Gold nanomaterials are increasingly anticipated to be used in a wide variety of applications, including conductive materials, solar cells, pharmaceutical products, sensor probes to detect pathogens, and catalysts. Gold nanomaterials are generally produced by adding a reducing agent to a solution containing gold ions and then reducing the gold ions. Due to the challenge of controlling the shape and crystal growth direction of gold nanomaterials, a complex process has conventionally been used, resulting in high costs and environmental loads. The task was to develop a less complex, environmentally compatible and energy-efficient process for producing gold nanomaterials that can be used to control the shape and the crystal growth direction of the nanoparticles.

The researchers have developed a simple process for synthesizing single-crystalline gold nanomaterials using bilayer membranes as a template which are formed by self-assembly of a succinic acid derivative in water. Gold nanomaterials are widely used in conductive materials, solar cells, sensor probes, and catalysts, and are usually obtained by reducing gold ions. The researchers have discovered that the succinic acid derivative can rapidly reduce gold ions and the bilayer membranes of this compound act as a template for controlling the direction of crystal growth. An aggregate of sheet-like gold nanomaterials (gold nanosheets), several tens of nanometers thick and about 6 micrometers wide, was synthesized using the developed process. The aggregate of gold nanosheets is soft, plastic, and deformable into different shapes and exhibits electrical conductivity in the as-prepared state. Its conductivity can be significantly improved by mechanical compression. This achievement has opened the path to a fast production process in which the shape and crystal growth direction of gold nanomaterials can be controlled.