Green solution synthesis of Bi19S27I3 nanostructures – engineering their morphology through polyethylene glycol and their use in the photocatalytic reduction of Cr(vi)†

Bismuth-based chalcohalides have garnered significant attention over the past five years due to their promising optoelectronic properties, and applicability in photodetection, ionizing radiation detection, photocatalysis, and solar cells. Among these compounds, Bi₁₉S₂₇I₃ stands out as a novel material with relatively unexplored synthesis and properties. In this study, we introduce a green synthesis approach for Bi₁₉S₂₇I₃ nanostructures, employing the hot injection method under mild conditions with water as the solvent. By utilizing polyethylene glycol (PEG) as a capping agent with molar proportions [PEG : Bi] 0.5 : 1, 1 : 1 and 2 : 1 and adjusting the reaction time (5 min or 270 min), we successfully controlled the morphology, yielding either round nanoparticles, nanorolls, or a combination of both. For instance, longer reaction times such as 270 min enhance the crystallinity of the material and also encourage morphology uniformity, while PEG favors a rounded morphology. Our findings underscore the significant capping effect of PEG, particularly evident in the photocatalytic activity of Bi₁₉S₂₇I₃ towards Cr(VI) reduction. Through this facile and efficient synthesis strategy, we tailored the morphology of Bi₁₉S₂₇I₃ and demonstrated its efficacy in Cr(VI) photocatalysis, achieving a remarkable 91% reduction for the nanoroll-based sample with PEG : Bi [1 : 1]. This innovative approach not only provides an environmentally friendly method for synthesizing Bi₁₉S₂₇I₃ but also highlights its potential as an effective photocatalyst for environmental remediation.