Boosted hydrogen peroxide production photocatalyzed by thiophene-based D-A covalent triazine frameworks via modulating two-electron oxygen reduction pathway

Photocatalytic one-step two-electron oxygen reduction reaction (direct 2e- ORR) holds significant potential for efficient hydrogen peroxide (H2O2) production, however, research on achieving direct 2e- ORR by regulating the active sites in catalysts remains a challenge. Herein, two covalent triazine frameworks (CTFs), named CTF-Th and CTF-Na, were constructed from thieno[3,2-b]thiophene and naphthalene monomers respectively for photosynthesis of H2O2. Compared with CTF-Na, the electron-donating thieno[3,2-b]thiophene imparted CTF-Th with enhanced visible light absorption and efficient charge carrier separation, therefore CTF-Th achieved excellent H2O2 production rate (4.77 mmol h- 1 g- 1) in pure water and exhibited an impressive H2O2 rate of 46.84 mmol h- 1 g- 1 in the benzyl alcohol/water system, surpassing the majority of metal-free catalysts reported under similar conditions. In addition, experiments and DFT calculations revealed that the sulfur atom in CTF-Th effectively regulated the microenvironment of active sites for ORR, thereby resulting in efficient H2O2 production through direct 2e- ORR pathway.