Three-dimensionally ordered macroporous carbon-encapsulated Ni nanoparticles for the preparation of magnetically recoverable catalyst

A colloidal templating method was applied to fabricate a composite of three-dimensionally ordered macroporous carbon-encapsulated Ni nanoparticles (3DOM Ni@C) by using citric acid and nickel nitrate as raw materials and polymethyl methacrylate (PMMA) microspheres as template. The products were characterized by XRD, TEM, ICP, TG-DTA, XPS, N2 adsorption-desorption and magnetic measurement. In 3DOM Ni@C, metallic Ni nanoparticles (4.0–7.0 nm) were tightly wrapped by multilayer graphitized carbon with a highly ordered three-dimensionally arrangement in a large scale. While sufficient citric acid was supplied, multilayer carbon nanotubes were formed with the Ni nanoparticles at one end of them. Cu-supported 3DOM Ni@C materials were found to be highly efficient for catalyzing the reduction of 4-nitrophenol (4-NP). The rate constant reached 0.0512 s−1 over 3.5%Cu/3DOM Ni@C-1. Importantly, the catalyst showed good recycling performance due to its magnetically recoverable property and the improved stability brought by the encapsulated structure. [Display omitted] •A simple method for the preparation of Ni@C composite was developed.•Ni nanoparticles were tightly wrapped by multilayer graphitized carbon with a 3DOM framework.•3DOM Ni@C was magnetically recoverable with improved stability for liquid-phase reaction.•High activity and good recycling performance for 4-NP reduction was obtained.