Indium-based quantum dots trapped in solid-state matrices: a one-pot synthesis, thermoresponsive properties, and enhanced micropollutant removal

Indium-based quantum dots (QDs), such as copper indium disulfide and zinc copper indium sulfide, have been the center of research for decades due to their low toxicity and unique photophysical properties. In contrast, versatile indium-based materials like In₂S₃ and ZnIn₂S₄ have been rarely studied in their QD form because of the challenges in their synthesis and used in solid-state material based applications because of their colloidal nature. In this study, a one-pot single-step method to synthesize In₂S₃, ZnIn₂S₄, and Cu-doped ZnIn₂S₄ QDs trapped in insoluble solid-state oleic acid matrices was developed. The QDs in solid-state matrices exhibited bright orange colored fluorescence with controllable emission properties achieved by altering the chemical composition. Among these QDs, the ZnIn₂S₄ QDs displayed thermo-responsive properties. As the temperature increased, the fluorescence intensity of ZnIn₂S₄ QDs decreased. In addition, all QDs demonstrated high removal efficiency for micropollutants in the aqueous medium, especially against cationic organic dyes. This study represents one of the first attempts at the direct development of QDs trapped in insoluble solid-state matrices. The QDs in solid-state matrices hold promise for applications in thermal sensors and studies related to the micropollutant removal.