Importance of Low Dimensional CeOx Nanostructures in Pt/CeOx–TiO2 Catalysts for the Water–Gas Shift Reaction

CO2 and H2 production from the water–gas shift (WGS) reaction was studied over Pt/CeOx–TiO2 catalysts with incremental loadings of CeOx, which adopts variations in the local morphology. The lowest loading of CeOx (1 wt % to 0.5 at. %) that is configured in its smallest dimensions exhibited the best WGS activity over larger dimensional structures. We attribute this to several factors including the ultrafine dispersed one-dimensional nanocluster geometry, a large concentration of Ce3+ and enhanced reducibility of the low loadings. We utilized several in situ experiments to monitor the active state of the catalyst during the WGS reaction. X-ray diffraction (XRD) results showed lattice expansion that indicated reduced ceria was prevalent during the WGS reaction. On the surface, Ce3+ related hydroxyl groups were identified by diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS). The enhanced reducibility of the catalyst with the introduction of ceria was further revealed by H2-temperature progr...