Immobilization of a layer of carbon nanofibres (CNFs) on Ni foam: A new structured catalyst support

Abstract

This work describes the preparation of new materials based on immobilizing carbon nanofibres (CNFs) on the surface of Ni foam. CNFs were catalytically synthesized by decomposition of ethene over the Ni foam. The influence of formation conditions on the morphology of the CNFs, on the mechanical stability of the CNFs–Ni-foam composite structures and on the attachment of the CNFs to the Ni foam is discussed. The surface area of the Ni–CNFs-foam composite increased with the loading of CNFs, from less than 1 m² g⁻¹ to 30 m² g⁻¹ for 50 wt.% CNFs on the foam. The layer of the CNFs was highly open with a pore volume of 1 cm³ g⁻¹ CNFs. Stable Ni–CNFs-foam composite structures can be obtained under the conditions that the extent of corrosive metal dusting of Ni is limited, via decreasing the temperature and/or the formation time. Some metal dusting is, however, needed to form small Ni particles that allow formation of CNFs. The extent of corrosive metal dusting determines to what extent CNFs are weakly attached. The remaining CNFs, at least 80%, are remarkably strongly attached. Every single CNF is bonded to the Ni structure, probably via penetration of the CNFs into the polycrystalline Ni foam. Controlling the conditions of CNFs formation is vital in order to optimise the mechanical stability of the CNF–Ni-foam composite structures as well as the strong attachment of the CNFs to the surface of the Ni foam.