Ultrafast charge transfer in metal-free H₂O₂ photoproduction by anhydride modified g-C₃N₄

As a low-cost, low toxicity and metal-free catalyst with strong light absorption, graphitic carbon nitride (g-C₃N₄)-based materials have gained wide attention for efficient H₂O₂ photocatalysis. However, further investigation regarding the charge transfer process and reaction mechanism of H₂O₂ photoproduction remains to be completed. In this work, bicyclo[2.2.2]oct-7-ene-2,3,5,6-tetracarboxylic dianhydride (BTDA) modified g-C₃N₄ is synthesized through a facile one-step dehydration process, and the H₂O₂ photoproduction could reach 22.5 μmol within 8 hours. The proposed structure of g-BTDA is confirmed by FTIR, XPS and SEM studies. The transient absorption reveals a 20.88 ps charge transfer process caused by the electron withdrawing ability of the CO group, and a 2-electron oxygen reduction pathway is proposed. Our work represents a new strategy for efficient H₂O₂ photoproduction using easily acquired materials with future application potential.