Ionic liquid-assisted synthesis of 3D nanoporous gold and its superior catalytic properties

Abstract

In this work, a simple, rapid and economic one-pot strategy is developed for the synthesis of 3D nanoporous gold (NPG) in aqueous solution with the assistance of a functionalized ionic liquid, 1-hydroxyethyl-3-methylimidazolium chloride ([HEmim]Cl), at room temperature. It is shown that 3D NPG is constructed from twisted and interconnected Au nanochains with diameters of approximately 40 nm. This material has a high specific surface area of 22.77 m² g⁻¹ and various porous structures, including macropores, mesopores and micropores. Yet, there are lots of crystal defects, such as a twin boundary, edge atoms and amorphous regions. It is demonstrated that [HEmim]Cl plays an important role in directing the growth and assembly of 3D NPG, and the ionic liquid concentration, the amount of reductant and the reaction temperature also have influences on the morphology and structure of NPG to a certain extent. Based on control experiments, a possible growth mechanism is illustrated for the formation of 3D NPG. In addition, the as-prepared 3D NPG exhibits superior catalytic activities for both the reduction of p-nitrophenol and the degradation of methylene blue in water, which can be completed in 14 min and 8 min, respectively, at 25 °C.