Carbon Dots Modified Graphite as Novel Support Material for Low Palladium (Pd) Loading Direct Ethanol Fuel Cell Catalyst

Direct ethanol fuel cells (DEFCs) provide a clean, sustainable substitute for fossil fuels. In DEFCs, noble metal nanoparticles on carbon support are employed as electrocatalysts for ethanol oxidation reaction (EOR). However, the reaction is significantly more complex. The kinetically sluggish EOR process confines its practical feasibility. As a result, modifications to the carbon support are required to reduce metal loading while increasing practicability. This study uses oleic acid as an organic medium to create carbon dots (CDs) with exceptional thermal stability. CDs act as supports for the palladium, which reduces Pd (II) to Pd (0). Electronic spectra confirm the formation and chemical composition of the catalyst. Physically placed on a graphite substrate, the synthesized CDs and Pd-dopped CDs were studied as anode materials for the EOR. Different electrocatalysts were studied by varying compositions of Pd with fixed CDs loading. It is found that the C-CDsPd0.51 catalyst shows lower EOR onset potential, moderate current density of 0.520 mA/cm2 (mass specific current density: 2.3 mA mg-1 catalyst), lower charge transfer resistance (~360 ohm), and good stability over a long period. Depending upon the electrochemical performance, optimum Pd-loading was also determined. Hence, C-CDsPd can be considered a suitable electrocatalyst material for DEFCs.