Palladium-Modified Tungsten Carbide for Ethanol Electrooxidation: From Surface Science Studies to Electrochemical Evaluation

Abstract

The current study explores the potential utilization of tungsten monocarbide (WC) and Pd-modified WC as anode electrocatalysts in direct methanol fuel cells (DMFC). Density functional theory (DFT) calculations and ultrahigh vacuum (UHV) studies were performed to determine how the presence of Pd affected the bonding and reaction pathways of methanol on the WC surface. These studies showed that the WC surface was very active toward the O–H bond cleavage to produce a methoxy intermediate, although WC was less active for the C–H bond scission. Adding Pd on WC enhanced the scission of the C–H bonds of methoxy, suggesting a synergistic effect of using Pd-modified WC as electrocatalysts for methanol decomposition. The prediction from UHV studies was verified in electrochemical experiments using cyclic voltammetry (CV) and chronoamperometry (CA) measurements of electro-oxidation of methanol in an alkaline environment.