Ruthenium Clusters on Carbon Nanofibers for Formic Acid Decomposition: Effect of Doping the Support with Nitrogen.

The catalytic properties of 1 wt % Ru catalysts with the same mean Ru cluster size of 1.4-1.5 nm supported on herringbone-type carbon nanofibers with different N contents were compared for H₂ production from formic acid decomposition. The Ru catalyst on the support with 6.8 wt % N gave a 1.5-2 times higher activity for the dehydrogenation reaction (CO₂, H₂) than the catalyst on the undoped support. The activity in the dehydration reaction (CO, H₂O) was the same. As a result, the selectivity to H₂ increased significantly from 83 to 92 % with N-doping, and the activation energies for both reactions were close (55-58 kJ mol⁻¹). The improvement could be explained by the presence of Ru clusters stabilized by pyridinic N located on the open edges of the external surface of the carbon nanofibers. This N may activate formic acid by the formation of an adduct (>NH⁺HCOO⁻) followed by its dehydrogenation on the adjacent Ru clusters. [ABSTRACT FROM AUTHOR]