxide (H 2 O 2 ) via two-electron oxygen reduction reaction (2e-ORR) offers a sustainable alternative to the anthraquinone process. Herein, a nanocomposite of carbon dots (CDs) and reduced carboxylic acid-functionalized graphene (rCA-G), denoted as CDs@rCA-G, was synthesized via a straightforward single pot hydrothermal method. The prepared CDs@rCA-G was characterized using physicochemical methods. The transmission electron microscopy pictures confirm that CDs are consistently distributed on the surface of graphene nanosheets. Powder X-ray diffraction data demonstrate the amorphous character of CDs and the graphitic structure of rCA-G, while the CDs@rCA-G composite exhibits characteristic peaks of both components, indicating successful integration. Fourier transform infra-red spectroscopy analysis reveals the existence of copious oxygen-carrying functionalities (–OH, carbonyl, and C–O) and confirms the integration of CDs onto the rCA-G framework. The synthesized CDs@rCA-G, employed as an electrocatalyst for oxygen reduction in alkaline condition, displays an onset potential of 0.79 V ( vs. RHE) and a half-wave potential of 0.67 V ( vs. RHE), while demonstrating ~ 85% selectivity toward the two-electron pathway for H 2 O 2 formation. The electron transfer number was computed as 2.1, indicating a dominant two-electron pathway, and the nanocomposite exhibits high stability, creating it a promising material for the long-term, trade-scale manufacture of H 2 O 2 through oxygen reduction.