RECYCLED Pt-ELECTROCATALYST SUPPORTED ON POSIDONIA OCEANICA BIOCARBON FOR ENVIROMENTAL-FRIENDLY OXYGEN REDUCTION REACTION

Biomass-derived carbon materials are emerging as potential alternatives to reduce the production cost and environmental impact of electrocatalyst production. This research highlights the innovative use of biochar derived from residues of a sea-plant as a renewable resource for fabricating recycled metal electrocatalysts, addressing both the environmental issue of waste disposal and the demand for recycling of critical materials. Posidonia oceanica is a sea-plant of the Mediterranean area that forms large beds along the coasts. The dead leaves accumulate in large amounts on the coasts and it is estimated that at the end of the vegetative period, a great amount of dead fragments (∼10-20 t per hectare of Posidonia oceanica meadow) are formed and that it is deposited on the shorelines by the wave action [1]. Recently authors demonstrated that the pyrolysis of sea-plants is a promising way to obtain high-surface area bio-carbons [1]. By pyrolyzing dead Posidonia Oceanica leaves at 400°C and subsequently acid activating (H3PO4) the derived biochar, a porous bio-carbon was obtained. Successively, the activated biocarbon was functionalized with recycled critical material, successfully producing a catalyst with notable characteristics. In particular, a “homemade” 30 wt.% Pt electrocatalyst supported on carbon was prepared by impregnation of a Pt-sulfite complex increasing the electronic conductivity of the sample. Finally, after the decomposition of the sulfite by hydrogen peroxide addition, a carbothermal reduction at 600°C in a helium atmosphere was carried out to obtain the metallic Pt/C catalyst. X-ray Diffraction (XRD), Scanning Transmission Electron Microscopy-Energy dispersive X-ray spectroscopy (S/TEM-EDX), and X-ray Photoelectron Spectroscopy (XPS) were used to characterize the structure, morphology, and surface characteristics of the catalyst. For the electrochemical measurements, the rotating disc electrode (RDE) technique under acid and alkaline conditions was employed to investigate the oxygen reduction activity. This study is significant not only for its innovative approach to biomass/waste utilization but also for pioneering the exploration of waste-derived materials in fuel cell applications, thereby paving the way for future research in sustainable energy technologies. Overall, the findings underscore the potential of transforming environmental challenges into opportunities for developing efficient and eco- friendly energy solutions.