A Pd/PW12/RGO Composite Catalyst Prepared by Electro-Codeposition for Formic Acid Electro-Oxidation

A highly active Pd based catalyst for direct formic acid fuel cells (DFAFCs), Pd/Na3PW12O40 (PW12)/reduced graphene oxide (RGO), was prepared by a facile and green preparation strategy based on electrochemical-codeposition. The composite was investigated by SEM, TEM, XPS, Raman spectroscopy and XRD. The GO and PdCl42− can be reduced simultaneously and the mass of Pd is measured to be ca. 18.7 μg for Pd/PW12/RGO composite. The PW12 can facilitate the deposition of more uniform and smaller Pd nanoparticles. Notably, the Pd/PW12/RGO catalyst exhibits higher specific activity ranging from 0.15 V to 0.30 V toward formic acid electro-oxidation as compared with the Pd/RGO and Pd/C catalyst. The specific activity for Pd/PW12/RGO catalyst (5.98 mA cm−2Pd at 0.2 V vs. Ag/AgCl) is enhanced by a factor of 2.4 in comparison with Pd/RGO catalyst (2.49 mA cm−2Pd at 0.2 V vs. Ag/AgCl). Moreover, Pd/PW12/RGO catalyst displays an improved stability for formic acid electro-oxidation and a better tolerance toward CO poisoning than Pd/RGO and Pd/C catalyst. The enhanced performance of Pd/PW12/RGO catalyst can be contributed to the synergistic effect of better dispersion of Pd nanoparticles, and high protonic conductivity and superior oxidation power of PW12.