Octahedral Pt-Ni nanoparticles prepared by pulse-like hydrothermal method for oxygen reduction reaction

Abstract

Herein, the pulse temperature is provided during the nucleation period of the nanoparticles to shorten the nucleation time for Pt-based nanoparticle growth. Herein, 3-nm-sized Pt-Ni alloy octahedral catalysts were prepared by pulse-like hydrothermal method. The influence of the pulse on nucleation is demonstrated by comparing the morphology obtained from the conditions of constant temperature and pulse temperature. It has been found that pulse temperature could decrease the nucleation time, and the final morphology of the nanoparticle is different due to the different growth temperatures and times. When used in oxygen reduction reaction, the octahedron Pt-Ni exhibited a 50 mV positive shift of the half-wave potential and the mass-specific activity and area-specific activity are 5 and 7 times higher than that of commercial 40% Pt/C at 0.9 V. Through this way, kinds of multiple alloy compounds could be composed with less time in the future. Nanoparticle growth includes two parts, nucleation and growth. Herein, the pulse temperature is provided during the nucleation period to shorten the nucleation time. The 3-nm-sized Pt-Ni alloy octahedral catalysts have been prepared by temperature pulse hydrothermal method. Schematic of the nanoparticle growth via different nucleation processes: (a) at constant 170 degrees C, (b) at 170 degrees C with first 180 degrees C for 20 min, and (c) at constant 180 degrees C.