Tungsten carbide as supports for Pt electrocatalysts with improved CO tolerance in methanol oxidation

摘要

One anti-CO-poisoning Pt-WC/C catalyst for methanol electro-oxidation is prepared in this work, through depositing platinum on tungsten carbide support using an intermittent microwave heating (IMH) method. The catalyst presents an improved methanol oxidation performance evidenced by a negative shift in onset potential, and increase of peak current density, compared with a commercial Pt/C one. CO stripping experiments indicate that the adsorbed CO is able to be oxidized and removed from the Pt-WC/C catalyst more easily, attesting the enhanced capability of anti-poisoning to CO-like species. Theoretical calculation further provides evidence that the surface electronic structure in Pt-WC/C and Pt/C catalysts is likely different. WC supports could lead to much stronger negative electronic property, which is beneficial for avoiding CO adsorption on the Pt-WC/C catalyst. In the mean time, the electron donating effect generated by WC supports also promotes the ability to oxidize the adsorbed CO-like species on catalysts. In good agreement with experimental results, the theoretical calculation proves the anti-CO-poisoning nature of the Pt-WC/C catalyst, and well explains the origin of the improvement in the electrochemical catalytic performance for effectively accelerating the oxidation of CO to CO_2 in methanol oxidation.