Electrodeposited Pd Nanoparticles onto Fe3O4-S-rGO for Methanol Electro-oxidation

A series of Pd/Fe₃O₄@S-rGO was synthesized under various deposition times of Pd and their catalytic activity was investigated in alkaline media via chronoamperometry (CA), cyclic voltammetry (CVs), and electrochemical impedance spectroscopy (EIS) for the methanol oxidation reaction. For the S source, sodium dodecylbenzene sulfonate (SDBS) was used to obtain ultrafine Fe₃O₄ particles and enhance the graphene layer properties. Through the characterization measurements, it is concluded that Pd was deposited successfully onto Fe₃O₄@S-rGO (S and Fe₃O₄ dual-doped reduced graphene oxide) with nanoscale cubic lattice nanostructure. In the presence of Fe₃O₄, the band gap of Pd₄₅₀/ITO decreased from 3.46 to 1.74 eV. The band gap of fabricated catalyzes changed with the deposition time of Pd. In addition, the synergistic effect between Pd and Fe₃O₄ enhances the catalytic activity of the electrode toward methanol oxidation when compared bulk Pd electrode. The Pd₄₅₀/Fe₃O₄@S-rGO electrocatalyst showed a current density of 22.3 mA cm⁻² at a scan rate of 30 mV s⁻¹ with remarkable long-term stability in 0.5 M methanol in 1 M NaOH. This value is 2.2 times higher than the Pt/C (10 mAcm⁻²) catalyst under the same conditions. With modifying Fe₃O₄ the Tafel slope of Pd₄₅₀/ITO decreased from 180 to 118 mVdec⁻¹.

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