Enhanced photocatalytic CO2 reduction over diatomite-supported TiO2@NH2-MIL-125 S-scheme heterojunction: Intensified charge separation driven by built-in electric field

The development of heterojunction photocatalysts is pivotal in enhancing charge transfer and inhibiting the recombination of photoexcited electron-hole pairs, which is an effective strategy to improve CO 2 conversion. In this study, we have been assembled the TiO 2 @NH 2 -MIL-125 S-scheme heterojunction on the surface of diatomite. Comprehensive characterization confirms the S-scheme charge transfer pathway, which not only promotes preferential accumulation of photogenerated charges at catalytically active sites but also enables rapid, low-resistance charge separation and migration. Meanwhile, the introduction of diatomite improves the dispersion of the active components and accelerates the separation of photogenerated carriers driven by the built-in electric field. Consequently, the TiO 2 @NH 2 -MIL-125/diatomite composite exhibits selective photocatalytic CO 2 to CO conversion without requiring sacrificial reagents. The composite achieves a CO evolution rate of 13.53 μmol g −1  h −1 , which is 2.20 times and 1.33 times higher than pure TiO 2 and the binary TiO 2 @NH 2 -MIL-125 composite, respectively. Furthermore, the composite maintains a stable CO production rate after three reaction cycles. This study presents an approach to designing mineral-supported S-scheme heterojunction photocatalysts for solar energy conversion applications.