Electrochemical promotion of the water-gas shift reaction on Pt/YSZ

S. SOUENTIE; L. LIZARRAGA; J.L. VALVERDE; P. VERNOUX

Montreal

Encuentro; 219th Electrochemical Society Meeting; 2011

Electrochemical Society

The effect of the electrochemical promotion of catalysis was investigated on the water-gas shift reaction over porous Pt catalyst electrodes interfaced with YSZ. The study was conducted in a fuel cell type electrochemical reactor operated at temperatures from 300°C to 400°C, under ratio values from 2.85 to 31. Positive potential application (+2.5 V), i.e. O2- species supply to the catalyst surface, caused a small decrease in the reaction rate, while negative potential application (-1.5 V) resulted in a pronounced rate increase, up to 200%, with apparent Faradaic efficiency values up to 110. The obtained increase of the rate upon negative polarization was attributed to the partial reduction of the YSZ surface and the stabilization of the adsorbed OH species at the vicinity of the Pt particles, but mainly to the weakening of the Pt-CO bond strength, upon Oδ- ion pumping from the catalyst surface, which results in Pt work function decrease.