Aqueous synthesis of highly monodisperse sub-100 nm AgCl nanospheres/cubes and their plasmonic nanomesh replicas as visible-light photocatalysts and single SERS probes

Despite the distinctive electrochemical and photocatalytic properties of nanostructured silver chloride (AgCl), the shape- and size-dependence of their properties have not been thoroughly investigated to date. The most substantial reason responsible for this incomplete study and the subsequent limited applications is the failure in controlling the structure of AgCl nanomaterials, mainly owing to the challenging synthetic conditions including organic phase and high reaction temperature. In this work, we reported a rapid one-pot room-temperature aqueous synthesis of highly monodisperse sub-100 nm AgCl nanomaterials with various shapes and sizes by controlling the precursor (Ag⁺ and AuCl₄ ^-) ratios. The remaining unreacted metal precursors (Ag⁺ and AuCl₄ ^-) used to produce AgClNC were subsequently reduced by ascorbic acid on the surface of the synthesized AgCl nanomaterials to form Ag/Au bimetallic nanomesh structures (AgClNC#AuAgCMs and SMs). After the removal of the AgCl nanotemplates, only nanomesh structures (AuAgCMs and SMs) were obtained. Importantly, we successfully decreased the size of the AgCl nanomaterials which were replicated into bimetallic spherical and cubic nanomesh structures that were small enough (∼100 nm) to show intense surface-plasmon-absorption bands. Based on these unique chemical and physical properties, we could take advantage of the plasmonic photocatalysis properties of the complex comprising semiconducting AgCl/metallic nanomesh replica for the complete removal of the environmentally harmful Cr⁶⁺ in the presence of sacrificial agents such as formic acid. Finally, the novel bimetallic nanomesh structures proved themselves to exhibit intense surface-enhanced Raman scattering properties in a single-particle enhancing the electromagnetic field.