In situ growth of Cs3Bi2Br9 on ultrathin BiVO4 nanosheets to fabricate heterojunction intimate interfaces for enhancing photocatalytic activity

Abstract

Lead-free halide perovskites have emerged as a potential green photocatalyst with wide-ranging applications in environmental remediation and energy conversion. However, undesirable charge recombination and insufficient visible light absorption of pure halide perovskites would limit the photocatalytic performance. Herein, an intriguing perovskite-based Cs₃Bi₂Br₉/BiVO₄ S-scheme heterojunction was fabricated for the first time by in situ growth of Cs₃Bi₂Br₉ on BiVO₄ nanosheets (BiVO₄ NSs). The degradation results of Sudan red III under visible light showed that the optimized 5% Cs₃Bi₂Br₉/BiVO₄ achieved a 99.2% degradation rate within 40 min, which was ∼2.37 times higher than pure Cs₃Bi₂Br₉ and ∼106 times higher than BiVO₄, respectively. The effective removal of organic dyes is mainly attributed to the extended visible light absorption range, the charge transfer accelerated by the built-in electric field, and the abundance of reactive radicals (˙O₂⁻) after the formation of the intimate interface of the Cs₃Bi₂Br₉/BiVO₄ S-scheme heterojunction. In addition, six consecutive cycles of photocatalytic experiments and stability tests demonstrated excellent photocatalytic properties of Cs₃Bi₂Br₉/BiVO₄. This work provides useful guidance for the development and construction of efficient lead-free perovskite-based heterojunction photocatalysts.