Lead-free perovskite/metal oxide heterojunction photocatalyst for sustainable Toluene Oxidation

An important field of study is the ecologically benign synthesis of useful compounds such as benzaldehyde and benzyl alcohol from the organic contaminant toluene. Lead-free halide perovskites are excellent options for photocatalysis due to their exceptional photoelectric properties. Nonetheless, they have notable challenges, such as fast charge recombination and ineffective charge separation. In this work, we present a simple anti-solvent technique to create a heterojunction between lead-free halide perovskite Cs2AgBiBr6 (CABB) with Cu2O and Cu-Cu2O. This combination facilitates the photocatalytic activation of C(sp3)−H bonds, which in turn increases the oxidation of toluene. The Cu2O and Cu-Cu2O creating a Z-scheme heterojunction with CABB significantly increases the photocatalytic activity of the CABB/Cu2O and CABB/Cu-Cu2O composites. Approximately 1.3 and 1.7 times greater than the 1212 µmol/g·h generated by pure CABB, the CABB/Cu2O (4:1) and CABB/Cu-Cu2O (4:1) composites produced benzaldehyde at rates of 1576 µmol/g·h and 2034 µmol/g·h, respectively. Additionally, the selectivity for benzaldehyde was ≥99% and 75%, respectively, compared to 53% for pure CABB. These findings might contribute to the development of lead-free perovskites for use in photocatalysis.