Research database

STRATEGY aims at demonstrating a radically new approach to design catalyst layers (CL) for energy devices as fuel cells, based on Laser-Induced Graphene with Hierarchical pore structure (H-LIG) and controlled composition obtained under ambient conditions from electrospun-1D nanofibers (NFs) of synthetic polymers after alkaline treatment. During laser processing, the conversion of NFs into graphene will induce the crystallization of metal-oxide (MO) nano-catalysts (NCs). This project will prove the possibility to control NCs nucleation at the surface of H-LIG NFs by laser writing. The exploitation of surface-sensitive characterization techniques applied at nano- and mesoscale based on electron microscopy and x-ray scattering measurements coupled with the non-destructive tomography for 3D reconstruction of the porous structure and with in-operando experiments during the catalytic process will guarantee the control of all the process parameters. Studies will show that NFs made of N-rich polymers mixed with MO precursors enable the creation of H-LIG with enhanced durability, stability and catalytic activity toward the oxygen reduction reaction (ORR). The new method is based on the rational combination of laser writing, activation, and electrospinning to obtain a 3D LIG characterized by a hierarchical structure overpassing the properties of materials obtained by the separate use of each process. H-LIG combines all the merits of graphene-based materials to the hierarchical porosity due to the micropores of LIG, the mesopores of the alkali-induced activation and the macropores of the 1D-NFs by electrospinning. In this radically new process, electrospun-NFs hold great promise as the ideal nanoscale building blocks to control and tune the degree of interconnection in the H-LIG and thus enable control and modulation of hierarchical porosity and composition. Solutions of synthetic polymers with high carbonization yield will be optimized and investigated in the presence of metal-organic precursors, such as manganese oxide, to obtain CLs with optimal electrocatalytic behavior toward the ORR. As-electrospun NFs will be treated in alkaline solutions, thus enabling conversion in LIG of ALL polymers by CO2 laser in ambient conditions (patent pending), allowing the conjunct activation of graphene during its formation. With this radically new approach, STRATEGY allows LIG in ambient conditions from polymers such as polyacrylonitrile and polyvinylidene fluoride traditionally carbonized in a controlled atmosphere only. Opening laser processing to nanostructured polymers of this kind offers new opportunities to combine tunable porosity to spontaneous doping in LIG, adding catalytic properties that can be of extreme interest for energy applications. STRATEGY project will investigate the new process deeply to identify the parameters governing porosity features and relate them to the chemical, physical and catalytic properties to develop innovative H-LIG CLs.