Copper-decorated iron oxide nanoparticles highly dispersed on coal-based activated carbons: a recoverable catalyst for the reduction of 4-nitrophenol, Congo red, and Rhodamine B

Developing an efficient and long-lasting catalyst is of great importance for the reductive degradation of pollutants. Herein, we report a simple co-precipitation method to prepare copper-decorated iron oxide/activated carbon (AC) magnetic catalysts, in which copper-decorated iron oxide nanoparticles are uniformly distributed on coal-derived activated carbons (ACs). Both 4-nitrophenol and structurally complex dyes (Rhodamine B and Congo red) can be degraded by the copper-decorated iron oxide/AC nanocomposites in the presence of sodium borohydride. In particular, 4-nitrophenol can be reduced to 4-aminophenol within 6 minutes at room temperature, and the conversion efficiency remains above 96% after five cycles, while an external magnetic field easily recovers the catalyst during cycling. The excellent catalytic activity of copper-decorated iron oxide/AC can be attributed to the synergistic coupling between copper-decorated iron oxide nanoparticles and coal-based activated carbons, the high surface area of the AC and the small size of the copper-decorated iron oxide nanoparticles. The advantages of low cost, easy recovery, universal catalytic reduction, high activity, and durability make the proposed catalysts promising for a wide range of practical applications.