Boosting H₂O₂ production via two-electron oxygen reduction with O-doped g-C₃N₄ decorated with Ti₃C₂T_x quantum dots

Photocatalytic synthesis of H₂O₂ with g-C₃N₄ holds great promise for converting solar energy into chemical energy, but it remains constrained by the narrow optical absorption range and rapid charge recombination. To overcome these challenges, Ti₃C₂T_x MXene quantum dots (TQDs), known for their ease of carrier regulation and strong visible light absorption, were incorporated into O-doped g-C₃N₄ (O-CN) to form TQDs-modified O-CN (O-CN@TQDs) with a Schottky heterojunction. Attributed to such structural design, the H₂O₂ production was promoted through the two-step two-electron oxygen reduction pathway, with O₂^- serving as the primary intermediate. The photocatalytic H₂O₂ production rate over optimized O-CN@TQDs reached 868.9 μmol g^-1 h^-1 under visible light irradiation, which was 10.8 times higher than that of the pristine g-C₃N₄. This study underscores the potential of judiciously selecting suitable semiconductor and metal-like materials to construct Schottky heterojunctions for the efficient photocatalytic production of H₂O₂.