Elettra | MCX Thermal response of graphene oxide and silver-functionalized graphene oxide loaded with perfluorinated compounds Graphene oxide (GO) is a nanomaterial that has attracted great interest due to its large surface area, tunable chemical functionality, and robust mechanical properties. These characteristics make GO a highly versatile platform for the development of new materials with applications in environmental remediation, sensing, and catalysis. A promising approach to enhance GO’s performance is to combine it with silver nanoparticles (Ag NPs), resulting in a hybrid material (AgGO) that merges the structural adaptability of GO with the well-known catalytic properties of silver. However, a key question remains open: how do these GO-based hybrid materials behave when exposed to elevated temperatures, especially in the presence of environmental pollutants? To explore this, we carried out a detailed investigation of the thermal response of GO and its silver-functionalized form (AgGO) when loaded with two persistent pollutants: perfluorooctanoic acid (PFOA) and perfluorooctane sulfonate (PFOS). These substances belong to the family of PFAS, which are often referred to as “forever chemicals” due to their extreme resistance to degradation. They are frequently used in industrial and consumer products, and are of increasing environmental and health concern due to their long-term persistence. The experiments were carried out at the MCX beamline of Elettra Sincrotrone Trieste in Italy, using a powerful technique known as in situ time-resolved synchrotron x-ray powder diffraction (SRXRPD). This method allowed us to follow, in real time, how the structure of the materials evolved as they were gradually heated to 400°C. One of the most revealing findings concerned the interlayer spacing between GO sheets see Figs. 1 (a, b). Initially, the hydrated GO layers were separated by about 0.86 nanometers. As the temperature increased, this spacing shrank- a clear sign that oxygencontaining groups were lost-, and the material was undergoing chemical reduction. However in presence of PFOA and PFOS, this contraction occurred more gradually as visible in Figs. 1 (c,d). The layered structure of the GO–AgGO/ PFOA–PFOS system remained more stable when exposed to heat than similar samples without the fluorinated compounds. This indicates that PFOA and PFOS, despite being pollutants themselves, may play a stabilizing role in the thermal behavior of GO and AgGO. The data also showed changes in the chemical state of silver, that were affected by both heating and interaction with the perfluorinated molecules. Taken together, these results suggest a complex dynamic involving the layered structure of GO, silver nanoparticles, and PFAS compounds under thermal conditions. Why does this matter? Understanding how such hybrid materials respond to heat is crucial for the development of functional nanomaterials that can be used in real-world environments, where exposure to heat and pollutants is common. Applications such as air and water filtration, chemical sensors, and energy devices require materials that are not only effective but also thermally stable and durable. The use of synchrotron radiation at Elettra was crucial to these findings. The high brightness and time resolution of the MCX beamline allowed us to observe subtle changes in structure and composition as they occurred. This provides a rare insight into thermal processes at the atomic level that are normally difficult to capture. In summary, this study sheds light on how GO-based hybrid materials behave when exposed to heat in the presence of persistent pollutants such as PFOA and PFOS. It demonstrates that fluorinated compounds can affect both the reduction kinetics of GO and the redox chemistry of silver. These findings provide the basis for engineering more resistant and environmentally friendly nanomaterials, that can impact advanced technologies. Elettra Highlights 2024–2025 20
RkJQdWJsaXNoZXIy MjQ4NzI=