Facile synthesis of nanostructured carbon materials over RANEY® nickel catalyst films printed on Al2O3 and SiO2 substrates†
A quick and convenient approach that combines a printing process and chemical vapor deposition is developed for facile construction of nanostructured metal–carbon composite structures. Films of porous RANEY® nickel catalyst particles are deposited on various substrates by stencil printing from dispersions of the catalyst and poly(methyl methacrylate) in 2-(2-butoxyethoxy)ethyl acetate. After removing the organic binders at elevated temperatures, the mesoporous Ni film is applied as a growth template for synthesizing nanostructured carbon materials on the surface. Depending on the synthesis conditions, carbon nanofibers and nanotubes, as well as graphite deposits, are found to form on the substrates, allowing a robust and scalable production of carbon based inert electrodes of high specific surface area. In addition to structural characterization of the composites by means of scanning and transmission electron microscopy, Raman spectroscopy, X-ray diffraction, thermal gravimetric and surface adsorption analyses, the produced carbon/RANEY® nickel composites are also studied as electrodes in electrochemical capacitors (specific capacitance of ∼12 F g−1) and in field emitter devices with a low turn-on field (<1.0 V μm−1). The results indicate the carbon/RANEY® nickel composites are suitable for direct integration on substrates used frequently in microelectronics.