Investigating the interfacial properties of halide perovskite/TiO x heterostructures for versatile photocatalytic reactions under sunlight.

Heterostructures of metal halide perovskites and TiO _x are efficient photocatalytic materials owing to the combination of the advantages of each compound, specifically the high absorption coefficients and long charge-carrier lifetimes of perovskites, and efficient photocatalytic activity of TiO _x . However, chemical reduction of CO ₂ using PNC/TiO _x heterostructures without organic solvents has not been reported yet. Here, we report the first solvent-free reduction of CO ₂ using amorphous TiO _x with embedded colloidal perovskite nanocrystals (PNCs). The combination was obtained by carrying out hydrolysis of titanium butoxide (TBOT) on the PNC surface without high-temperature calcination. We proposed a mechanism involving photoexcited electrons being transferred from PNCs to TBOT, enabling photocatalytic reactions using TiO _x under visible-light excitation. We demonstrated efficient visible-light-driven photocatalytic reactions at PNC/TiO _x interfaces, specifically with a CO production rate of 30.43 μmol g ^-1 h ^-1 and accelerated degradation of organic pollutants under natural sunlight. Our work has provided a simple path toward both efficient CO ₂ reduction and photocatalytic degradation of organic dyes.