Effect of N-doping and carbon nanostructures on NiCu particles for hydrogen production from formic acid

A series of NiCu based catalysts were prepared using different carbon nanostructure as support and loading 2.5 wt% of each metal. The studied nanocarbon materials were: reduced graphene oxide (rGO), N-doped reduced graphene oxide (NrGO), high surface area graphite (HSAG), single and multiwalled carbon nanotubes (SWCNT and MWCNT), N-doped carbon nanotubes (NCNT), spheres of xerogel carbons (SXC) and N-doped SXC (NSXC). The effect of N-doping, electronic properties and morphology of the carbon nanostructures on the metallic particle size was studied as well as their capacity to produce high purity hydrogen from formic acid decomposition at low temperature. The NiCu based catalysts tested are highly selective to H2 (98−94 % at conversions above 95 %). The site time yield (STY) of the catalysts follows the order: NCNT > SXC > SWCNT∼HSAG∼rGO10>rGO325>MWCNT∼NSXC > NrGO325>NrGO10, indicating that N-doped catalysts are less active, except in the case of NCNT which is ascribed to the N-pyrrolic heteroatoms of this material.