Preparation And Electrochemical Properties Of Pt-Ni-P Ternary Composite Nanoparticles For Methanol Oxidation

Direct methanol fuel cells (DMFCs) are regarded as an ideal candidate forstationary and mobile power generation due to their high energy conversion efficiency,low environmental impacts, simple structure, easy transportion, and high energy density.Up to now, precious metals Pt and their alloys is still the most widely used anodecatalyst in DMFCs. However, the current major limitations are the limited reserves of Ptresources, poor durability, high cost, low Pt utilization and the CO intermediatesproduced in the methanol oxidation process strongly adsorbed on the Pt surface to froma Pt-CO, and other factor of electocatalyst. Therefore, how to reduce the amount ofprecious metals Pt, enhance its catalytic activity and stability, and looking for moreexcellent catalytic performance anode catalytic alternative materials, has been a hotresearch in DMFCs.Firstly, we report a novel strategy to prepare Pt-Ni-P ternary alloy catalyst by usingpulse electrodeposition-displacement method. The stability and activity of Pt-Ni-P/Tiand Pt-Ni/Ti electrodes were evaluated by scanning electron microscopy (SEM), cyclicvoltammetry (CV), linear sweep (LSV), and chronoamperometry (CA). The resultsshow that the Pt-Ni-P nanoparticles exhibits higher methanol oxidation catalytic activityand stability in acidic and alkaline solution as compared with Pt-Ni/Ti electrode. Theincreased catalytic performance can be attributed to the P-doping that can effectivelyenhance the methanol oxidation catalytic activity, stability and CO-tolerance.Secondly, we prepared TiO2nanotubes (TNTs) support by anodization method. Theas-prepared TNTs were then used as the support for Ni-P electrodeposition anddisplacement of Pt-Ni-P nanoparticles, and then the methanol electro-oxidation wasinvestigated on such an electrode under illumination. A comparative study shows thatthe performance and CO-toleranc of the Pt-Ni-P/TNTs/Ti electrode for methanolelectro-oxidation is remarkably enhanced under illumination. The enhanced catalyticactivity is attributed to the larger specific surface area, effective scattering andabsorption of light and less detrimental grain boundaries, which can therefore generatemore electron-hole parirs and effectively lessen the electron-hole recombining underillumination. Therefore TNT can more effectively produce strong oxidingoxygen-containing species·OH from water for removing COadsunder illumination.