Enhancing the CO Preferential Oxidation (CO-PROX) of CuO–CeO₂/Reduced Graphene Oxide (rGO) by Conductive rGO-Wrapping Based on the Interfacial Charge Transfer

Abstract: Reduced graphene oxide supported CuO–CeO₂ nanospheres (CuO–CeO₂/rGO) were prepared by a facile hydrothermal method. The chemically bonded CuO–CeO₂/rGO composites effectively enhanced their activity in the CO preferential oxidation (CO-PROX), while moderate rGO content (7 mg) exhibited an improvement on the catalytic activity. The prepared composite with 14 wt% rGO showed the highest catalytic activity, exceeding that of pure CuO–CeO₂ and mechanically mixed CuO–CeO₂ and rGO, respectively. The enhancement in the CO-PROX activity was attributed to the synergetic effect between rGO and CuO–CeO₂ nanospheres. Besides supported rGO layers as excellent electron transporters, CuO–CeO₂ nanospheres in turn act as the skeleton to brace two-dimensional structure to prevent from further curling, crumpling and aggregation of rGO. In the presence of capping agents during synthesis, limited catalytic activities of CuO–CeO₂/rGO was observed due to the restrained interfacial charge transfer between CuO–CeO₂ and rGO layers. This work, focusing on effective CO-PROX through a chemically bonded interface between CuO–CeO₂ and rGO, can provide a new insight for design of new heterogeneous catalysts. Graphical Abstract: Chemical bonded CuO–CeO₂/rGO nanocomposites synthesized by a facile hydrothermal approach have shown high CO-PROX activity. Excellent charge transport between rGO layers and CuO–CeO₂ nanospheres via their interfaces leads to enhanced catalytic activity for CO-PROX.