Constructing S-scheme heterojunction Cs₃Bi₂Br₉/BiOBr via in-situ partial conversion to boost photocatalytic N₂...

The judicious construction of interfaces with swift charge communication to enhance the utilization efficiency of photogenerated carriers is a viable strategy for boosting the photocatalytic performance of heterojunctions. Herein, an in-situ partial conversion strategy is reported for decorating lead-free halide perovskite Cs₃Bi₂Br₉ nanocrystals onto BiOBr hollow nanotube, resulting in the formation of an S-scheme heterojunction Cs₃Bi₂Br₉/BiOBr. This unique in-situ growth approach imparts a closely contacted interface to the Cs₃Bi₂Br₉/BiOBr heterojunction, facilitating interfacial electron transfer and spatial charge separation compared to a counterpart (Cs₃Bi₂Br₉:BiOBr) fabricated via traditional electrostatic self-assembly. Additionally, the establishment of an S-scheme charge transfer pathway preserves the robust redox capability of photogenerated carriers. Furthermore, the free electron transfer from Cs₃Bi₂Br₉ to BiOBr promotes the activation of the NN bond and diminishes the energy barrier associated with the rate-determining step in the N₂ reduction process. Consequently, the Cs₃Bi₂Br₉/BiOBr heterojunction exhibits highly selective photocatalytic N₂ reduction to NH₃ (nearly 100 %) at a rate of 130 μmol g^-1 h^-1 under simulated sunlight (100 mW cm^-2), surpassing BiOBr, Cs₃Bi₂Br₉, and Cs₃Bi₂Br₉:BiOBr by factors of 6, 4, and 2, respectively.