Carbon nanomaterials as potential substitutes for scarce metals

There is growing evidence of resource problems related to the use of scarce metals in society, including the long-term risk of world-wide depletion of high-grade ores, shorter-term supply deficits and mineral related conflicts. In this study, we explore the idea that scarce metals may be substituted by nanomaterials based on the abundant element carbon, primarily graphene, nanotubes and fullerenes. We depart from a list of 14 geochemically scarce metals: antimony, beryllium, chromium, cobalt, gallium, germanium, gold, indium, niobium, platinum, silver, tantalum, tin and tungsten. We then review scientific papers and patents for carbon nanomaterial technologies that, if successfully implemented, could reduce or eliminate the need for each metal in its main application. For all main applications except for gold in jewelry, such technologies were identified. Most of the identified technologies were described in more than 100 papers. This suggests that there is an ongoing promising development of carbon nanomaterial technologies for applications currently relying on scarce metals. However, we recommend further studies to scrutinize these technologies regarding their environmental performance to avoid problem shifting from metal scarcity to (eco)toxic effects of the carbon nanomaterials themselves or other impacts related to their production and use.