Artificial photosynthesis, as radical as it sounds, is hardly considered as new technology. There have been many iterations of the concept, but its most important end goal, among other byproducts, is the same: harness the potential to produce hydrogen and other fuels using its natural processes.
This latest research again revives the old idea, with a peculiar focus on hydrogen, and a particular feature of being the closest to actually mimicking real photosynthesis yet.
Not Just a Molecule, But a Supramolecule
Chemists from the U.S. Department of Energy’s (DOE) Brookhaven National Laboratory and Virginia Tech took inspiration from nature by developing photocatalysts, combined together to form a “supramolecule”. Made of ruthenium metal ions connected to a single catalytic center made of rhodium metal ions, hydrogen is efficiently produced through the ruthenium catalysts, via a “bridging molecule” connecting it to the ruthenium centers.
In simpler terms, the supramolecule absorbs light, separates the electrical charge produced, and catalyzes the reactions that would lead to the production of glucose. The only difference is that it stops short from combining hydrogen, and simply goes on to harvest the gas.
The researchers have developed two different systems that use the same component elements. However, they have noticed that one of the systems is considerably more efficient in producing hydrogen than the other. Upon further investigation, they have found out that the more efficient system, the one with the larger surpramolecule, is actually more electron-poor. Being electron-poor technically makes it more “hungry” for electrons, and thus promotes the reactions for photosynthesis better.
Regardless of the disparity between the developed systems, their concept of artificial photosynthesis worked. The discoveries even helped further solidify the research’s objectives, as the current investigation now focuses on finding out what makes its individual atomic components tick.
Stable Hydrogen Production, Someday
For the record, the research currently claims that the more efficient system is capable of producing 280 hydrogen molecules for every catalyst molecule for 10 hours straight. This is about seven times more efficient than the other system, which only produced 40 hydrogen molecules for 4 hours before ceasing to function completely.
Is this efficient enough for a hypothetical hydrogen production plant that uses this method? Sadly, not just yet. But the research shows promise. It successfully demonstrated that an actual photosynthetic reaction can almost be mimicked to an astonishingly close, yet controlled, degree. As for its significance to hydrogen as an alternative fuel, it means that energy expenditure, the most basic efficiency hurdle for hydrogen production, is coming closer to being solved, at least from a methodology standpoint.
That said, the efficient establishment of infrastructure and platform for the technology itself is ironically its current biggest issue. The publication also gave no hints on scaling up the technology, so it is most likely that further refinements are still required before it becomes practical enough for (potential) commercial use.
Source: Brookhaven National Laboratory