In-situ generation of gold nanoparticles on MnO₂ nanosheets for the enhanced oxidative degradation of basic dye (Methylene Blue)

In this work, the gold nanoparticles (Au-NPs) were in-situ generated on the surface of MnO₂ nanosheets to form MnO₂/Au-NPs nanocomposite in a simple and cost-effective way. Multiple experiments were carried out to optimize the oxidation of basic dye (Methylene Blue (MB)), including the molar ratio of MnO₂ to chloroauric acid (HAuCl₄), the pH of the solution and the effect of initial material. Under the optimal condition, the highest degradation efficiency for MB achieved to 98.9% within 60 min, which was obviously better than commercial MnO₂ powders (4.3%) and MnO₂ nanosheets (74.2%). The enhanced oxidative degradation might attribute to the in-situ generation of ultra-small and highly-dispersed Au-NPs which enlarged the synergistic effect and/or interfacial effect between MnO₂ nanosheets and Au-NPs and facilitated the uptake of electrons by MnO₂ from MB during the oxidation, thus validating the application of MnO₂/Au-NPs nanocomposite for direct removal of organic dyes from wastewater in a simple and convenient fashion.