25 January 2022
A shocking success with nanoparticles
Published online 26 November 2021
An electric shock jolts cellulose and metals into improved nanoparticles.
Metal-coated nanoparticles with potential in catalysis and electrochemistry will become more effective thanks to a new fabrication process. It was developed by researchers in South Korea and the United States, with assistance from the Saudi Aramco Research and Development Center in Saudi Arabia.
In the process, a metal precursor is loaded on to a substrate of partially carbonized cellulose, placed on carbon paper. This is then exposed to a ‘carbothermal shock’, in which a brief electric current causes a sharp rise in temperature in the metallic and carbon-based compounds. This leads to the formation and high coverage of nanoparticles on the substrate surface.
Previous research using other carbon-based substrates led to the formation of fewer metal nanoparticles on the surface. Woo-Bin Jung at Harvard University, in the US, explains that their innovation achieves very high density and uniform metal nanoparticle coverage. This improvement will be vital for fully exploiting the potential in electrochemistry and catalysis that had been indicated by the previous more limited fabrication techniques. It avoids problems found when too much of the substrate remained exposed beneath the overlying metallic nanoparticles.
The key to more effective coverage appears to be the creation of chemical features called defect sites in the substrate, to which the metal components can attach. This has allowed up to 85% of the substrate surface to become coated with metal nanoparticles.
The researchers demonstrated the potential of some of their copper-based nanomaterials by using them to catalyse the chemical conversion of carbon dioxide gas into useful small organic molecules, including ethylene and ethanol. There are also possibilities for catalysing other industrially useful reactions and energy storage applications.
"We will now try to develop electrocatalysts for carbon dioxide reduction reactions that will contribute to developing a carbon-neutral society," Jung says.
Jung, W-B., et al. Generation of high-density nanoparticles in the carbothermal shock method. Sci. Adv. 7, eabk2984 (2021).