The interaction of δ-CsPbI3 and CsPbBr3 nanostructures with soil extracts

Cesium lead halide nanostructures (CsPbX3, where X = I or Br) are increasingly popular for solar cell applications, but their waste management remains underdeveloped, raising concerns about their potential accumulation in soil. This study investigates the environmental stability of CsPbI3 and CsPbBr3 nanostructures synthesized at different temperatures. Phenol was chosen as a model pollutant for the photocatalytic activity investigations, and the samples at 130 °C showed the ideal balance in terms of stability and activity. Therefore, these samples were then interacted with acidic and basic artificial soil extracts, thus representing the soil solution under different environmental conditions. X-ray diffraction (XRD), scanning electron microscopy (SEM), X-ray fluorescence (XRF), diffuse reflectance spectroscopy (DRS), and infrared (IR) spectroscopy were used to assess the material changes, while Pb leaching after interaction with soil extracts was measured by inductively coupled plasma mass spectrometry (ICP-MS). CsPbI3 exposed to acidic extracts leached Pb, I, and Cs (as CsI), while PbI2 stayed insoluble. Alkaline extracts caused minimal Pb leaching, indicating recrystallization, and CsPbBr3 showed similar behavior. ICP-MS measurements showed that Pb concentrations were higher in acidic soil extracts than in basic ones. Pb concentrations increased with longer exposure. CsPbI3 showed lower Pb concentrations than CsPbBr3, suggesting that CsPbI3 is more stable. These findings emphasize the stabilization strategies-such as chemical modifications, protective surface coatings, or composite material designs-to improve the durability of CsPbX3 nanomaterials under realistic environmental conditions. Without such advancements, the large-scale deployment of these perovskites and nanostructures could pose significant environmental risks.