N, P Dual-Doped Carbons as Metal-Free Catalysts for Hydrogenation.

The activation of molecule hydrogen (H) by metal-free catalysts is always a challenge in the field of catalysis. Herein, a series of N, P dual-doped carbon catalysts were constructed by the pyrolysis of chitosan and phytic acid and utilized as metal-free catalysts for the hydrogenation of nitrobenzene. The characterization indicated that the doping of phosphorus atoms not only formed the species with catalytic activity for hydrogenation reaction but also promoted the doping of N. The experimental results indicated that their catalytic performance could be improved by the regulation of pyrolysis temperature and heating rate. CP-900-1 (pyrolysis at 900 °C with a heating rate of 1 °C/min) exhibited a promising catalytic activity with >99% nitrobenzene conversion. N, P codoping was the key factor to its catalytic performance. All results indicated that the excellent catalytic activity of CP-900-1 was attributed to the synergistic interaction among pyridinic N, P-C species, and graphitic N. This work provides an effective route for the rational design and construction of highly efficient metal-free catalysts for hydrogenation.