DeNovo Synthesis of Gold-Nanoparticle-Embedded, Nitrogen-Doped Nanoporous Carbon Nanoparticles (Au@NC) with Enhanced Reduction Ability

A denovo synthesis of gold-nanoparticle-embedded, nitrogen-doped nanoporous carbon nanoparticles (Au@NC) was investigated in this work. Chloroauroic acid was encapsulated inside zeolitic imidazolate framework-8 (ZIF-8) nanoparticles during the synthesis and later reduced into gold nanoparticles. The as-synthesized gold-nanoparticle-embedded ZIF-8 (Au@ZIF-8) was then carbonized into Au@NC to enhance the stability of the nanoporous support. The results show that Au@NC exhibits a porous structure containing 3wt% of gold. 2-Methylimidazole provided an abundant amount of nitrogen (19wt%) on the carbon matrix, which resulted in a hydrophilic and positively charged surface that is useful for the reduction of 4-nitrophenol. The results of the catalytic reaction indicate that synthesized Au@NC could act as an effective catalyst with a turnover frequency (TOF) of 1185g(-1)s(-1), which is higher than that of conventional naked Au nanoparticles (TOF: 339g(-1)s(-1)) and that of Au nanoparticles on activated carbon (TOF: 89g(-1)s(-1)). We propose that the enhanced performance of Au@NC resulted from homogeneous distribution of Au nanoparticles along with the hydrophilic and positively charged nitrogen-doped carbon surface.