Hydrothermal synthesis of sandwich interspersed LaCO3OH/Co3O4/graphene oxide composite and the enhanced catalytic performance for methane combustion

Abstract

Novel structured LaCO3OH/Co3O4/graphene oxide composite was synthesized through a hydrothermal process using a certain ratio of urea (N), LaCoO3 (LC) and graphene oxide (GO) as starting materials. Morphology characterizations showed that as-prepared composite had sandwich structure interspersed on graphene oxide sheets. The LaCO3OH nano-sheets were self-organized into stratiform nano-structures, where spherical Co3O4 nano-particles with a diameter of 17–31 nm were homogeneously distributed between two adjacent LaCO3OH nano-sheets, forming sandwich structure. At the same time, the sandwich structure inlaid on the surface of two-dimensional GO, forming sandwich structure interspersed morphology. The results indicated that the amount of urea additive (m(N)) played a key role in the formation of the neoteric morphology. The LaCO3OH/Co3O4/graphene oxide composite showed optimized catalytic performance for methane combustion as 50% methane conversion at 315 °C and 90% at 420 °C when m(N)/m(LC) = 5, which can match the activity of noble metal catalysts. The enhanced catalytic performance was attributed to its unique loaded structure with high surface area and more exposed active sites, which showed enhanced application in methane combustion as a new type of Pt-group metals free catalyst. In addition, stability performance was systematically studied, indicating that the synthesized catalyst has great potential for industrial applications.