Microwave-Assisted Controllable Synthesis of Nickel Nanoparticles Embedded in Mesoporous Silica for Catalytic Reduction of 4-Nitrophenol

Nickel nanoparticles embedded in mesoporous silica (Ni/SiO 2 ) ${}_2)$ were successfully synthesized by microwave-assisted in situ self-assembly method using colloidal silica, urea and nickel nitrate as precursors and glucose as carbon template, which resulted in mesoporous structure of silica through removal of template. Ni nanoparticles were uniformly well-dispersed within mesoporous silica, which were 3.5–4.0 $$ nm in diameter and had a very narrow particle size distribution. In addition, particle size of Ni nanoparticles can be controllably adjusted by microwave power. As-prepared Ni/SiO 2 catalyst exhibited better catalytic activity for reduction of 4-nitrophenol (4-NP) to 4-aminophenol (4-AP) than Ni/SiO 2 -IM catalyst, which was mainly attributed to confinement effect of mesoporous silica support. This simple and versatile method can also be extended to cover many kinds of other supported catalysts for broad applications in many other catalytic reactions in the future.