Au nanoparticle/graphene oxide hybrids as stabilizers for Pickering emulsions and Au nanoparticle/graphene oxide@polystyrene microspheres

Gold nanoparticle/graphene oxide hybrids (AuNP/GO) were easily fabricated by a redox reaction between GO and chloroauric acid without using any additional reductant and then used to stabilize Pickering emulsions. Factors affecting the properties of the emulsions were studied, including the HAuCl4/GO mass ratio used to prepare the AuNP/GO, the oil/water ratio, the AuNP/GO concentration, the pH value, and the type and concentration of electrolytes. The emulsions were more stable when stabilized by AuNP/GO made from HAuCl4/GO mass ratios of 0.375–0.5. High pH values and AuNP/GO concentrations that were too high or too low were unfavorable to the stability of the Pickering emulsions. Adding electrolytes to the systems improved the stability of the Pickering emulsions owing to the reduction of repulsive interactions between AuNP/GO sheets. The AuNP/GO stabilized Pickering emulsions were used to prepare AuNP/GO supported polystyrene (PS) microspheres (AuNP/GO@PS) by polymerizing the Pickering emulsion. The catalytic performance of AuNP/GO@PS for the reduction of 4-nitrophenol was then studied.