Copper-Based Nanocatalysts with SiO2 and Carbon Dual-Layer Coatings and Metallic Ni/CuNi Decoration toward Highly Efficient Nitroaromatics Reduction.

Nanocomposites with novel architectures and multifunctional properties have attracted extensive attention among related researchers. Herein, we develop a magnetically responsive Ni/CuNi nanoparticle (NP) decoration of Cu-based composites that could serve as recoverable nanocatalysts for nitroaromatics reduction. The nanocatalysts consist of an inner copper core and abundant tiny satellite Ni/CuNi NPs, which are tightly combined as a stable whole part by a silica interlayer and a carbon outer layer. In addition to the high catalytic activity, the outer Ni/CuNi NPs exhibit a strong magnetic response toward the external magnetic field, thereby offering a convenient way to separate the composites from the reaction solution. Moreover, characterization results reveal that high annealing temperature (above 700 °C) favors the construction of yolk-shell nanostructures and the formation of outer bimetallic CuNi NPs. As a result, owing to the excellent catalytic performance of the Cu inner cores, the high coverage of outer Ni or CuNi NPs, and the unique sandwich-like structure, the resultant Cu@SiO2@C-Ni composites show the use of such magnetically responsive recoverable nanocatalysts for the 4-nitrophenol reduction. Hence, this research could provide new guidelines for designing and synthesizing novel and efficient copper-based composites for other fields, such as carbon dioxide reduction, energy storage, and batteries.