Fabricating carbon quantum dots of graphitic carbon nitride vis ultrasonic exfoliation for highly efficient H₂O₂...

A promising and sustainable approach for producing hydrogen peroxide is the two-electron oxygen reduction reaction (2e^- ORR), which uses very stable graphitic carbon nitride (g-C₃N₄). However, the catalytic performance of pristine g-C₃N₄ is still far from satisfactory. Here, we demonstrate for the first time the controlled fabrication of carbon quantum dots (CQDs)-modified graphitic carbon nitride carbon (g-C₃N₄/CQDs-X) by ultrasonic stripping for efficient 2e^- ORR electrocatalysis. HRTEM, UV-vis, EPR and EIS analyses are in good consistent which prove the in-situ generation of CQDs. The effect of sonication time on the physical properties and ORR activity of g-C₃N₄ is discussed for the first time. The g-C₃N₄/CQDs-12 catalyst shows a selectivity of up to 95% at a potential of 0.35 V vs. RHE, which is much higher than that of the original g-C₃N₄ catalyst (88%). Additionally, the H₂O₂ yield is up to 1466.6 mmol g^-1 in 12 h, which is twice as high as the original g-C₃N₄ catalyst. It is discovered that the addition of CQDs through ultrasonic improves the g-C₃N₄ catalyst's electrical conductivity and electron transfer capability in addition to its high specific surface area and distinctive porous structure, speeding up the reaction rate. This research offers a green method for enhancing g-C₃N₄ activity.