TiO2/CDs/g-C3N4 heterojunction: synthesis, characterization and its enhanced photocatalytic C(sp3)-O bond formation under blue LED illumination

Photoredox catalysis has developed as an effective and adaptable tool for generating novel synthesis procedures. Among its different variants, heterogeneous photoredox catalysis stands out for many significant energy efficiency benefits. Herein, we examined a ternary TiO2/CDs/g-C3N4 (TCC) heterojunction as a photocatalyst for promoting C(sp3)-O bond formation upon illumination with blue LED light. A 10 wt% loading of TiO2 on carbon dots/g-C3N4 (CDCN) showed the best efficiency in the photocatalytic C(sp3)-O bond formation. The structural, optical, electronic properties, surface morphology, topography, functional group analysis, chemical states and elemental composition were characterized using various analysis techniques. HRTEM analysis shows the presence of spherical, monodispersed carbon dots (CDs) with a mean particle size of 6 nm. The CDs in the nanocomposite act as an electron mediator, thus forming a Z-scheme heterojunction between two semiconductors. The average diameter and d-spacing value of TiO2 on CDCN are assessed to be 12 and 0.23 nm, respectively. Further, the production of photoexcited holes and electrons during the photocatalytic process has been identified with the help of scavenging studies. The prepared photocatalyst shows excellent product yields of up to 99% within 5 h of reaction time with high turnover number (TON) and turnover frequency (TOF).