Synthesis And Catalytic Performance Research On Heteropoly Acid-Modified Platinum Catalyst

Fuel cells are generally considered as a efficient, clean and silent technology that can produce electricity and heat from hydrogen because hydrogen is an efficient fuel and environmentally clean, but one of the important challenges for PEMFC commercialization is the preparation of active, robust and low-cost catalysts. The synthesis and processing of heteropolyacids-modified platinum catalyst system, as described in this article, serves as an attractive way to address this challenge.This article will heteropoly acid doped by platinum core-shell type catalyst in the preparation of several different kinds of catalyst, the main work is as follows:1. In this work, we immobilized the negatively charged HPW on Ag@Pt/MWCNTs nanoparticles attached with the positively charged functional groups of chitosan by the electrostatic interaction to get HPW-modified Ag@Pt/MWCNTs electrocatalysts. Electrochemical investigation results indicated that HPW could ameliorate electrocatalytic activity of the catalyst and the catalyst with a HPW content of 25% had the most excellent electrocatalytic activity of all catalysts, an electrochemically active area of 83.62 m2·g-1,which is 59% higher than that of Pt/C(JM) (56.23 m2·g-1), and the onset potentials positively shift 44 mV compared with Pt/C(JM).2. H3PMo12O40(PMo) was prepared by coventional method at room temperature. X-ray powder diffraction (XRD) and Fourier Transform Infrared Spectrometer (FTIR) prove the PMo exists in the form of Keggin unit. Electrochemical investigation results indicated that PMo could ameliorate electrocatalytic activity of the catalyst and the catalyst with a PMo content of 15% had the most excellent electrocatalytic activity of all catalysts, an electrochemically active area of 96.25 m2·g-1, which is 83% higher than that of Pt/C (56.23 m2·g-1), and the onset potentials positively shift 53 mV compared with Pt/C(JM). The number of electrons transferred obtained by the Koutecky-Levich equation is 3.95, indacating that the ORR follows a 4e" pathway of O2 to H2O on Ag@Pt/MWCNT-15%PMo.3. Molybdovanadophosphoric acids (PMo12-nVn (n=1,2,3)) was prepared by coventional method at room temperature. X-ray powder diffraction (XRD) and Fourier Transform Infrared Spectrometer (FTIR) prove the PMo12-nVn (n=1,2,3) exists in the form of Keggin unit. The largest electrochemical active area Ag@Pt/MWCNTs-20% PMo,,V is 84.76 m2·g-1, Ag@Pt/MWCNTs-20% PMo10V2 is 97.86 m2·g-1, Ag@Pt/MWCNTs-20% PMo9V3 is 79.25 m2·g-1.