Metal-free carbocatalyst for catalytic hydrogenation of N-containing unsaturated compounds

Abstract

Eco-friendly carbocatalyst is extremely desirable in organic catalysis and wastewater treatment. Herein, we reported a one-pot synchronous hydrothermal process to synthesize a highly efficient N doped holey graphene (NHG) carbocatalyst, in which graphene oxide nanosheets are self-assembled, reduced, chemically etched, and simultaneously doped with nitrogen to form a graphene hydrogel in the presence of H2O2 and NH4OH. Benefiting from the good hydrophilicity, unique hierarchical porous structure, large specific surface area (322.1 m2 g−1), and high N content (9.77 at. %), the resultant NHG carbocatalyst exhibits an excellent catalytic performance for the hydrogenation of N-containing unsaturated compounds. In 4-nitrophenol reduction reaction, the NHG carbocatalyst delivers a turnover frequency of 3.32 × 10−2 min−1. This catalytic activity is superior to that of the commercial Pd/C (5.0 wt%), other previously reported carbocatalysts, and many noble-metal-based catalysts. Furthermore, the molecular structure analysis combined with density functional theory calculations elucidate metal-free catalytic mechanism of hydrogenation reaction for unsaturated chromophore groups in N-containing organic dyes.