Utilizing the Undesirable Oxidation of Lead-Free Hybrid Halide Perovskite Nanosheets for Solar-Driven Photocatalytic C(sp³)─H Activation: Unraveling the Serendipity

Hybrid halide perovskites (HHPs), whose every branch generates intrusiveness, have been utilized in solar cells from a broader perspective. However, the inclusiveness of employing HHP as a photocatalyst is in its initial stage. This study mainly focuses on the unexpected utilization of, so far, undesirable material vacancy-ordered MA₂SnBr₆ quantum dots synthesized from MASnBr₃ nanosheets. Here, the quantum confinement grounded a large blue shift in ultraviolet (UV) and photoluminescence (PL) spectra with a Stokes shift of 420 meV, where the band gap increase is observed as size decreases in MA₂SnBr₆. Remarkably, MA₂SnBr₆ exhibits air and moisture stability, better charge transfer, and high oxidation potential compared to MASnBr₃. The first-principles-based atomistic computations reveal the strain relaxation in the Sn-Br framework that structurally stabilizes the MA₂SnBr₆ lattice. Furthermore, the direct band gap and strongly localized valence band edge give rise to a new potential photocatalyst MA₂SnBr₆ for efficient solar-driven C(sp³)─H activation of cyclohexane and toluene under ambient conditions.