In Situ Construction of Lead‐Free Perovskite Direct Z‐Scheme Heterojunction Cs₃Bi₂I₉/Bi₂WO₆ for Efficient Photocatalysis of CO₂ Reduction

Abstract

The well‐known toxicity of lead‐halide‐perovskite (LHP) nanocrystals limits their commercial applications in photocatalysis. Herein, an in situ controlled growth strategy is reported for lead‐free perovskite nanocrystals (Cs3Bi2I9) on the surface of ultrathin Bi2WO6 nanosheets through co‐sharing Bi atoms, to generate a direct Z‐scheme heterojunction of Cs3Bi2I9/Bi2WO6. Co‐sharing of the Bi atom can enable intimate contact and strong electron coupling between Cs3Bi2I9 and Bi2WO6, which can effectively promote the interfacial charge transfer between Cs3Bi2I9 and Bi2WO6 complying with a Z‐scheme pathway. The resulting efficient charge transfer and well‐preserved redox ability of Cs3Bi2I9/Bi2WO6 heterojunction endow it with a significant improvement of photocatalytic activity for the conversion of CO2‐to‐CO integrated with water oxidation, exhibiting a fourfold increase compared with pure Cs3Bi2I9 nanocrystals. This study paves a new avenue for the construction of efficient Z‐scheme heterojunction based on lead‐free halide perovskite, which should stimulate further passion on the development of high performance of lead‐free halide perovskite materials for photocatalytic application.

Metal Halide Perovskite Based Heterojunction Photocatalysts

“…Lu and co-workers developed a Cs 3 Bi 2 I 9 /Bi 2 WO 6 composite for CO 2 photoreduction, in which they used in situ XPS to prove the Z-scheme charge transfer. [65] Specifically, under irradiation with light, the electron binding energy of both I 3d and Cs 3d experiences negative shifts compared to those in the dark (Figure 8A and B), while, conversely, W 4f and O 1s exhibite slight shifts to higher energy (Figure 8C and D), thus indicating that the photogenerated electrons in Bi 2 WO 6 migrate to Cs 3 Bi 2 I 9 following the Z-scheme. In practice, however, observations of only a minor shift in binding energy (i.e.…”

Constructing a Cs3Sb2Br9/g‐C3N4 Hybrid for Photocatalytic Aromatic C(sp3)H Bond Activation

“…In addition to particle size control, the construction of heterogeneous photocatalysts is considered as an effective strategy to promote the separation of photogenerated charges and further enhance the catalytic performance. [ 14 ] It has been reported that CsPbBr 3 nanocrystals could be coupled with various materials, such as metal nanomaterials, [ 15 ] oxide semiconductors, [ 16,17 ] g‐C 3 N 4 , [ 18 ] and so on, to form heterostructure catalysts, and largely improved CO 2 reduction performances as compared with single CsPbBr 3 can be achieved. Similarly, it can be anticipated that the C( sp 3 )−H activation ability of lead‐free perovskite nanocrystals could be largely improved if high‐quality heterostructure catalysts are constructed.…”

Tailoring Inorganic Halide Perovskite Photocatalysts toward Carbon Dioxide Reduction

“…As introduced above, a lot of attempts have been made to replace the B‐site cation with the eco‐friendly low‐toxic or nontoxic elements, for instance, Cs 2 AgBiBr 6 and Cs 3 Bi 2 I 9 have been applied in CO 2 RR photocatalysts. [ 52,88 ] Other lead‐free materials have also been synthesized, but their potential in photocatalytic CO 2 RR has not been analyzed yet, such as M 3 Sb 2 I 9 (M = Cs and Rb) nanocrystals, CsSnI 3 , and Cs 3 Sb 2 Br 9 . [ 94–96 ] So, the efforts can be taken to find stable lead‐free candidates with higher photocatalytic performance.…”

“…Lead‐free Cs 3 Bi 2 I 9 nanocrystals on the surface of ultrathin Bi 2 WO 6 nanosheets (Cs 3 Bi 2 I 9 /Bi 2 WO 6 ) were also reported to construct a direct Z‐scheme heterojunction in Liu's report. [ 88 ] The in situ growth of Cs 3 Bi 2 I 9 /Bi 2 WO 6 successfully shared the Bi atoms, which can effectively promote the electron cloud coupling between the two composites. In the system of water as the electron source, the photocatalytic CO conversion rate was 66 μmol g −1 , under a 100 mW cm −2 light illumination.…”