Water, vortex device used to create gold nanoparticles

Golden particles. (Reference image from Pxhere.)

Flinders University researchers have produced a range of different types of gold nanoparticles by adjusting water flow in a novel vortex fluidic device (VFD)—without the need for toxic chemicals.

The green chemistry lab work on nano gold formation also led to the discovery of a contact electrification reaction in water in the device—which resulted in the generation of hydrogen and hydrogen peroxide.

In a paper published in the journal Small Science, the group explains that various sizes and forms of gold nanoparticles were developed from different VFD processing parameters and gold chloride solution concentrations.

“Through this research, we have discovered a new phenomenon in the vortex fluidic device. The photo-contact electrification process at the solid-liquid interface which could be used in other chemical and biological reactions,” Badriah Mazen Alotaibi, the study’s lead author, said in a media statement. “We also have achieved the synthesis of pure, pristine gold nanoparticles in water in the VFD, without the use of chemicals commonly used—and thus minimizing waste.”

According to Alotaibi, this method is significant for the formation of nanomaterials in general because it is a green process, quick, scalable and yields nanoparticles with new properties.

He explained that gold nanoparticles‘ size and shape are critical for a range of applications—from drug delivery to catalysis, sensing and electronics—due to their physical, chemical and optical properties.

The vortex fluidic device, created a decade ago by the paper’s senior author and Flinders University professor Colin Raston, is a rapidly rotating tube open at one end with liquids delivered through jet feeds. Different rotational speeds and external applications of light in the device can be used to synthesize particles to specification.

“Researchers around the world are now finding the continuous flow, thin film fluidic device useful in exploring and optimizing more sustainable nano-scale processing techniques,” Raston said. “In this latest experiment, we hypothesize that the high shear regimes of the VFD led to the quantum mechanical effect known as contact electrification, which is another exciting development.”

In the researcher’s view, this discovery is a paradigm shift in how to make materials in a controlled way using water, with no other chemicals required.

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