Theoretical and Experimental Studies of Ethanol Decomposition and Electrooxidation over Pt-Modified Tungsten Carbide

Density functional theory (DFT) calculations, surface science experiments, and electrochemical measurements were performed to investigate tungsten monocarbide (WC) and Pt-modified WC for ethanol electrooxidation. DFT was used to calculate the binding energies of ethanol and potential reaction intermediates on model surfaces. Temperature programmed desorption (TPD) experiments were performed under ultrahigh vacuum (UHV) conditions to determine the decomposition pathways of ethanol on WC and Pt-modified WC surfaces. On WC the major pathway was C-O scission to produce ethylene, while on Pt/WC the preferred pathway was the C-C bond cleavage. High-resolution electron energy-loss spectroscopy (HREELS) was used to further understand the bond-breaking sequence of ethanol on WC and Pt/WC surfaces. Furthermore, electrochemical half-cell measurements were performed for Pt/WC in acidic electrolytes containing ethanol. Pt/WC was shown to be active for the electrooxidation of ethanol using both cyclic voltammetry (CV) and chronoamperometry (CA). In-situ infrared spectroscopy was also employed to demonstrate that Pt/WC was more effective than Pt for the total oxidation of ethanol to CO2.