Self-assembly of HPW on Pt/C nanoparticles with enhanced electrocatalysis activity for fuel cell applications
We report here a novel method to immobilize water soluble tungstophosphoric acid (H3PW12O40, HPW) on Pt/C nanoparticles via the electrostatic interaction between the negatively charged HPW and the positively charged functional groups of chitosan which has been attached to Pt/C nanoparticles to provide positively charged sites for the self-assembly of HPW. The HPW assembled Pt/C catalysts (donated as Pt/C-chitosan-HPW) were characterized by XRD, FTIR, TGA, zeta potential, and X-ray photoelectron spectroscopy (XPS). The results indicate that HPW assembled on chitosan-functionalized Pt/C is very stable and Pt/C-chitosan-HPW catalyst has a higher utilization efficiency as compared to that of pristine Pt/C catalyst. Electrochemical activity of Pt/C-chitosan-HPW catalysts for methanol oxidation and oxygen reduction reaction (ORR) is significantly higher than that of Pt/C catalysts without assembled HPW. The enhanced electrocatalytic activities of HPW assembled Pt/C catalysts are most likely due to the synergistic effect between assembled HPW and Pt/C nanoparticles and the presence of HPW leads to a downward shift in the d-band center of Pt catalyst and facilitates the oxidative removal of COads poisoning species for methanol oxidation and desorption of Oads species for ORR on Pt catalysts.
Graphical abstractFigure optionsDownload full-size imageDownload as PowerPoint slideResearch highlights► Water-soluble HPW was immobilized on the surface of Pt/C nanoparticles by self-assemble technique. ► The assembled HPW has shown high stability on Pt/C. ► The HPW assembled Pt/C catalyst has shown higher catalyst utilization efficiency and electrocatalytic activities than pristine Pt/C.
Journal: Applied Catalysis B: Environmental - Volume 103, Issues 3–4, 5 April 2011, Pages 311–317