The construction of Cs3MoxSbyBr9/BiVO4 S-scheme heterojunction photocatalyst for efficient photocatalytic N2 fixation.

A novel S-scheme heterojunction of Cs 3 Mo x Sb y Br 9 /BiVO 4 has been developed for the photocatalytic coupling of N 2 fixation and H 2 O oxidation. It presents a simultaneous enhancement for redox capacities, exhibiting excellent photocatalytic N 2 reduction to NH 3 activity (300 μmol g−1 h−1) under simulated solar light illumination (100 mW cm−2). [Display omitted] • This work marks the inaugural utilization of lead-free halide perovskite in photocatalytic N 2 fixation. • Attributing to the electronic structure regulation and S-scheme heterojunction design, Cs 3 Mo x Sb y Br 9 /BiVO 4 achieves efficient N 2 photoreduction with H 2 O as the electron source. • The photocatalytic mechanism is explored through theoretical calculation and in-situ characterization. Synergistic nitrogen (N 2) reduction with water (H 2 O) oxidation is meaningful but challenging owing to the inertness of the N 2 molecule and the sluggish kinetics of H 2 O oxidation. Herein, a simutaneous-promotion strategy of redox capacities is presented for constructing a lead-free Cs 3 Sb 2 Br 9 -based S-scheme heterojunction, by decorating Mo-functionalized Cs 3 Sb 2 Br 9 nanocrystals (Cs 3 Mo x Sb y Br 9) on BiVO 4 nanosheet through an in-situ plane-to-point growth manner. The Mo-functionalization for Cs 3 Sb 2 Br 9 enables the regulation of the d-band center position, greatly improving surface reaction kinetics for N 2 reduction. Furthermore, the construction of the S-scheme heterojunction enhances the driving force for H 2 O oxidation and spatial charge separation of photocatalysts. As anticipated, the resultant Cs 3 Mo x Sb y Br 9 /BiVO 4 exhibits an excellent photocatalytic N 2 reduction activity under ambient atmosphere, achieving ammonia (NH 3) production at a rate of 300 ± 5 μmol g−1 h−1 under simulated sunlight illumination (100 mW cm−2), which is nearly 20-fold higher than that of pristine Cs 3 Sb 2 Br 9. [ABSTRACT FROM AUTHOR]