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.