Towards mass production of Au nanoparticles supported on montmorillonite microspheres for catalytic reduction of 4-nitrophenol

Noble metals supported on substrates have been proven as highly efficient catalysts for the reduction of nitrocompounds. However, their large-scale applications are still limited by the problems of fouling and transport during the mass production process. Herein, we first fabricated a spherical montmorillonite (Mt) substrate via spray drying technique, followed by the deposition of Au NPs through polydopamine chemistry to synthesize spherical Au nanoparticles supported Mt (Au@Mt) microspheres. The Au loading is 14.5 wt%, whereas the specific surface area of the Au@Mt microspheres is 47.3m2 g−1, endowing the prepared Au@Mt microspheres with excellent catalytic activity to the reduction of 4-nitrophenol (4-NP) in the presence of NaBH4 with the optimized apparent reduction rate constant higher than 1.05 min−1. Furthermore, the microspheres can be easily recycled with self-sedimentation without any devices involved and showed excellent stability and recyclability for at least 20 cycles without almost unchanged spherical morphology and catalytic performance. Our straightforward strategy to solve the issue of the mass production process through granulation of amorphous nanomaterial substrate facilitates the practical application of these catalysts in the reduction of nitro-compounds.