La₂O₃ Promoted Pd/rGO Electro-catalysts for Formic Acid Oxidation.

Area of Science:

• Electrochemistry
• Materials Science
• Catalysis

Background:

• Direct formic acid fuel cells (DFAFCs) require highly active, stable, and CO-poisoning resistant palladium (Pd) electro-catalysts for anode applications.
• Achieving uniform dispersion of Pd nanoparticles on supports and ensuring efficient electron transfer are key challenges in catalyst development.

Purpose of the Study:

• To investigate the effect of lanthanum (La) and La-oxides on the performance of Pd nanoparticles supported on reduced graphene oxide (rGO) for formic acid electro-oxidation.
• To synthesize and characterize novel Pd-La/rGO electro-catalysts with varying molar ratios.

Main Methods:

• Synthesis of Pd-La/rGO electro-catalysts with different Pd-La molar ratios.
• Characterization using Powder X-ray Diffraction (PXRD), X-ray Photoelectron Spectroscopy (XPS), Transmission Electron Microscopy (TEM), Fourier-Transform Infrared Spectroscopy (FTIR), and Raman spectroscopy.
• Electrochemical testing as anode materials in direct formic acid fuel cells.

Main Results:

• Lanthanum species significantly enhance the activity and stability of Pd catalysts for formic acid electro-oxidation.
• The optimal catalyst, Pd₃₀La₇₀/rGO, exhibited a mass specific activity of 986.42 A/g, which is 2.18 times higher than Pd/rGO and 16 times higher than Pd/C.
• High activity and stability are attributed to uniform Pd nanoparticle dispersion on the rGO support, facilitated by La species.

Conclusions:

• Lanthanum addition is a promising strategy to improve Pd-based electro-catalysts for DFAFCs.
• The La species aid in catalyst particle dispersion and facilitate electron transfer, leading to enhanced electrochemical performance.
• The Pd-La molar ratio is critical, with Pd₃₀La₇₀/rGO showing superior catalytic properties.