(Digital Presentation) Synthesis and Promoting Activity of Gd2O3 for Methanol Electro-Oxidation on Pt/C

Abstract

One of the challenges in electrocatalysis is to design either an efficient non-noble electrocatalyst or improve the electrocatalytic activity of Pt/C by incorporating promoters such as metal oxides, carbides and nitrides. Rare earth metal oxides such as CeO2 have been explored to promote methanol electro-oxidation on Pt/C electrocatalyst. It has been noted that the synthesis method has profound effect on the physiochemical and in turn electrochemical properties of metal oxide promoted Pt/C electrocatalysts. This concept is tested on Gd2O3 promoted Pt/C. Gd2O3 is prepared by precipitation (GdO-PC) method and polymer assisted method (GdO-PL). The oxygen storage capacity (OSC) of this oxide is correlated with the electrochemical activity of Gd2O3-Pt/C. GdO-PC has higher OSC and can release surface oxygen much easier as compared to GdO-PL for methanol electro-oxidation on Pt. The Gd2O3-Pt/C catalysts are prepared with Gd2O3, Vulcan carbon and Pt-salt (equivalent to 20 wt% Pt) using microwave assisted polyol reflux method. The electrocatalytic activity of Gd2O3-Pt/C towards methanol oxidation has been carried out by cyclic voltammetry, CO stripping experiments, chronopotentiometry, and chronoamperometry methods in acidic media. The measurements show that Pt-GdO-PC/C performs better than Pt-(GdO-PL)/C) and commercial Pt/C. This indicates that the synthesis route of Gd2O3 particles is crucial for promoting methanol electro-oxidation. The first principle calculations show that there is a charge transfer from Gd2O3 to Pt. (GdO-PC). It is concluded that higher OSC and charge transfer from Gd2O3 to Pt work in tandem to weaken the Pt-CO bond and oxidise CO to CO2, thus reducing the CO poisoning and enhancing the activity of the oxide promoted electrocatalyst. Figure 1