Constructing S-scheme heterojunction CsBiBr/BiOBr via in-situ partial conversion to boost photocatalytic N fixation.

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 CsBiBr nanocrystals onto BiOBr hollow nanotube, resulting in the formation of an S-scheme heterojunction CsBiBr/BiOBr. This unique in-situ growth approach imparts a closely contacted interface to the CsBiBr/BiOBr heterojunction, facilitating interfacial electron transfer and spatial charge separation compared to a counterpart (CsBiBr: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 CsBiBr to BiOBr promotes the activation of the NN bond and diminishes the energy barrier associated with the rate-determining step in the N reduction process. Consequently, the CsBiBr/BiOBr heterojunction exhibits highly selective photocatalytic N reduction to NH (nearly 100 %) at a rate of 130 μmol g h under simulated sunlight (100 mW cm), surpassing BiOBr, CsBiBr, and CsBiBr:BiOBr by factors of 6, 4, and 2, respectively.