Preparation of Heterojunctions Based on Cs3Bi2Br9 Nanocrystals and g-C3N4 Nanosheets for Photocatalytic Hydrogen Evolution

Abstract

Heterojunctions based on metal halide perovskites (MHPs) are promising systems for the photocatalytic hydrogen evolution reaction (HER). In this work, we coupled Cs3Bi2Br9 nanocrystals (NCs), obtained by wet ball milling synthesis, with g-C3N4 nanosheets (NSs), produced by thermal oxidation of bulk g-C3N4, in air. These methods are reproducible, inexpensive and easy to scale up. Heterojunctions with different loadings of Cs3Bi2Br9 NCs were fully characterised and tested for the HER. A relevant improvement of H2 production with respect to pristine carbon nitride was achieved at low NCs levels reaching values up to about 4600 µmol g−1 h−1. This work aims to provide insights into the synthesis of inexpensive and high-performing heterojunctions using MHP for photocatalytic applications.

Cs3Bi2Br9/g-C3N4 Direct Z-Scheme Heterojunction for Enhanced Photocatalytic Reduction of CO2 to CO

“…It was observed that bulk g-C 3 N 4 and Cs 3 Bi 2 Br 9 absorbed similar wavelengths of light with absorption edges at around 463 and 493 nm, respectively. Measuring the absorbance of the composites in comparison to the pure semiconductors showed a higher absorbance between 300 and 450 nm with a slight redshift for the composites . In particular, the 40 wt % Cs 3 Bi 2 Br 9 /g-C 3 N 4 composite demonstrated the highest light absorbance, suggesting that this composition forms a heterostructure where the two semiconductors complement each other in terms of light harvesting ability, which is important for the photogeneration of charges.…”

“…While possessing an alignment in band energetics and complementary optoelectronic properties, research on Cs 3 Bi 2 Br 9 /g-C 3 N 4 composites has been focused on H 2 evolution and oxidation reactions. − To date, little research has explored photocatalytic CO 2 reduction in the gas-phase without the use of hole scavengers. In this work, we successfully synthesized a direct Z-scheme heterojunction between Cs 3 Bi 2 Br 9 and bulk g-C 3 N 4 using a straightforward antisolvent crystallization method.…”

Band gap tuning through cation and halide alloying in mechanochemically synthesized Cs3(Sb1−xBix)2Br9 and Cs3Sb2(I1−xBrx)9 solid solutions

“…Among these systems, bismuth- and antimony-based perovskite derivatives of general formula Cs 3 M 2 X 9 (M = Bi, Sb; X = Br, I) have shown strong technological potential, in particular in the area of photocatalysis (both for solar fuel generation and organic synthesis) and photodetection. 20–36…”

“…Among these systems, bismuth-and antimony-based perovskite derivatives of general formula Cs 3 M 2 X 9 (M = Bi, Sb; X = Br, I) have shown strong technological potential, in particular in the area of photocatalysis (both for solar fuel generation and organic synthesis) and photodetection. [20][21][22][23][24][25][26][27][28][29][30][31][32][33][34][35][36] Bismuth-based defect-ordered perovskites have been an object of more intense studies compared to the corresponding Sb systems, notwithstanding their appealing optoelectronic properties such as high carrier mobility, low trap density, and long diffusion length. As a matter of fact, Cs 3 Sb 2 Br 9 millimetersized single crystals and nanoflakes have been applied in the fabrication of photodetectors with excellent performance in terms of responsivity and detectvity.…”

Band Gap Tuning Through Cation and Halide Alloying in Mechanochemical Synthesized Cs3(Sb1-xBix)2Br9 and Cs3Sb2(I1-xBrx)9 Solid Solutions

“…Among these systems, bismuth-and antimony-based perovskite derivatives of general formula Cs3M2X9 (M=Bi, Sb; X=Br, I) have shown a strong technological potential in particular in the area of photocatalysis (both for solar fuel generation and organic synthesis) and photodetection. [20][21][22][23][24][25][26][27][28][29][30][31][32][33][34][35][36] Bismuth-based defect-ordered perovskites have been object of more intense studies with respect to the corresponding Sb systems, notwithstanding their appealing optoelectronic properties such as high carrier mobility, low trap density, and long diffusion length. As a matter of fact, Cs3Sb2Br9 millimeter-sized single crystals and nanoflakes have been applied in the fabrication of photodetectors with excellent performance in terms of responsivity and detectvity.…”