Recovery of Pd, Pt, and Rh metals from catalyti̇c converters, synthesi̇s of fullerene-cored yolk-shell nanoparti̇cles, and measurement of thei̇r hydrogen storage capaci̇ti̇es

Palladium, platinum, and rhodium, metals used in hydrogen storage technologies, are costly and limited resources. These metals are widely used in the automotive industry in catalytic converters to transform exhaust gases into less harmful compounds. However, over time, these parts lose their functionality, are replaced, and become waste. Depending on the vehicle, a catalytic converter contains between 1 and 5.5 grams of Pd, Pt, and Rh; since these precious metals are not recovered in our country, they are sold abroad at low prices. Within the scope of this thesis, an effective hydrometallurgical method for the recovery of Platinum Group Metals (PGMs) from waste catalytic converters was successfully implemented, achieving a high leaching efficiency of 94.3%, particularly for Platinum (Pt). The recovered metals were converted into auto-reducible complexes for use in advanced synthesis stages. Using these complexes, single and double-layered yolk-shell type nanomaterials, consisting of a fullerene (C₆₀) core and a metal shell, were synthesized. The morphological, structural, and chemical properties of the synthesized nanostructures were examined in detail using advanced characterization techniques such as XRD, SEM-EDX, HR-TEM, and BET. The hydrogen storage properties of the synthesized materials were analyzed with a TPD/TPR instrument. The results of the analysis determined that the single-layered C₆₀@Pt structure exhibited the superior performance among the tested materials, providing the highest hydrogen desorption signal in the range of approximately 100 200°C. The lowest performance, however, was observed in the C₆₀@Pd sample. This study demonstrates that high-value-added nanomaterials can be produced through the valorization of waste and that these materials can be effectively used in hydrogen storage, a clean energy technology.