Porous Montmorillonite@Graphene Oxide@Au Nanoparticle Composite Microspheres for Organic Dye Degradation

Gold nanoparticles (Au NPs) supported on graphene oxide (GO) have been proven as a high-performance catalyst for fast reduction of organic contaminants due to their strong electrostatic interactions to enhance the electron transfer ability from an electron donor to an electron acceptor. However, GO sheets in the solution often suffer from the reaggregated problems due to the strong π–π electron interaction, greatly affecting the catalytic efficiency. Herein, we solved this drawback through supporting tiny GO@Au NPs nanocomposites on the micrometer-sized porous spherical montmorillonite (SMt) substrate. SMt with a large specific surface area was first fabricated through the spray-drying technique, followed by wrapping with GO sheets and then in situ growth of Au NPs to synthesize SMt@GO@Au NPs microspheres through the polydopamine chemistry approach. The prepared SMt@GO@Au NPs microspheres presented an excellent catalytic reduction ability toward organic dyes or intermediate including methylene blue (MB), 4-nitrophenol (4-NP), rhodamine 6G (R6G), acid fuchsin (AF), and Congo red (CR). Moreover, the microsized self-sedimentary SMt@GO@Au NPs microspheres could be facilely recovered from the catalytic system and possessed sustainable recyclability.