Producing plasmonic particles the environmentally friendly way

Silver nanoparticles are widely used in a range of fields, from catalysis to biomedicine and plasmonics, and a range of techniques have been developed to synthesize these nanostructures. The plasma nanoscience techniques now being put forward by our group at…

Silver nanoparticles are widely used in a range of fields, from catalysis to biomedicine and plasmonics, and a range of techniques have been developed to synthesize these nanostructures. The plasma nanoscience techniques now being put forward by our group at Shanghai Jiao Tong University, People’s Republic of China, and CSIRO Materials Science and Engineering, Australia, are alternative ways to synthesize these nanoparticles in an environmentally friendly way using atmospheric microplasma-assisted electrochemistry. An added plus is that the size of the particles and the spacing between them can be better controlled – a non-negligible advantage when it comes to making improved working devices from these materials.

A stabilizer-free method for producing Ag nanoparticles

Plasma-assisted electrochemistry involves bringing a microplasma into contact with an electrolyte containing metal salts (in this case, silver nitrate – see figure). The plasma is a source of electrons that reduce the silver ions in solution, and then collect into silver nanoparticles. This technique is a safer alternative to synthesis methods that involve toxic chemical-reducing agents such as sodium borohydride. It does not produce undesired by-products, and the shape and size of the nanoparticles can be better controlled. Researchers need to be able to strictly control the size of the nanoparticles as well as the interparticle spacing, since these parameters influence the particles’ resonance frequency and hence the way they behave in a device.

In particular, our work has shown that microplasma-assisted electrochemistry parameters could be used to control the growth of silver nanoparticles in the absence of a chemical reducing agent, both with and without a stabilizer (such as fructose) and with and without stirring. This result is important on two fronts. First, and as mentioned, the absence of a toxic reducing agent leads to a much more environmentally- and human-health friendly synthesis method while providing a good degree of control over nanoparticle size, spacing and surface chemistry. Second, since stabilizers can obscure the signal from molecules of interest in a sensing device, a stabilizer-free nanoparticle synthesis technique overcomes this problem nicely.

Full details of the research can be found in the journal Nanotechnology.

About the author
Xiao Xia Zhong is an associate professor in the Key Laboratory for Laser Plasmas (Ministry of Education) and the Department of Physics at Shanghai Jiao Tong University, People’s Republic of China. Xun Zhi Huang, Yi Lu and Yong Sheng Li are students at Shanghai Jiao Tong University, under the supervision of Xiao Xia Zhong. Amanda Rider is an OCE postdoctoral fellow at CSIRO Materials Science and Engineering and an honorary associate at the School of Physics, the University of Sydney, Australia. Scott Furman is deputy chief – science – at CSIRO Materials Science and Engineering, Australia. Kostya (Ken) Ostrikov is a CEO science leader, Australian future fellow, and chief research scientist with CSIRO Materials Science and Engineering and an honorary professor at the University of Sydney, University of Technology Sydney and the University of Wollongong, Australia.
This work was partially supported by the National Science Foundation of China (grant numbers
11275127 and 90923005), the Shanghai Science and Technology Committee (grant number 09ZR1414600), the National ITER Plans Program of China (grant number 2009GB105000), the CSIRO OCE Science Leadership Program, the CSIRO Sensors and Sensor Network Transformational Capability Program and the Australian Research Council. Amanda Rider also thanks the OCE postdoctoral fellowship scheme for financial support.