Construction of Cu-Ce/graphene catalysts via a one-step hydrothermal method and their excellent CO catalytic oxidation performance.

Abstract

Cu–Ce/graphene catalysts show high dispersion of metal particles and excellent activity and stability for catalytic oxidation. In this study, a hydrothermal method was used to synthesize a series of bimetallic Cu–Ce/graphene catalysts, and the effects of the proportions of Cu and Ce on CO oxidation were investigated in detail. Indispensable characterizations such as XPS, XRD, TEM, BET, and H2-TPR were conducted to explore the effect of the Cu/Ce molar ratio and the metal valence on the activity and determine the structure–performance relationship. The results showed that bimetallic supported catalysts, such as 3Cu5Ce/graphene, 1Cu1Ce/graphene, and 5Cu3Ce/graphene, possessed significant catalytic activity. Especially, the 5Cu3Ce/graphene catalyst showed highest catalytic activity for CO oxidation, the T100 value was 132 °C, and the apparent activation energy was 68.03 kJ mol−1. Furthermore, the stability of the 5Cu3Ce/graphene catalyst was outstanding, which could be maintained for at least 12 h. Moreover, the CeO2 particles were well crystalline with the size 5–9 nm in these catalysts, and the CuO nanoparticles were well dispersed on CeO2 and graphene. Notably, the ratio of Cu/Ce in the catalyst was higher, the interaction between the Ce species and the graphene was stronger, and the Cu species were more easily reduced; this was beneficial for the oxidation of CO.