Synthesis of applications pd-doped carbon-based catalysts for direct hydrazine fuel cells

Fuel cells are highly efficient and environmentally friendly systems that directly convert chemical energy into electrical energy. In this thesis, palladium (Pd)-based anode electrodes were developed as cost-effective alternatives to platinum (Pt)-based catalysts for hydrazine oxidation. Five Pd-based catalysts (1A, 1B, 2A, 2B-1, and 2B-2) were synthesized using various methods with waste coal tar pitch (rCTP), glass fiber (GF), and couch grass (TT) as support materials. The structural and morphological properties of the synthesized materials were characterized using scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDX), and X-ray diffraction (XRD). Their electrochemical performances were evaluated through cyclic voltammetry (CV), chronoamperometry (CA), and electrochemical impedance spectroscopy (EIS). As a result of the electrochemical characterizations, the Pd-CTP/GF electrode exhibited the highest performance, achieving a maximum current density of approximately 13 mA/cm² within a constant current density range of 3.5–4.0 mA/cm². EIS measurements revealed a low charge transfer resistance, and voltammetric analysis confirmed that hydrazine oxidation follows a diffusion-controlled mechanism. Fuel cell performance tests demonstrated that the 2B-2 catalyst reached a maximum current density of 80 mA/cm² at 10 mL/min hydrazine and 500 mL/min oxygen flow rates. These results indicate that the synthesized 2B-2 catalyst is a promising anode material for direct hydrazine fuel cells (DHFC) due to its high conductivity and low charge transfer resistance.