An international team of researchers has transferred certain structural properties of natural enzymes that provide a particularly high catalytic activity to metallic nanoparticles. The required chemical reaction did not lead to the surface of the particles as usual, but to the channels inside the metal particles – and to the three-fold higher catalytic activity. Teams from the University of New South Wales, Australia and Ruhr-Universität Bochum, Germany, reported on these nanosciences Bulletin of American Chemical Society, published online on September 23, 2018.
Active channels in channels
In the case of enzymes, there are active centers where a chemical reaction takes place. The reactants must pass through the channel from the surrounding solution to the active site where the spatial structure provides particularly advantageous reaction conditions. "It is assumed, for example, that the local pH value prevails in the channels and that the electronic environment in the active sites is also responsible for the effectiveness of natural enzymes," says Professor Wolfgang Schuhmann, head of the Bochum Science Center for Electrochemistry.
Channels produced in parts of nickel and platinum
To artificially mimic the enzymatic structures, the researchers produced nickel and platinum particles with a diameter of about 10 nanometers. Then they removed the nickel using chemical etching, creating channels. In the final step, the active centers deactivated on the surface of the particles. "This allowed us to ensure that only active centers in the channels were involved," explains Patrick Wilde, Ph.D. candidate at the Center for Electrochemical Sciences. Scientists compared the catalytic activity of the particles thus created with the activity of conventional particles with active centers on the surface.
Three times more activity
For the test, the team used reductive oxygen, which is also the basis for fuel cell operation. Active channels at the end of the channel catalyze the reaction three times more efficiently than the active centers on the surface of the particles.
"The results show the enormous potential of nanosymes." Corina Andronescu, Head of the Group of the Center for Electrochemical Sciences. Scientists now want to extend the concept to further reactions, such as electrocatalytic CO2 reduction and more detailed examination of the principles of increased activity. "We'd like to be able to emulate how enzymes work even better," Schuhmann adds. "Ultimately, we hope this concept will contribute to industrial applications to increase the efficiency of energy conversion processes using renewable electricity."
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