Bifunctional TiO2/COF S-scheme photocatalyst with enhanced H2O2 production and furoic acid synthesis mechanism

Coupling photocatalytic H2O2 evolution with simultaneous furfuryl alcohol oxidation can avoid the slow water oxidation reaction and fully utilize photogenerated carriers to produce valuable chemicals. Herein, a COF (denoted as BTTA) was synthesized by the Schiff-base condensation and in-situ grown on the surface of TiO2 nanofibers. The resultant TiO2/BTTA composite has a large interface and a short carrier migration distance. Furthermore, the porous and ultrathin BTTA layers endow the composites abundant active sites and excellent light absorption ability. Remarkably, a H2O2-evolution rate of 740 & mu;mol L-1 h-1 and a furoic alcohol conversion of 96 % are achieved. In-situ irradiated X-ray photoelectron spectroscopy and electron spin resonance confirm the S-scheme carrier transfer mechanism, which spatially separates photogenerated carriers with strong redox power. This work opens a new door to the rational design of S-scheme photocatalysts for economic and green photosynthesis of H2O2 and organic compounds.