Selective reduction of nitrobenzene to aniline over electrocatalysts based on nitrogen-doped carbons containing non-noble metals

Non-noble metals (Fe, Co or Cu) supported on N-doped carbons were investigated for the first time as electrocatalysts for the reduction of nitrobenzene to aniline in a half-cell setup. The electrocatalysts were prepared by pyrolysis of composites of activated carbon (AC) and polyaniline (PANI) with incorporated metal sites. The electrocatalyst performance was strongly influenced by the nature of the metal and by the synthesis method. For the latter, a different optimum was identified for each metal. The Cu-based electrocatalyst synthesised with a low amount of PANI and Cu relative to AC, was identified as the best electrocatalyst based on its onset potential, kinetic current density and selectivity to aniline. Most importantly, unprecedented selectivity to aniline was obtained (82%, as determined by chronoamperometry) with this electrocatalyst in a half-cell setup. This makes it a promising candidate for the electrochemical cogeneration of the industrially valuable aniline and electricity in a proton-exchange membrane fuel cell.