PtGd/Gd_2O_3 alloy/metal oxide composite catalyst for methanol oxidation reaction

摘要

Pt-transition metal alloys are frequently used to improve the catalytic activity for methanol oxidation reaction. However, the severe dealloying strongly limits the applications of Ptbased alloy in fuel cells. Recently, Pt-rare earth metal alloys are considered to be the promising catalysts for electrocatalytic application in fuel cells. Metal oxide as the cocatalytic component of composite catalyst, is also applied to regulate the electronic structure and strengthen resistance to CO poisoning. In this work, we utilized hydrogen reduction method to prepare PtGd/Gd2O3 composite catalyst. X-ray diffraction result illustrates that both Gd2O3 and PtGd alloy co-exist in PtGd/Gd2O3 material. X-ray photoelectron spectroscopy data confirms that the main valence states of Pt and Gd are metal form in the PtGd/Gd2O3 catalyst and emerges obvious transfer of element binding energy. Transmission electron microscopy data presents that composite PtGd/Gd2O3 particles are uniformly dispersed on the carbon power with a typical core-shell structure. And upon the increase of Gd precursor in reduction process, the metal oxide layer becomes more thicker for PtGd/Gd2O3 composite material. Because of the synergistic contributions given by the Pt eGd bimetals and alloy-metal oxide between PtGd alloy and Gd2O3 oxide, the PtGd/Gd2O3 composite catalysts exhibit superior catalytic performance toward methanol oxidation reaction. Specifically, the mass activity of Pt1Gd1/Gd2O3 is about 1.9 times that of commercial Pt/C; besides this, the optimal specific activity of Pt1Gd2/Gd2O3 is almost 4 times that of commercial Pt/C. More importantly, the Pt1Gd1/Gd2O3 emerged a 20.9% degradation after 8000 cycles test, while commercial Pt/C showed a 61.7% degradation. And this work provides an important insight for rare earth elements investigation on the electrocatalysis application in fuel cells. (C) 2021 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.