Optimum Preferential Oxidation Performance of CeO2-CuO x-RGO Composites through Interfacial Regulation.

Interfacial regulation offers a promising route to rationally and effectively design advanced materials for CO preferential oxidation. Herein, we initiated an interfacial regulation of CeO2-CuO x-RGO composites by adjusting the addition sequence of the components during the support formation. The presence of RGO along with the sequence tuning of the components is confirmed to survey the changes of the oxidation state of copper species, the content and distribution of the Cu+ site, and the synergistic interactions between Cu-Ce mixed oxides and reduced graphene oxide (RGO) over the catalysts. These catalysts were systematically characterized by inductively coupled plasma, X-ray diffraction, transmission electron microscopy/high-resolution transmission electron microscopy, hydrogen temperature-programmed reduction, X-ray photoelectron spectra, thermal gravimetric analysis, Raman spectra, and in situ diffuse reflectance infrared Fourier transform spectroscopy measurements. The results show that RGO is favorable for the generation of Cu+ and the dispersion of copper-cerium species in the as-prepared catalysts. Furthermore, by multi-interfacial regulation of the CeO2-CuO x-RGO composites, the catalyst CeO2/CuO x-RGO exhibits a strikingly high catalytic oxidation activity at a low temperature coupled with a broader operation temperature window (i.e., CO conversion >99.0%, 140-220 °C) in the CO-selective oxidation reaction, which has been attributed to the high content of the active species Cu+ enriched on the surface, the highly dispersed copper oxide clusters subjected to a strong interaction with ceria, and the synergistic interactions between Cu-Ce mixed oxides and RGO.