Ultrafast charge transfer in metal-free HO photoproduction by anhydride modified g-CN.

As a low-cost, low toxicity and metal-free catalyst with strong light absorption, graphitic carbon nitride (g-CN)-based materials have gained wide attention for efficient HO photocatalysis. However, further investigation regarding the charge transfer process and reaction mechanism of HO photoproduction remains to be completed. In this work, bicyclo[2.2.2]oct-7-ene-2,3,5,6-tetracarboxylic dianhydride (BTDA) modified g-CN is synthesized through a facile one-step dehydration process, and the HO 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 HO photoproduction using easily acquired materials with future application potential.