Activated ZrC Promotes the Methanol Electro-oxidation Activity and Enhances Poison Tolerance of Pt Nanoparticles in Acidic Medium

Metal carbides which mimic Pt metal are good promoters for electrocatalytic reactions. Here we report the promoting activity of activated ZrC (a-ZrC) towards methanol electrooxidation reaction. Thea-ZrC samples are prepared from commercial ZrC by chemical activation at two different temperatures (600 and 800 degrees C) using Na(2)CO(3)as an activating reagent. The BET surface area of the commercial ZrC sample is 1 m(2) g(-1)which has been increased to 82 m(2) g(-1)and 134 m(2) g(-1)by chemical activation at 600 and 800 degrees C, respectively. In order to study the promoting activity of the activated ZrC samples in direct methanol fuel cell (DMFC),a-ZrC supported Pt/Vulcan carbon (XC) is synthesized through conventional polyol reflux method. The electrocatalytic activities of Pt/a-ZrC800-XC, Pt/a-ZrC600-XC, Pt/ZrC-XC and Pt/XC electrocatalysts have been studied towards methanol electrooxidation reaction in an acidic media. The triple interface between Pt, activated ZrC and Vulcan carbon (Vulcan XC-72R) reduces the adsorption energies, facilitating fast transport and short diffusion paths for electroactive species, which makes the Pt/a-ZrC800-XC catalyst promising for DMFC applications. The decrease in adsorption energies is confirmed by the first principle calculations which show that the relative energy values of methanol adsorption, conversion of methanol to CO and further to CO(2)on Pt/ZrC-XC are much more negative than Pt/XC and bare Pt, indicating the thermodynamic feasibility of the reaction. The electrochemical analysis shows that, Pt/a-ZrC800-XC electrocatalyst provides higher mass activity, higher antipoisioning activity, and required stability towards methanol electrooxidation reaction.