Researchers at the US Department of Energy’s Argonne National Laboratory produced completely “green” hydrogen fuel by utilizing light to initiate a catalytic process. The key was to use bacteriorhodopsin, a protein found in ancient desert microorganisms, and combine it with semiconducting titanium dioxide nano-particles.
Splitting the water molecules by exposing titanium dioxide nanoparticles to bright ultraviolet light is known as the Honda-Fujishima effect, a process that was discovered back in the 1970s. Since then, researchers have made numerous attempts to extend the light reactivity of the photocatalyst to the visible part of the electromagnetic spectrum.
In their efforts to increase the efficiency of the reaction, the scientists from Argonne National Laboratory conducted a series of experiments to establish ways in which titanium dioxide could react with the visible and not only the UV light.
This is when the team turned to the protein bacteriorhodopsin , which colors many salt flats in California and Nevada in purple. It has the ability to utilize sunlight in order to maintain the process of transferring protons from inside the cell to the extracellular space.
The team at Argonne combined the protons provided by the protein with electrons at small platinum sites within a titanium dioxide matrix. According to Peng Wang, one of the researchers involved in the study, these platinum nanoparticles were the key to the successful accomplishment of the experiment.
Thanks to the bacteriorhodopsin protein integrated in a bio-assisted hybrid, the scientists were able to produce hydrogen under white light. The new system was not only much more efficient, but it is also extremely cost-effective. The conditions at which it operates are environmentally friendly, making the production of “green” hydrogen fuel now much more feasible.