Tailoring heterojunctions in CsPbBrxCl3-x - MoS2 composites for efficient photocatalysis and hydrogen evolution

Abstract

We demonstrate appropriate tuning of heterojunctions in CsPbBrxCl3-x – MoS2 composites (where x=0,1,2,3) by controlled regulation of the halide stoichiometry in the perovskite. A thorough optimization procedure determined the most effective photocatalyst, considering the pristine MoS2, perovskites with varying halide ratios, various physical mixing ratios of the two, and in-situ synthesized composite ratios of CsPbBrxCl3-x and MoS2 (2:1, 1.5:1, 1:1, 1:1.5, 1:2). Under two hours of exposure to visible light, a remarkable photocatalytic performance of CsPbBrCl2:MoS2 with a 1:2 ratio was observed, removing 98% of the methylene blue (MB) dye. Notably, only the CsPbBrCl2 and MoS2 composite demonstrated higher efficiencies since it resulted in a n-n type II heterojunction. Additionally, the CsPbBrCl2:MoS2 composite exhibits the highest reaction rate constant, fifteen times higher than the pristine perovskite. Reusability assessment of this combination revealed sustained activity of 87% for up to 5 cycles. The hydrogen evolution reaction investigations were carried out using the optimized CsPbBrCl2:MoS2 composite, which yielded 265 times more hydrogen than pristine CsPbBrCl2. The Faradaic efficiency for 1:2 CsPbBrCl2:MoS2 was found to be 96.61%. Our results offer crucial perspectives on optimizing perovskite-MoS2 composites and demonstrate their utility in sustainable applications, including water treatment, renewable energy harvesting, and environmental remediation.