Synthesis of gold nanoparticle-loaded magnetic carbon microsphere based on reductive and binding properties of polydopamine for recyclable catalytic applications

Abstract

An efficient and green method was proposed to synthesise Au nanoparticle (Au NP)-decorated Fe₃O₄@porous carbon core–shell nanoparticles (denoted as Fe₃O₄@C–Au). In this synthetic strategy, polydopamine (PDA) was prepared by spontaneous polymerization of dopamine, which works as both a carbon precursor and a reducing agent. The thickness of the carbon layer is about 50 nm and could be easily adjusted by changing the polymerization time. The as-prepared Fe₃O₄@C–Au, which was well characterized by transmission electron microscopy (TEM), scanning electron microscopy (SEM), X-ray diffraction (XRD), vibrating sample magnetometry (VSM), X-ray photoelectron spectroscopy (XPS), Raman spectroscopy (RS) and Fourier transform infrared (FTIR), showed excellent catalytic performance in the reduction of 4-nitrophenol (4-NP) to 4-aminophenol (4-AP) in aqueous solution using sodium borohydride as a hydrogen source. Owing to its superparamagnetic property of the Fe₃O₄ core and the stability of the carbon shell, the catalyst could be easily separated using an external magnet and shows excellent reusability (almost the same activity as the fresh catalyst after eight catalytic cycles). The facile and green preparation, high catalytic capability and recyclability give Fe₃O₄@C–Au a great development potential in the industrial wastewater treatment.