Immobilization of N-doped carbon porous networks containing copper nanoparticles on carbon felt fibers for catalytic applications

Applying green techniques and treating organic pollutants efficiently in water can be regarded as one of the biggest challenges in chemistry. In this work, reduction of such environmental pollutants as toxic 4-nitrophenol, methylene blue and rhodamine B by NaBH4 was studied at room temperature using a series of surface modified carbon fiber felts with Cu(x wt%, x = 1.5, 3.0, 5.0) nanoparticles buried in a nitrogen-doped carbon porous network. The catalyst, referred to as Cu(x wt%)N-CF, was prepared by the pyrolysis of carbon fiber felts containing different amounts of the Cu(salen) complex at 650 degrees C for 2 h under argon atmosphere. The most efficient catalyst showing a high performance and recyclability could also be applied industrially for wastewater treatment due to its bulk structure. The catalytic efficiency of the synthesized composites was attributed to the high distribution of copper nanoparticles in the matrix of the modified carbon fibers felt. In the optimum conditions, Cu(1.5 wt%)/N-CF exhibited the highest rate constant, k = 0.045 s(-1) and TOF = 23.7(-1), at room temperature for reducing 4-nitrophenol to 4-aminophenol; this was significant in comparison with the expensive metal-based nanocatalysts. This reduction reaction, due to the large potential difference between BH4- as the donor and 4-nitrophenol as the acceptor, faces a large kinetic barrier and did not occur without the catalyst. Therefore, this composite could be an ideal platform for use as a sustainable and green heterogeneous catalyst in many chemical processes and wastewater treatments.