Nitrogen Doped Carbon Nanotubes and Nanofibers for Green Hydrogen Production: Similarities in the Nature of Nitrogen Species, Metal–Nitrogen Interaction, and Catalytic Properties

The effect of nitrogen doped bamboo-like carbon nanotubes (N-CNTs) on the properties of supported platinum (0.2 and 1 wt %) catalysts in formic acid decomposition for hydrogen production was studied. It was shown that both impregnation and homogeneous precipitation routes led to the formation of electron-deficient platinum stabilized by pyridinic nitrogen sites of the N-CNTs. The electron-deficient platinum species strongly enhanced the activity and selectivity of the Pt/N-CNTs catalysts when compared to the catalysts containing mainly metallic platinum nanoparticles. A comparison of bamboo-like N-CNTs and herring-bone nitrogen doped carbon nanofibers (N-CNFs) as the catalyst support allowed us to conclude that the catalytic properties of supported platinum are determined by its locally one-type interaction with pyridinic nitrogen sites of the N-CNTs or N-CNFs irrespective of substantial structural differences between nanotubes and nanofibers.